JP4911816B2 - Simple method for predicting weld metal properties and determining welding conditions - Google Patents
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- 239000002184 metal Substances 0.000 title claims description 93
- 229910052751 metal Inorganic materials 0.000 title claims description 93
- 238000000034 method Methods 0.000 title claims description 47
- 238000001816 cooling Methods 0.000 claims description 48
- 239000000463 material Substances 0.000 claims description 23
- 238000004364 calculation method Methods 0.000 claims description 19
- 239000010953 base metal Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 description 9
- 239000002994 raw material Substances 0.000 description 9
- 238000012360 testing method Methods 0.000 description 7
- 229910052748 manganese Inorganic materials 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
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Description
【０００１】
【発明の属する技術分野】
本発明は、アーク溶接、レーザー溶接、電子ビーム溶接法などによって溶接を行なう際に、溶接施工後における溶接金属の特性を溶接施工条件等によって予測すると共に、得られる溶接金属の機械的特性を予測し、あるいは更に、目標とする機械的特性の溶接金属を得ることのできる溶接施工条件を簡便に決定することのできる方法に関するものである。
【０００２】
【従来の技術】
近年、船舶、鉄骨、橋梁等の建築構造物の溶接施工に様々な溶接法が適用されている。こうした溶接施工を実施するに当たり、施工後における溶接金属の機械的特性を予め予測することは、目標特性を満たす溶接金属を得る上で重要となる。
【０００３】
溶接金属の機械的特性を予測する技術としては、例えば特許第２８５０７７３号に、サブマージアーク溶接を対象として、母材成分、溶接電流、溶接電圧、溶接速度、ワイヤ成分およびフラックス成分から溶接金属の組成を予測することで該溶接金属の特性を予測する技術が提案されている。しかし実際には、母材形状の違いやパス間温度等に起因する熱履歴によって溶接金属組織が違ってくるので、溶接金属の特性を精度よく予測することはできない。
【０００４】
一方、溶接金属の特性を溶接条件等によって精度良く予測することは、目標とする特性を得る為の最適溶接施工条件を決定する上で有用と思われるが、こうした技術は現在のところ確立されていない。なお溶接条件推定法としては、例えば特開平４−１４３０７５号に、サブマージアーク溶接を対象とし、溶込み深さと余盛量を求め、この溶込み深さと余盛量が目標許容範囲内に入る様な溶接条件（溶接電流や開先形状）を得ることを目的とした技術が提案されている。しかしこの技術は、溶接金属に求められる目標機械特性を得る為の最適な溶接施工条件を決定するものではない。
【０００５】
更に母材となる鋼板の材質予測については、圧延制御に関して多くの技術が提案されており、例えば特開平５−８７８００号公報には、金属組織を考慮した予測手法が開示されている。即ち母材金属の金属組織を基に、各金属組織（オーステナイト、フェライト、セメンタイトなど）に応じて異なった計算法を採用すると共に、母材板厚方向各位置での冷却速度も考慮して適正な金属組織を得る方法を開示している。
【０００６】
【発明が解決しようとする課題】
上記の様に溶接金属の機械的特性を予測する従来法では、母材成分、溶接電流、溶接電圧、溶接速度、ワイヤ成分およびフラックス成分から溶接金属の組成を予測することで特性を予測しているが、前述した如く実際には、母材形状の違いやパス間温度に起因する熱履歴により溶接金属の特性が異なるため、溶接金属の機械的特性を精度よく予測することができない。しかもこの種の従来技術では、母材形状による影響を所定関係式の係数で規定することにより補正しているが、前述の如く一定の係数を採用しているので、母材形状が変わると精度が低下してしまう。こうした難点を補うには、母材形状毎に多数の実験を行なってその都度適正な係数値を決定しなければならず、多大な労力が強いられる。
【０００７】
本発明はこうした状況の下でなされたものであり、その目的は、溶接施工後における溶接金属の機械的特性を、簡便にしかも精度良く予測することのできる方法を提供し、或いは更に、溶接金属の機械的特性が目標特性を満たす様に最適溶接施工条件を簡便に決定することのできる方法を提供することにある。
【０００８】
【課題を解決するための手段】
上記課題を達成することのできた本発明にかかる溶接金属の特性予測方法とは、溶接によって形成される溶接金属の特性を予測する方法であって、
特定の母材と特定のワイヤを用いて、種々の溶接条件で溶接を行ったときの冷却速度と、溶接金属の再熱部および原質部の夫々について機械的特性との関係を予め調べておくと共に、前記特定の母材と特定のワイヤを用いて種々の溶接条件で溶接を行なったときの再熱部と原質部の断面の面積比を予め調べておき、
前記特定の母材と特定のワイヤを用いて溶接を行う際の板厚、入熱量、パス間温度から計算によって求められる冷却速度と機械的特性の関係、および溶接条件と前記再熱部と原質部の面積比との関係を照合することにより、溶接金属の機械的特性を予測するところに要旨を有している。
【０００９】
なお本発明において溶接金属の再熱部とは、多パス溶接において、一旦溶融凝固により形成された溶接金属が、それ以後のパスによって溶融されないが溶接熱によってオーステナイト生成温度域以上に加熱された部分をいい、その他の部分を原質部という。
【００１０】
そして、本発明に係る上記溶接金属の特性予測法は、溶接時の各パスにおける入熱量が一定である溶接法に好適に適用され、また溶接法としては特にアーク溶接法に適用することによって高精度の予測を行なうことができるので好ましい。
【００１１】
また本発明に係る溶接施工条件の決定法とは、上記方法によって予測される溶接金属の特性が所望の特性を満足しているかどうかを判断し、該所望の特性を満足していない場合には、予め設定された溶接施工条件パラメーターの変更手順に従って溶接施工条件を変更し、該変更された溶接施工条件を用いて、再度溶接金属の特性を予測し、予測される溶接金属の特性が前記所望の特性を満足するまで繰り返し演算を行うことにより、所望の溶接金属特性を満足する溶接施工条件を決定するところに要旨を有している。
【００１２】
【発明の実施の形態】
