JPS6216749B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention can form a brazed part with high strength and excellent fatigue life. This relates to a low melting point Cu--Mn brazing filler metal with good wettability and fluidity. Conventionally, when manufacturing bits for drills, rock drilling, or cutting, when brazing cemented carbide (WC-Co alloy) chips to the base metal (steel material), Cu-Mn brazing filler metals were mainly used. and silver wax were used. Particularly recently, the above-mentioned Cu-Mn brazing filler metal has attracted attention as a new brazing filler metal to replace silver solder, and has come to be widely used. In particular, it can also be used for fluxless brazing in an inert gas atmosphere. (b) It is cheaper than silver solder or copper solder. (c) High brazing shear strength can be obtained. (d) It has good plastic workability, so it can be easily processed into thin wires and thin plates. This is due to the fact that it has many advantages as a brazing filler metal. For example, in rock drilling bits manufactured using the Cu-Mn brazing filler metal mentioned above, the drilling life is shortened due to the brazing part. This is determined not by chip loss, but by chip wear. For example, in the case of the above-mentioned bits, attempts have been made to increase the size of the cemented carbide chips that are brazed to extend the time it takes for them to wear out, thereby extending their service life. If the area of the brazed part becomes large, (a) there will be parts in the brazed part where the solder does not go around, or gas escape will be difficult, resulting in the formation of cavities. (b) They are required to be used under more severe conditions, and as a result, defects in the brazed parts are more likely to appear during use. (c) During brazing, not only does it take time to raise the temperature, but the temperature distribution also becomes uneven, resulting in poor workability. Problems such as these appeared. The inventors of the present invention have conducted studies to solve the above-mentioned problems that appear especially when the brazing area becomes large. The wax can be applied completely over the entire attachment surface. (b) While suppressing gas absorption during wax melting, improving the diffusion wettability of the wax will improve gas release. (c) Lowering the melting point of wax improves workability. Based on these conclusions, we conducted further research and determined that the composition of the brazing filler metal was as follows: Mn: 10-50%, Zn: 1-25%, Ni: 5-15%. , and, if necessary, one or two of Fe and Co: 5% or less, and further, if necessary, Al: 0.05 to 3%, Rare earth elements: 0.005 to 0.3 %, and the remainder is Cu and unavoidable impurities.The resulting Cu-Mn brazing filler metal has a low melting point and has good wettability and fluidity. What's more, we found that the brazed parts using this Cu-Mn brazing filler metal exhibit extremely high strength and excellent fatigue life. This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below. (a) Mn The Mn component has the effect of lowering the melting point of the brazing filler metal, but if its content is less than 10%, the melting point of the brazing filler metal will decrease.
Brazing workability deteriorates as the temperature exceeds 1000℃, while when the content exceeds 50%, not only does the melting point of the filler metal rise again to over 1000℃, but it also becomes difficult to melt the filler metal when manufacturing the filler metal. At the same time, the Mn yield was also very low, so the content was set at 10 to 50%. (b) Zn The Zn component lowers the melting point of the solder, reduces the solubility of gas in the molten solder during brazing, improves the fluidity and wettability of the solder, and oxidizes the molten solder. However, if the content is less than 1%, the desired effect cannot be obtained, while if the content exceeds 25%, the rolling or This not only reduces workability in processes such as wire drawing, but also increases Zn evaporation during brazing, making it more likely that defects will occur in the brazed part, so the content should be reduced from 1 to 25%. It was determined that (c) Ni The Ni component improves the heat resistance strength and corrosion resistance without reducing the ductility of the brazing filler metal.
For example, when a WC-Co alloy chip is brazed to a steel base metal, Co melts during brazing and crystallizes on the base metal, so that Co in the chip becomes a brazing material. It has the effect of suppressing the formation of a de-Co layer on chips that occurs as a result of replacing other components, but if the content is less than 5%, the desired effect cannot be obtained, while if the content exceeds 15%. Since the melting point of the brazing filler metal becomes higher than 1000°C and the brazing workability deteriorates, its content was set at 5 to 15%. (d) Fe and Co Since Fe and Co each have the same and equal effect as Ni, a part of Ni can be replaced with these components, but if they are added in excess of 5%, the brazing material As the melting point increases, the ductility and workability also decrease, so the upper limit was set at 5%. (e) Al The Al component has the effect of further improving castability during the production of brazing filler metal, preventing oxidation of the brazing filler metal during brazing, and further solid solution strengthening and slight precipitation strengthening of the brazing filler metal. However, its content is
If the content is less than 0.05%, the desired effect cannot be obtained; on the other hand, if the content exceeds 3%, the brazing material itself becomes brittle and the workability deteriorates.
Since the wettability of wax also decreases, its content was set at 0.05 to 3%. (f) Rare earth elements Rare earth elements have the effect of preventing oxidation of the wax during heating during brazing and further improving the wettability of the solder, but if the content is less than 0.005%, the desired oxidation resistance is not achieved. On the other hand, if the content exceeds 0.3%, it will not only be difficult to melt during manufacturing of the brazing filler metal, but also cause defects to occur in the ingot. It was set at 0.005-0.3%. In addition, Mg and Mg are added to the brazing filler metal of the present invention having the above composition as a deoxidizing agent for the purpose of improving melting and castability.
One or more of B, Li, and P, one or both of Si and Ti for the purpose of improving strength, and one or both of Sn and In for the purpose of improving corrosion resistance. If necessary, each of these components may be contained in a total amount not exceeding 3%, and the properties of the brazing material of the present invention are not impaired in any way by the inclusion of these components. Next, the Cu--Mn brazing filler metal of the present invention will be explained using examples. Example 1 When manufacturing a rock drilling bit by brazing a cemented carbide (WC-10% Co alloy) chip to a steel base metal in an Ar atmosphere, the chemical composition shown in Table 1 was used. Brazing was carried out using the brazing fillers 1 to 14 of the present invention and comparative brazing fillers 1 to 4 at the brazing temperatures shown in the table. Note that comparative brazing fillers 1 to 3 are conventional Cu--Mn brazing fillers, and comparative brazing filler metal 4 is a silver brazing filler metal. Next, five rock drilling bits obtained using the brazing fillers 1 to 14 of the present invention and comparative brazing fillers 1 to 4 were subjected to rock drilling until the bits became unusable (bit life). The perforation length was measured and the average value was determined. The average bit life (average drilling length) obtained as a result is
Shown in the table.