溶接においては、前述した様に溶接金属部が複雑な熱履歴を受けるので、従来技術の様に溶接金属の組成を考慮しただけでは溶接金属の特性を精度良く予測することができない。なぜなら、たとえ組成が同じであったとしても、その熱履歴により原質部や再熱部の組織に顕著な違いが生じるからである。
【００１３】
即ち原質部と再熱部の金属組成が同じであっても、組織の違いにより夫々の機械的特性（特に靭性値）には著しい差が生じているため、溶接金属の機械的特性を精度よく予測するには、それぞれの面積分率を考慮する必要がある。
【００１４】
そこで本発明では、溶接金属が受ける温度履歴、特に溶接金属の冷却速度と、溶接条件による原質部と再熱部の面積分率を予測することで、溶接金属の機械的特性を従来法よりも簡便に予測可能にしたもので、これは、原質部と再熱部とで機械的特性に大きな違いがある、との知見に基づいている。即ち本発明では、特定の母材と特定の溶接ワイヤを用いて溶接を行なう場合、溶接金属の冷却速度と溶接金属（再熱部および原質部）の機械的特性との間に相関性が認められること、しかも同冷却条件における溶接金属中の原質部と再熱部の割合が溶接金属の機械的特性との間にも相関性が認められるとの知見を利用するものである。
【００１５】
従って本発明によれば、溶接金属の細かい組成や熱履歴を考慮することなく、特定の母材と溶接ワイヤを用いて溶接を行なうときの冷却速度と機械的特性の関係、および溶接条件と溶接金属中の原質部と再熱部の面積比との関係をデータベース化しておき、同じ母材と溶接ワイヤを用いた場合の冷却条件を確認するだけで、溶接金属組成や煩雑で長時間を要する熱履歴の計算を要することなく、溶接金属の機械的特性をほぼ正確に予測することに成功したものである。そして上記原質部と再熱部の面積分率は、板厚、入熱量、パス間温度で整理でき、また原質部と再熱部の機械的特性は溶接時の冷却速度によって整理できるのである。
【００１６】
以下、本発明の方法を図面に基づいて詳細に説明する。図１は、本発明方法を実施する際の手順を示すフローチャートであり、アーク溶接を実施する場合を想定している。
【００１７】
本発明を実施するに当たっては、入力データとして母材板厚と入熱量およびパス間温度を採用する。アーク溶接の場合、入熱量Ｑは「Ｑ＝ＩＥ／Ｖ」で表すことができるので、入熱量に代えて溶接電流と溶接電圧を採用しても構わない。
【００１８】
また冷却速度計算には、下記式(1)の経験式を採用する。
【００１９】
【数１】
【００２０】
ここで予測される冷却速度は最終パスでの冷却速度であり、Ｑは入熱量、θ0はパス間温度、ｈは母材板厚である。他の定数については、下記表１に示す値（「溶接工学」佐藤邦彦 理工学社 １９７９、第４１頁）を採用した。
【００２１】
【表１】
【００２２】
上記式(1)は、アーク溶接時の冷却速度計算式である。溶接を１パスで行なう場合は、式(1)をそのまま使用すればよく、多層盛溶接（多パス溶接）の場合は、各パス毎に異なる入熱量とパス間温度から冷却速度を計算すればよい。ただし、通常の多層盛溶接では、全てのパスで同一の入熱量とするのが一般的であり、またパス間温度としては、予め決められた上限パス間温度に冷却されるまで待ってから次パス溶接を行なうのが一般的であるため、この上限パス間温度を代表値として使用し、各パスの入熱量が同じ場合は、全てのパスで同一の冷却速度を用いることも可能である。
【００２３】
また、上記式(1)以外の経験式から冷却速度を予測しても構わない。更には、例えば下記式(2)で示される様な３次元熱伝導方程式を用いて、各パスでの冷却速度を予測することも可能である。
【００２４】
【数２】
【００２５】
上記式(2)において、Ｈはエンタルピー、Ｋは熱伝導度、ｑは単位体積当たりの溶接トーチからの入熱、Ｔは温度、ｖは溶接速度、ρmは密度を表している。そしてこの様な式を用いた計算を行なうことで、より精緻にパス前温度と冷却速度を知ることができる。他の溶接法を採用するときは他の経験式を使用すればよい。
【００２６】
そして、上記式(1)または(2)で求められる冷却速度と、予め調べておいた溶接金属再熱部の機械的特性とを照合し、再熱部の機械的特性を求める。図示するフローチャート例では、機械的特性として強度と靭性値を採用しており、これら各機械的特性計算の順序は任意である。また、硬さなど他の特性のデータベースを用意しておけば、他の特性を予測することも可能である。
【００２７】
次に、式(1)または(2)で求められた冷却速度と、予め調べておいた溶接金属原質部の機械的特性とを照合し、原質部の機械的特性を求める。図示例では同様に機械的特性として強度と靭性値を求めているが、これら各機械的特性計算の順序も任意であり、また、硬さなど他の特性のデータベースを用意しておけば、他の特性を予測し得ることも上記と同じである。
【００２８】
また上記図１のフローチャートでは、再熱部→原質部の順序で計算を行なう例を示したが、この順序も任意であり、原質部→再熱部の順で計算しても勿論構わない。
【００２９】
次に、予め調べておいた母材板厚、入熱量、パス間温度と、施工される溶接金属の原質部と再熱部の面積割合によって、所望する溶接金属部分の機械的特性を計算する。本例では所望する部分として、板厚２／３の位置、半径６ｍｍの引張試験片採取位置と、板厚２／３の位置、高さ１０ｍｍのシャルピー衝撃試験片採取位置の２種類を用いた。その他の形状の試験片を用いる場合には、試験片採取位置に即した面積割合のデータベースを準備しておけばよい。また、溶接部の断面写真をデータベースとして採取しておき、該断面写真から所望位置での原質部と再熱部の面積割合を知る方法もある。
【００３０】
そして最後に、所望する位置の強度・靭性を前記原質部と再熱部の面積割合で配分すれば、例えば後記実施例で詳述する如く、当該位置での溶接金属の強度や靭性を精度よく予測することができる。
【００３１】
上記の様に本発明の特性予測法を採用すれば、予測される溶接金属の機械的特性が目標特性を満たしているかどうかを判断することができる。そして、予測される機械的特性が目標特性を満たしていない場合は、予め設定されている溶接施工条件（入熱量やパス間温度など）を変更して再度溶接金属の機械的特性を予測し、予測される特性が前記目標とする溶接金属特性を満足するまで繰り返し演算を行なうことにより、目標の溶接金属特性を満たす溶接施工条件を決定することができる。
【００３２】
【実施例】
以下、実施例によって本発明をより具体的に説明するが、下記実施例は本発明を限定する性質のものではなく、前・後記の趣旨に適合し得る範囲で適宜変更を加えて実施することも可能であり、それらは何れも本発明の技術的範囲に含まれる。
【００３３】
比較例（従来法）
従来の予測手法では、母材形状を考慮していないため、母材形状が変わると熱履歴が変わり予測精度が低下する。たとえ母材形状を考慮したとしても、パス間温度等の施工条件が変われば特性が変化し、溶接金属の特性を精度良く予測することはできない。
【００３４】
以下に、パス間温度以外の条件をすべて同一とし、パス間温度のみを変化させてガスシールドアーク溶接法により溶接金属を作製し、その強度（ＴＳ）と靱性（０℃でのＶシャルピー衝撃値：ｖＥ0）を評価した。このときの溶接条件は下記の通りとした。
（溶接条件）
鋼板：ＳＭ４９０ ２０ｍｍt×１７５ｍｍw×３００ｍｍL
関先：レ型３５°
シールドガス：ＣＯ2 １００％、２５リットル／ｍｉｎ．
電流−電圧−溶接速度：３４０Ａ−３２Ｖ−２５ｃｐｍ
入熱：２５ｋＪ／ｃｍ
溶接ワイヤ：ＪＩＳ Ｚ３３１２（ＹＧＷ１１）（C:0.07%、Si:0.80%、Mn:
1.5%、Ti:0.20%、P＜0.03%、S＜0.03%)
ワイヤ径：１．４ｍｍφ
パス間温度：３５０℃または４５０℃
【００３５】
その結果、パス間温度が３５０℃のときは、ＴＳ＝５４０ＭＰａ，ｖＥ0＝１３６Ｊ、パス間温度が４５０℃のときは、ＴＳ＝４９８ＭＰａ，ｖＥ0：２４Ｊであり、パス間温度が３５０℃から４５０℃に変化しただけでも、衝撃吸収エネルギーで示される靭性値は、約１／６に低下することが分かる。
【００３６】
また、溶接金属の化学組成を分析した結果は下記表２に示す通りであり、Ｃ，Ｓｉ，Ｍｎ，Ｐ，Ｓ，Ｔｉ，Ｏ，Ｎにおいて有意な差は認められず、組成データを採用するだけでは特性予測を精度良く行なうことはできなかった。
【００３７】
【表２】
【００３８】
実施例１（本発明法）
そこで、下記の溶接条件でガスシールドアーク溶接を行い、前記図１に示すフローチャートに従って特性予測を行なったときの、実測した溶接金属の特性を比較した。
（溶接条件）
母材形状：２０ｍｍt×１７５ｍｍw×４００ｍｍL
開先形状：レ型３５°
母材成分：ＳＭ４９０（C:0.13%、Si:0.30%、Mn:1.2%）
ワイヤ成分：ＪＩＳ Ｚ３３１２（ＹＧＷ１１）（C:0.07%、Si:0.80%、Mn:
1.5%、Ti:0.20%、P＜0.03%、S＜0.03%）
初期温度：２５℃
溶接速度：２８ｃｐｍ
溶接電流：３６０Ａ
溶接電圧：３９Ｖ
パス間温度：３５０℃
シールドガス：ＣＯ2 １００％，２５リットル／ｍｉｎ．
ワイヤ径：１．４ｍｍ
【００３９】
本実施例では、最初に、冷却速度と原質部の機械的特性との関係を予め調べるため、下記の条件でシングルビード試験片を作製し、靭性試験を行った。この際、板厚および初期母材温度を変化させることで、８００℃から５００℃までの間の冷却速度を表３に示す如く変化させた。ここで準備するデータの数が多いほど、後の特性予測精度は向上するので、できるだけ多くのデータを採取しておくことが望ましい。各冷却速度における靭性値（シャルピー衝撃値）を表３に示す。
開先形状：Ｖ型４５度
母材成分：ＳＭ４９０（C:0.13%、Si:0.30%、Mn:1.2%）
ワイヤ成分：ＪＩＳ Ｚ３３１２（ＹＧＷ１１）（C:0.07%、Si:0.80%、Mn:
1.5%、Ti:0.20%、P＜0.03%、S＜0.03%）
シールドガス：ＣＯ2 １００％、２５リットル／ｍｉｎ
ワイヤ径：１．４ｍｍ
【００４０】
【表３】
【００４１】
次に、冷却速度と再熱部の機械的特性との関係を予め調べるため、原質部と同様のシングルビード試験を採用して熱サイクル試験を行い、靭性試験を行った。冷却速度は、冷却時のガス流量を調整することで表４に示す如く変化させた。冷却速度範囲は同様に８００℃から５００℃までとした。ここで準備するデータの数も多いほど、後の特性予測精度が向上するので、できるだけ多くのデータを採取しておくのが望ましい。冷却速度と靭性値（シャルピー衝撃値）の関係を表４に示す。
【００４２】
【表４】
【００４３】
次に、種々の溶接条件で溶接を行ったときの、再熱部と原質部の断面の面積比を調べた。溶接条件は、下記表５に示す６条件とした。面積比率は、板底から２／３位置、高さ１０ｍｍのシャルピー衝撃試験片採取位置での値である。ただし板厚１２ｍｍのものについては、板厚中心位置での面積割合とした。面積比は、ミクロエッチングした断面写真から測定した。ここで準備するデータの数も多いほど、後の特性予測精度が向上するため、できるだけ多くのデータを採取しておくのが望ましい。この時の原質部および再熱部の面積割合を表５に示す。
【００４４】
【表５】
【００４５】
ここまでの準備をしておき、下記表６に示す８条件で予測値と実測値を比較したところ、本発明の予測法が高精度の予測方法であることを確認した。すなわち最初に、板厚、入熱量、パス間温度から計算によって最終パスの冷却速度を予測した。予測のための冷却速度計算には前記式(1)を用いた。予測結果は下記表６に示す通りであった。
【００４６】
【表６】
【００４７】
次に、上記計算で予測した冷却速度と、再熱部および原質部の機械的特性を照合した。この場合、例えば溶接条件２（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：350℃）を例にとると、予測される冷却速度は４℃／secであるが、表３に示す原質部の靭性データベースには４℃/secが存在しない。この様な場合は、８℃/sec＝６１Jと３℃/sec＝３４Jを一次補間し、４℃／secの原質部靭性値を３９Jと予測する。再熱部についても同様に、表４に示した５℃/sec＝１９０Jと１℃/sec＝２０７Jを一次補間し、４℃／secの再熱部靭性値を１９４Jと予測する。
【００４８】
最後に、再熱部と原質部の面積比によって、再熱部と原質部の機械的特性を加重平均し、所望の部位における機械的特性を予測する。たとえば溶接条件２を例にとると、原質部と再熱部の面積比率は５０％：５０％であるので
３９J×50/100＋１９４Ｊ×50/100＝１１７Ｊ
から、溶接条件２の靭性値は１１７Ｊであると予測される。
【００４９】
また、溶接条件と原質部／再熱部面積比について照合する溶接条件が存在しない場合は、次の様にして面積比の予測を行なう。例えば原質部と再熱部の面積比を知るデータベースは、前記表５に示す如く６条件のみであり、表６の溶接条件７（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：300℃）と同一の溶接条件が存在しない。この様な場合は、溶接条件２（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：350℃）の面積比［５０％：５０％］と溶接条件６（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：250℃）の面積比［５５％：４５％］のデータを一次補間し、溶接条件７（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：300℃）の面積比率を５２．５％：４７．５％と予測する。
【００５０】
計算に要した時間は、各溶接条件につき、パーソナルコンピュータで約１秒である。この予測結果と、上記溶接条件で溶接金属を作製し靭性試験を行なった実測結果は表７に示す通りであり、最大誤差１３％で靭性値を予測できることが確認された。
【００５１】
【表７】
【００５２】
実施例２（溶接パス毎の冷却速度計算により予測精度を高めた例）
前記実施例１と同様にして、各冷却速度における原質部の靭性値（表３）と再熱部の靭性値（表４）を予め求め、更に種々の溶接条件で溶接を行なった時の再熱部と原質部の面積割合（表５）を求めておく。
【００５３】
そして、表５の溶接条件２（入熱：30,000J/cm、板厚：２０ｍｍt、パス間温度：350℃）で得た溶接部の断面写真から、最終パスと最終前パスの２パスにおける再熱部と原質部の面積比率を求めた。結果は表８に示す通りであった。
【００５４】
【表８】
【００５５】
次に前記式(2)を解くことで、各パスの冷却速度をそれぞれ予測した。なお熱伝導度および密度は、母材成分およびワイヤ成分から予め用意しておいたデータベースを用いて決定した。
【００５６】
そして、溶接金属部と母材部をメッシュ分割して計算を行なったところ
最終パスの冷却速度：４．１℃/sec
最終前パスの冷却速度：４．３℃/sec
を得た。なお、溶接金属部のメッシュサイズは２ｍｍ、母材部のメッシュサイズは溶接金属部からの距離に比例して大きくし、メッシュ分割法は直交格子系とした。
【００５７】
尚、メッシュサイズを変化させることで冷却速度予測の精度と計算に要する時間を変えることができ、メッシュサイズを細かくするほど精度は向上するが、計算に要する時間は長くなる。十分な予測精度を確保するには、メッシュサイズを溶接金属の幅方向・高さ方向に少なくともパス数以上に分割することが望ましい。しかし一方で、予測精度は、メッシュサイズが板厚／(パス数×３０)程度でほぼ飽和し、それ以上に細かなメッシュ分割をしても、いたずらに予測所要時間が延長するだけであるので、それ以上の再分割は無意味である。
【００５８】
次に、上記計算で予測した冷却速度と、再熱部および原質部の機械的特性を照合した。その際、冷却速度が照合するデータベースに存在しない場合は、前記実施例１で説明したのと同様にして一次の補間により機械的特性を予測した。結果を表９に示す。
【００５９】
【表９】
【００６０】
最後に、再熱部と原質部の面積比によって、再熱部と原質部の機械的特性を過重平均し、所望部位での機械的特性を予測したところ、予測結果は１１８．４Ｊで、予測誤差は５．３％であった。この予測誤差は、前記実施例１における溶接条件２での予測誤差：７％に比べて更に小さくなっており、このことから、複数パス溶接においては、各パスにおける冷却速度から予測することで精度を更に高め得ることが分かる。
【００６１】
従って本発明によれば、用途や目的に応じた溶接金属の目標機械的特性が決められている場合は、上記の様な方法で機械的特性を予測し、予測される該機械的特性が目標特性を満たしていない場合は、予め設定されている溶接施工条件（入熱量やパス間温度など）を変更して再度溶接金属の機械的特性を予測し、予測される特性が前記目標とする溶接金属特性を満足するまで繰り返し演算を行なうことにより、目標の溶接金属特性を満たす溶接施工条件を決定することができる。
【００６２】
【発明の効果】
本発明は以上の様に構成されており、溶接施工後における溶接金属の機械的特性を簡便にしかも精度良く予測することができ、あるいは更に、簡便な手段で溶接金属の機械的特性が目標特性を満たす様な最適溶接施工条件を決定し得ることになった。
【図面の簡単な説明】
【図１】本発明方法を実施する際の手順を示すフローチャート例である。[0001]
BACKGROUND OF THE INVENTION
The present invention predicts the characteristics of the weld metal after welding by welding conditions, etc., and also predicts the mechanical characteristics of the resulting weld metal when performing welding by arc welding, laser welding, electron beam welding, etc. In addition, the present invention relates to a method capable of easily determining welding conditions for obtaining a weld metal having a target mechanical characteristic.
[0002]
[Prior art]
In recent years, various welding methods have been applied to welding construction of building structures such as ships, steel frames and bridges. In carrying out such welding, it is important to predict in advance the mechanical properties of the weld metal after the construction in order to obtain a weld metal that satisfies the target properties.
[0003]
As a technique for predicting the mechanical properties of the weld metal, for example, Japanese Patent No. 2850773, for submerged arc welding, the composition of the weld metal from the base material component, welding current, welding voltage, welding speed, wire component and flux component is used. A technique for predicting the characteristics of the weld metal by predicting the above has been proposed. However, in practice, the weld metal structure differs depending on the thermal history caused by the difference in the shape of the base metal, the temperature between passes, and the like, so the characteristics of the weld metal cannot be accurately predicted.
[0004]
On the other hand, accurate prediction of weld metal characteristics based on welding conditions, etc., may be useful in determining the optimum welding conditions for obtaining the target characteristics, but such technology has been established at present. Absent. As a welding condition estimation method, for example, in Japanese Patent Laid-Open No. 4-143075, submerged arc welding is targeted, the penetration depth and the amount of surplus are obtained, and welding conditions such that the penetration depth and the amount of surplus are within the target allowable range ( Techniques aimed at obtaining welding current and groove shape) have been proposed. However, this technique does not determine optimum welding conditions for obtaining the target mechanical characteristics required for the weld metal.
[0005]
Furthermore, regarding the prediction of the material quality of a steel plate as a base material, many techniques have been proposed regarding rolling control. For example, Japanese Patent Laid-Open No. 5-87800 discloses a prediction method considering a metal structure. In other words, based on the metal structure of the base metal, a different calculation method is adopted for each metal structure (austenite, ferrite, cementite, etc.), and the cooling rate at each position in the thickness direction of the base metal plate is taken into account. A method for obtaining a stable metal structure is disclosed.
[0006]
[Problems to be solved by the invention]
In the conventional method for predicting the mechanical properties of the weld metal as described above, the properties are predicted by predicting the composition of the weld metal from the base material component, welding current, welding voltage, welding speed, wire component and flux component. However, as described above, since the characteristics of the weld metal differ in practice due to the difference in the shape of the base material and the thermal history due to the interpass temperature, the mechanical characteristics of the weld metal cannot be accurately predicted. Moreover, in this type of prior art, the influence of the base material shape is corrected by specifying the coefficient of the predetermined relational expression. However, since a constant coefficient is adopted as described above, the accuracy changes if the base material shape changes. Will fall. In order to make up for these difficulties, a large number of experiments must be performed for each base material shape to determine an appropriate coefficient value each time, and a great deal of labor is required.
[0007]
The present invention has been made under such circumstances, and an object of the present invention is to provide a method capable of easily and accurately predicting the mechanical properties of a weld metal after welding, or further, weld metal. It is an object of the present invention to provide a method by which the optimum welding conditions can be easily determined so that the mechanical characteristics of the steel satisfy the target characteristics.
[0008]
[Means for Solving the Problems]
The method for predicting the properties of a weld metal according to the present invention, which has been able to achieve the above-mentioned problems, is a method for predicting the properties of a weld metal formed by welding,
Preliminarily investigate the relationship between the cooling rate when welding is performed under various welding conditions using a specific base material and a specific wire, and the mechanical properties of the reheated part and the original part of the weld metal. In addition, the area ratio of the cross-section of the reheated part and the raw part when the welding is performed under various welding conditions using the specific base material and the specific wire,
Relationship between the plate thickness, heat input, cooling rate obtained by calculation from the interpass temperature and mechanical characteristics when welding using the specific base material and the specific wire, and welding conditions, the reheated portion and the original The gist is that the mechanical properties of the weld metal are predicted by collating the relationship with the area ratio of the mass part.
[0009]
In the present invention, the reheated portion of the weld metal is a portion in which welding metal once formed by melt solidification in multi-pass welding is not melted by subsequent passes but is heated to austenite generation temperature range or higher by welding heat. The other part is called the original part.
[0010]
The method for predicting the characteristics of the weld metal according to the present invention is preferably applied to a welding method in which the heat input amount in each pass during welding is constant, and the welding method is particularly high by being applied to an arc welding method. This is preferable because accuracy can be predicted.
[0011]
The method for determining welding conditions according to the present invention is to determine whether or not the characteristics of the weld metal predicted by the above method satisfy the desired characteristics, and when the desired characteristics are not satisfied. The welding conditions are changed in accordance with a preset welding condition parameter changing procedure, and the characteristics of the weld metal are predicted again using the changed welding conditions. The present invention has a gist in that a welding operation condition that satisfies desired weld metal characteristics is determined by repeatedly performing calculation until the above characteristics are satisfied.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In welding, since the weld metal part receives a complicated heat history as described above, the characteristics of the weld metal cannot be accurately predicted only by considering the composition of the weld metal as in the prior art. This is because even if the composition is the same, the thermal history causes a significant difference in the structure of the primary part and the reheated part.
[0013]
In other words, even if the metal composition of the original part and the reheated part are the same, there is a significant difference in the mechanical properties (particularly the toughness value) due to the difference in structure, so the mechanical properties of the weld metal are accurate. In order to predict well, it is necessary to consider each area fraction.
[0014]
Therefore, in the present invention, the mechanical properties of the weld metal are compared with the conventional method by predicting the temperature history of the weld metal, particularly the cooling rate of the weld metal, and the area fraction of the original part and the reheated part depending on the welding conditions. This is based on the knowledge that there is a great difference in mechanical properties between the primary part and the reheat part. In other words, in the present invention, when welding is performed using a specific base material and a specific welding wire, there is a correlation between the cooling rate of the weld metal and the mechanical properties of the weld metal (reheated part and original part). In addition, the fact that there is a correlation between the ratio of the original part and the reheated part in the weld metal under the same cooling condition is also used with the mechanical properties of the weld metal.
[0015]
Therefore, according to the present invention, the relationship between the cooling rate and the mechanical characteristics when welding is performed using a specific base material and a welding wire, and the welding conditions and welding are considered without considering the fine composition and thermal history of the weld metal. By creating a database of the relationship between the area ratio of the primary part and reheated part in the metal, and confirming the cooling conditions when using the same base material and welding wire, the weld metal composition and the complicated and long time can be saved. The present inventors succeeded in predicting the mechanical properties of the weld metal almost accurately without calculating the required heat history. And the area fraction of the above-mentioned original part and reheat part can be arranged by the plate thickness, heat input and interpass temperature, and the mechanical properties of the original part and reheat part can be arranged by the cooling rate during welding. is there.
[0016]
Hereinafter, the method of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing a procedure for carrying out the method of the present invention, and assumes a case where arc welding is carried out.
[0017]
In practicing the present invention, the base plate thickness, the heat input amount, and the interpass temperature are adopted as input data. In the case of arc welding, the heat input Q can be expressed by “Q = IE / V”, so that a welding current and a welding voltage may be employed instead of the heat input.
[0018]
The empirical formula (1) below is used for the cooling rate calculation.
[0019]
[Expression 1]
[0020]
The cooling rate predicted here is the cooling rate in the final pass, Q is the amount of heat input, θ 0 is the interpass temperature, and h is the base metal plate thickness. For the other constants, the values shown in Table 1 below (“Welding Engineering” Kunihiko Sato, Science and Engineering 1979, page 41) were adopted.
[0021]
[Table 1]
[0022]
The above formula (1) is a formula for calculating the cooling rate during arc welding. When welding is performed in one pass, equation (1) can be used as it is. In multi-layer welding (multi-pass welding), the cooling rate can be calculated from the amount of heat input and the temperature between passes that differ for each pass. Good. However, in normal multi-layer welding, the same heat input is generally used in all passes, and the interpass temperature is waited until it is cooled to a predetermined upper limit pass temperature before the next. Since pass welding is generally performed, this upper limit pass temperature is used as a representative value, and if the heat input amount of each pass is the same, the same cooling rate can be used for all passes.
[0023]
Further, the cooling rate may be predicted from an empirical formula other than the above formula (1). Furthermore, it is also possible to predict the cooling rate in each pass by using, for example, a three-dimensional heat conduction equation represented by the following formula (2).
[0024]
[Expression 2]
[0025]
In the above formula (2), H represents enthalpy, K represents thermal conductivity, q represents heat input from the welding torch per unit volume, T represents temperature, v represents welding speed, and ρ m represents density. Then, by performing calculation using such an expression, it is possible to know the temperature before cooling and the cooling rate more precisely. Other empirical formulas may be used when other welding methods are employed.
[0026]
Then, the cooling rate obtained by the above formula (1) or (2) is collated with the mechanical properties of the weld metal reheated portion investigated in advance to obtain the mechanical properties of the reheated portion. In the illustrated flowchart, strength and toughness values are adopted as mechanical characteristics, and the order of calculating these mechanical characteristics is arbitrary. In addition, if a database of other characteristics such as hardness is prepared, other characteristics can be predicted.
[0027]
Next, the cooling rate obtained by the equation (1) or (2) is collated with the mechanical properties of the weld metal raw material portion examined in advance to obtain the mechanical properties of the raw material portion. In the example shown in the figure, the strength and toughness values are similarly obtained as the mechanical properties. However, the order of calculation of these mechanical properties is arbitrary, and if other properties such as hardness are prepared, other It is the same as described above that the characteristics of can be predicted.
[0028]
In the flowchart of FIG. 1, an example is shown in which the calculation is performed in the order of the reheat part → the raw material part. However, this order is also arbitrary, and of course, the calculation may be performed in the order of the raw material part → the reheat part. Absent.
[0029]
Next, calculate the mechanical properties of the desired weld metal part based on the base metal plate thickness, heat input, interpass temperature, and the area ratio of the weld metal original part and reheat part to be constructed. To do. In this example, as the desired portion, two kinds of positions, ie, a position with a thickness of 2/3, a tensile test piece sampling position with a radius of 6 mm, and a position with a thickness of 2/3, and a Charpy impact test piece with a height of 10 mm were used. . When using test pieces of other shapes, it is only necessary to prepare a database of area ratios according to the test piece collection positions. In addition, there is a method in which a cross-sectional photograph of a welded portion is collected as a database, and the area ratio between the original portion and the reheated portion at a desired position is obtained from the cross-sectional photograph.
[0030]
And finally, if the strength and toughness at the desired position are distributed by the area ratio of the original part and the reheated part, the strength and toughness of the weld metal at that position can be accurately determined, for example, as described in detail in Examples below. Can be predicted well.
[0031]
If the characteristic prediction method of the present invention is employed as described above, it can be determined whether or not the predicted mechanical characteristics of the weld metal satisfy the target characteristics. And when the predicted mechanical properties do not meet the target properties, the welding conditions (such as heat input and interpass temperature) set in advance are changed and the mechanical properties of the weld metal are predicted again, By repeatedly performing the calculation until the predicted characteristics satisfy the target weld metal characteristics, it is possible to determine welding conditions that satisfy the target weld metal characteristics.
[0032]
【Example】
Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are not of a nature that limits the present invention, and should be implemented with appropriate modifications within a range that can meet the purpose described above and below. These are all included in the technical scope of the present invention.
[0033]
Comparative example (conventional method)
In the conventional prediction method, since the base material shape is not taken into consideration, when the base material shape changes, the heat history changes and the prediction accuracy decreases. Even if the shape of the base metal is taken into account, the characteristics change if the construction conditions such as the temperature between passes change, and the characteristics of the weld metal cannot be accurately predicted.
[0034]
Below, all the conditions other than the interpass temperature are the same, and only the interpass temperature is changed to produce a weld metal by gas shielded arc welding, and its strength (TS) and toughness (V Charpy impact value at 0 ° C) : VE 0 ) was evaluated. The welding conditions at this time were as follows.
(Welding conditions)
Steel plate: SM490 20mm t x 175mm w x 300mm L
Seki no: 35 °
Shielding gas: CO 2 100%, 25 liters / min.
Current-voltage-welding speed: 340A-32V-25cpm
Heat input: 25kJ / cm
Welding wire: JIS Z3312 (YGW11) (C: 0.07%, Si: 0.80%, Mn:
(1.5%, Ti: 0.20%, P <0.03%, S <0.03%)
Wire diameter: 1.4mmφ
Interpass temperature: 350 ° C or 450 ° C
[0035]
As a result, when the interpass temperature is 350 ° C., TS = 540 MPa, vE 0 = 136 J, and when the interpass temperature is 450 ° C., TS = 498 MPa, vE 0 : 24 J, and the interpass temperature is 350 ° C. It can be seen that the toughness value indicated by the impact absorption energy is reduced to about 1/6 even if the temperature is only changed to 450 ° C.
[0036]
Moreover, the result of analyzing the chemical composition of the weld metal is as shown in Table 2 below, and no significant difference is observed in C, Si, Mn, P, S, Ti, O, and N, and the composition data is adopted. It was not possible to predict the characteristics with high accuracy.
[0037]
[Table 2]
[0038]
Example 1 (method of the present invention)
Therefore, gas shield arc welding was performed under the following welding conditions, and the characteristics of the measured weld metal when the characteristics were predicted according to the flowchart shown in FIG. 1 were compared.
(Welding conditions)
Base material shape: 20mm t x 175mm w x 400mm L
Groove shape: 35 °
Base material component: SM490 (C: 0.13%, Si: 0.30%, Mn: 1.2%)
Wire component: JIS Z3312 (YGW11) (C: 0.07%, Si: 0.80%, Mn:
1.5%, Ti: 0.20%, P <0.03%, S <0.03%)
Initial temperature: 25 ° C
Welding speed: 28cpm
Welding current: 360A
Welding voltage: 39V
Interpass temperature: 350 ° C
Shield gas: CO 2 100%, 25 liters / min.
Wire diameter: 1.4mm
[0039]
In this example, first, in order to examine in advance the relationship between the cooling rate and the mechanical properties of the raw material portion, a single bead specimen was produced under the following conditions and a toughness test was performed. At this time, the cooling rate between 800 ° C. and 500 ° C. was changed as shown in Table 3 by changing the plate thickness and the initial base material temperature. Since the later characteristic prediction accuracy improves as the number of data prepared here increases, it is desirable to collect as much data as possible. Table 3 shows the toughness value (Charpy impact value) at each cooling rate.
Groove shape: V-type 45 degree Base material component: SM490 (C: 0.13%, Si: 0.30%, Mn: 1.2%)
Wire component: JIS Z3312 (YGW11) (C: 0.07%, Si: 0.80%, Mn:
1.5%, Ti: 0.20%, P <0.03%, S <0.03%)
Shielding gas: CO 2 100%, 25 liters / min
Wire diameter: 1.4mm
[0040]
[Table 3]
[0041]
Next, in order to investigate the relationship between the cooling rate and the mechanical properties of the reheated part in advance, a single bead test similar to that for the original part was adopted, a thermal cycle test was conducted, and a toughness test was conducted. The cooling rate was changed as shown in Table 4 by adjusting the gas flow rate during cooling. Similarly, the cooling rate range was 800 ° C. to 500 ° C. As the number of data prepared here increases, the later characteristic prediction accuracy improves. Therefore, it is desirable to collect as much data as possible. Table 4 shows the relationship between the cooling rate and the toughness value (Charpy impact value).
[0042]
[Table 4]
[0043]
Next, the area ratio of the cross sections of the reheated part and the original part when the welding was performed under various welding conditions was examined. The welding conditions were six conditions shown in Table 5 below. The area ratio is a value at a position where a Charpy impact test piece is collected at a position 2/3 from the plate bottom and a height of 10 mm. However, for the plate thickness of 12 mm, the area ratio at the plate thickness center position was used. The area ratio was measured from a micro-etched cross-sectional photograph. As the number of data prepared here increases, the later characteristic prediction accuracy improves, so it is desirable to collect as much data as possible. Table 5 shows the area ratios of the original part and the reheated part at this time.
[0044]
[Table 5]
[0045]
The preparation up to this point was made, and when the predicted value and the actually measured value were compared under the eight conditions shown in Table 6 below, it was confirmed that the prediction method of the present invention was a highly accurate prediction method. That is, first, the cooling rate of the final pass was predicted by calculation from the plate thickness, heat input, and interpass temperature. The above formula (1) was used for calculation of the cooling rate for prediction. The prediction results were as shown in Table 6 below.
[0046]
[Table 6]
[0047]
Next, the cooling rate predicted by the above calculation was compared with the mechanical properties of the reheat part and the raw material part. In this case, for example, when the welding condition 2 (heat input: 30,000 J / cm, plate thickness: 20 mm t , interpass temperature: 350 ° C.) is taken as an example, the predicted cooling rate is 4 ° C./sec. In the toughness database of the original part shown in 3, there is no 4 ° C./sec. In such a case, 8 ° C./sec=61 J and 3 ° C./sec=34 J are linearly interpolated, and the raw material toughness value at 4 ° C./sec is predicted to be 39 J. Similarly, for the reheated portion, 5 ° C / sec = 190 J and 1 ° C / sec = 207 J shown in Table 4 are linearly interpolated, and the reheated portion toughness value at 4 ° C / sec is predicted to be 194 J.
[0048]
Finally, the mechanical characteristics of the reheated part and the original part are weighted averaged according to the area ratio of the reheated part and the original part, and the mechanical characteristics at a desired site are predicted. For example, taking welding condition 2 as an example, the area ratio of the original part and the reheated part is 50%: 50%, so 39J × 50/100 + 194J × 50/100 = 117J.
Therefore, the toughness value of welding condition 2 is predicted to be 117J.
[0049]
In addition, when there is no welding condition for checking the welding condition and the original part / reheated part area ratio, the area ratio is predicted as follows. For example, the database for knowing the area ratio of the original part and the reheat part has only six conditions as shown in Table 5 above, and welding conditions 7 in Table 6 (heat input: 30,000 J / cm, plate thickness: 20 mm t , pass The same welding conditions as for the inter-temperature: 300 ° C) do not exist. In such a case, the area ratio [50%: 50%] of welding condition 2 (heat input: 30,000 J / cm, plate thickness: 20 mm t , interpass temperature: 350 ° C.) and welding condition 6 (heat input: 30,000 Data of area ratio [55%: 45%] of J / cm, plate thickness: 20mm t , interpass temperature: 250 ° C is linearly interpolated and welding condition 7 (heat input: 30,000J / cm, plate thickness: 20mm) t , the temperature between passes: 300 ° C.) is predicted to be 52.5%: 47.5%.
[0050]
The time required for the calculation is about 1 second with a personal computer for each welding condition. The prediction results and the actual measurement results of producing a weld metal under the above welding conditions and conducting a toughness test are as shown in Table 7, and it was confirmed that the toughness value can be predicted with a maximum error of 13%.
[0051]
[Table 7]
[0052]
Example 2 (Example in which prediction accuracy is improved by calculating a cooling rate for each welding pass)
In the same manner as in Example 1, the toughness value of the original part (Table 3) and the toughness value of the reheated part (Table 4) at each cooling rate were obtained in advance, and further when welding was performed under various welding conditions. The area ratio (Table 5) of the reheat part and the raw material part is obtained.
[0053]
And from the cross-sectional photograph of the welded part obtained under welding conditions 2 (heat input: 30,000 J / cm, plate thickness: 20 mm t , interpass temperature: 350 ° C.) in Table 5, two passes of the final pass and the pre-final pass The area ratio of the reheated part and the original part was determined. The results were as shown in Table 8.
[0054]
[Table 8]
[0055]
Next, the cooling rate of each pass was predicted by solving the equation (2). The thermal conductivity and density were determined using a database prepared in advance from the base material component and the wire component.
[0056]
When the calculation was performed by dividing the weld metal part and the base metal part into meshes, the cooling rate of the final pass was 4.1 ° C./sec.
Cooling rate of last pass: 4.3 ° C / sec
Got. The mesh size of the weld metal part was 2 mm, the mesh size of the base metal part was increased in proportion to the distance from the weld metal part, and the mesh division method was an orthogonal lattice system.
[0057]
Note that the accuracy of cooling rate prediction and the time required for calculation can be changed by changing the mesh size. The finer the mesh size, the better the accuracy, but the longer the time required for calculation. In order to ensure sufficient prediction accuracy, it is desirable to divide the mesh size into at least the number of passes in the width direction and height direction of the weld metal. On the other hand, however, the prediction accuracy is almost saturated when the mesh size is about the plate thickness / (number of passes x 30), and even if the mesh is divided finer than that, the estimated time only extends unnecessarily. Any further subdivision is meaningless.
[0058]
Next, the cooling rate predicted by the above calculation was compared with the mechanical properties of the reheat part and the raw material part. At this time, if the cooling rate does not exist in the database to be collated, the mechanical characteristics were predicted by linear interpolation in the same manner as described in the first embodiment. The results are shown in Table 9.
[0059]
[Table 9]
[0060]
Finally, the mechanical properties of the reheated part and the original part were over-averaged according to the area ratio of the reheated part and the original part, and the mechanical characteristics at the desired site were predicted. The prediction result was 118.4 J. The prediction error was 5.3%. This prediction error is further smaller than the prediction error 7% in the welding condition 2 in the first embodiment. Therefore, in multi-pass welding, the accuracy is estimated by predicting from the cooling rate in each pass. It can be seen that it can be further increased.
[0061]
Therefore, according to the present invention, when the target mechanical characteristics of the weld metal according to the application and purpose are determined, the mechanical characteristics are predicted by the method as described above, and the predicted mechanical characteristics are the target. If the characteristics are not met, the welding conditions (preliminary heat input, interpass temperature, etc.) set in advance are changed and the mechanical characteristics of the weld metal are predicted again. By repeatedly performing the calculation until the metal characteristics are satisfied, it is possible to determine the welding conditions that satisfy the target weld metal characteristics.
[0062]
【Effect of the invention】
The present invention is configured as described above, and can easily and accurately predict the mechanical properties of the weld metal after welding, or, further, the mechanical properties of the weld metal can be achieved by simple means. It was possible to determine the optimum welding conditions that satisfy the requirements.
[Brief description of the drawings]
FIG. 1 is an example of a flowchart showing a procedure for carrying out a method of the present invention.
Claims (5)
溶接を行う際の板厚、入熱量、パス間温度の３項目の溶接条件と、溶接金属の再熱部および原質部の夫々について面積割合との関係を示す第１のデータベースを用意する工程と、
前記溶接条件における冷却速度と、溶接金属の再熱部および原質部の夫々について機械的特性との関係を示す第２のデータベースを用意する工程と、
前記溶接条件において、下式（１）によって最終パスの冷却速度を算出する工程と、
前記溶接条件と前記第１のデータベースとを照合することにより溶接金属の再熱部および原質部の夫々の面積割合を得る工程と、
前記算出された冷却速度と前記第２のデータベースとを照合することにより、溶接金属の再熱部および原質部の夫々の機械的特性を得る工程と、
前記溶接金属の再熱部および原質部の夫々の面積割合と機械的特性から、溶接金属の機械的特性を予測する工程と、
を包含することを特徴とする溶接金属の特性予測方法。
Ｑは入熱量、θ0はパス間温度、ｈは母材板厚であり、
他の定数は、本願明細書の表１に記載のとおりである。A method for predicting the mechanical properties of a weld metal formed by welding using a specific base material and a specific wire,
Thickness when performing the welding, heat input, a step of preparing a welding condition of three items interpass temperature, the first database indicating a relationship between the respective area ratios of the reheat section and unaffected zone of the weld metal When,
Preparing a second database indicating the relationship between the cooling rate in the welding conditions and the mechanical properties of each of the reheated portion and the primary portion of the weld metal;
In the welding conditions, a step of calculating the cooling rate of the final pass by the following formula (1),
Obtaining the respective area ratios of the reheated part and the primary part of the weld metal by comparing the welding conditions with the first database;
By matching with the calculated cooling rate and the second database, and obtaining the mechanical characteristics of each of the reheat section and unaffected zone of the weld metal,
Predicting the mechanical properties of the weld metal from the respective area ratios and mechanical properties of the reheated part and the primary part of the weld metal;
A method for predicting the properties of a weld metal, comprising:
Q is the amount of heat input, θ 0 is the interpass temperature, h is the base metal plate thickness,
Other constants are as described in Table 1 of this specification.
溶接を行う際の板厚、入熱量、パス間温度の３項目の溶接条件と、溶接金属の再熱部および原質部の夫々について面積割合との関係を示す第１のデータベースを用意する工程と、
前記溶接条件における冷却速度と、溶接金属の再熱部および原質部の夫々について機械的特性との関係を示す第２のデータベースを用意する工程と、
前記溶接条件において、下式（２）によってパス間の冷却速度を算出する工程と、
前記溶接条件と前記第１のデータベースとを照合することにより、溶接金属の再熱部および原質部の夫々の面積割合を得る工程と、
前記算出された冷却速度と前記第２のデータベースとを照合することにより溶接金属の再熱部および原質部の夫々の機械的特性を得る工程と、
前記溶接金属の再熱部および原質部の夫々の面積割合と機械的特性から、溶接金属の機械的特性を予測する工程と、
を包含することを特徴とする溶接金属の特性予測方法。
Ｈはエンタルピー、Ｋは熱伝導度、ｑは単位体積当たりの溶接トーチからの入熱、
Ｔは温度、ｖは溶接速度、ρmは密度である。A method for predicting the mechanical properties of a weld metal formed by welding using a specific base material and a specific wire,
A step of preparing a first database showing the relationship between the welding conditions of the three items of plate thickness, heat input, and interpass temperature during welding, and the area ratio for each of the reheated part and the original part of the weld metal When,
Preparing a second database indicating the relationship between the cooling rate in the welding conditions and the mechanical properties of each of the reheated portion and the primary portion of the weld metal;
In the welding conditions, a step of calculating the cooling rate between path by the following equation (2),
By collating the said welding condition and said first database, and obtaining the area ratio of each of the reheat section and unaffected zone of the weld metal,
Obtaining the respective mechanical properties of the reheated part and the raw part of the weld metal by comparing the calculated cooling rate with the second database;
Predicting the mechanical properties of the weld metal from the respective area ratios and mechanical properties of the reheated part and the primary part of the weld metal;
A method for predicting the properties of a weld metal, comprising:
H is enthalpy, K is thermal conductivity, q is heat input from the welding torch per unit volume,
T is temperature, v is welding speed, and ρ m is density.
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| JP6459877B2 (en) * | 2015-09-25 | 2019-01-30 | 新日鐵住金株式会社 | Method for deriving fracture limit line of welded portion, method for manufacturing member having welded portion, program, and computer-readable recording medium recording program |
| JP7469671B2 (en) * | 2020-12-17 | 2024-04-17 | 日本製鉄株式会社 | Method for calculating deformation resistance curve of welded portion, program for calculating deformation resistance curve of welded portion, and device for calculating deformation resistance curve of welded portion |
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