[Table] As shown in Table 1, the present invention brazing materials 1 to 14
Since all have low melting points, comparative brazing filler metals 1~
It is possible to braze at a lower brazing temperature compared to No. 3, and in addition, the bits using the brazing material of the present invention have extremely long holes compared to the bits using the conventional Cu-Mn brazing material and silver soldering material. It is clear that it shows the lifespan. Example 2 When manufacturing a dry drill bit by brazing a cemented carbide (WC-10% Co alloy) chip to a steel base using flux, a drill bit having the composition shown in Table 2 was used. Brazing was performed using the brazing materials 15 to 27 of the present invention and comparative brazing materials 4 to 6 at the brazing temperatures shown in the table. The comparative brazing fillers 5 and 6 are conventional Cu--Mn brazing fillers. Then, each of the five dry drill bits obtained using the brazing fillers 15 to 27 of the present invention and the comparative brazing fillers 4 to 6 was drilled into concrete by 40 mm each time until the bits became unusable. Measure the average drilling length (bit life),
Table 2 shows the average bit life.

[Table] As shown in Table 2, Example 2 showed the same results as Example 1, indicating that the properties of the brazing filler metal of the present invention are significantly superior in terms of brazing temperature and fatigue life. it is obvious. As mentioned above, the Cu-Mn brazing material of the present invention has a low melting point and good wettability and fluidity, so it can be used at low brazing temperatures, with good workability, and even when the brazing area is large. Brazing can be carried out with very few defects occurring in the brazed part, and the resulting brazed part has extremely excellent properties such as extremely high strength and excellent fatigue life.

Claims (1)

[Scope of Claims] 1 Mn: 10 to 50%, Zn: 1 to 25%, Ni: 5 to 15%, Cu and unavoidable impurities: the rest, (or more weight %). Low melting point Cu with good wettability and fluidity
-Mn-based brazing filler metal. 2 Mn: 10 to 50%, Zn: 1 to 25%, Ni: 5 to 15%, Al: 0.05 to 3%, Cu and unavoidable impurities: the remainder (more than % by weight). Low melting point Cu with good wettability and fluidity
-Mn-based brazing filler metal. 3 Mn: 10-50%, Zn: 1-25%, Ni: 5-15%, rare earth elements: 0.005-0.3%, Cu and unavoidable impurities: remainder, characterized by having a composition consisting of (more than % by weight) Low melting point Cu with good wettability and fluidity
-Mn-based brazing filler metal. 4 Mn: 10 to 50%, Zn: 1 to 25%, Ni: 5 to 15%, Al: 0.05 to 3%, rare earth elements: 0.005 to 0.3%, Cu and unavoidable impurities: remainder, (more than weight %) Low melting point Cu with good wettability and fluidity, characterized by having a composition of
-Mn-based brazing filler metal. 5 Mn: 10 to 50%, Zn: 1 to 25%, Ni: 5 to 15%, one or two of Fe and Co: 5% or less, Cu and unavoidable impurities: remainder, (more than weight %) Low melting point Cu with good wettability and fluidity, characterized by having a composition consisting of
-Mn-based brazing filler metal. 6 Mn: 10-50%, Zn: 1-25%, Ni: 5-15%, one or two of Fe and Co: 5% or less, Al: 0.05-3%, Cu and inevitable impurities: The remainder is low melting point Cu with good wettability and fluidity, characterized by having a composition consisting of (more than % by weight)
-Mn-based brazing filler metal. 7 Mn: 10-50%, Zn: 1-25%, Ni: 5-15%, one or two of Fe and Co: 5% or less, rare earth elements: 0.005-0.3%, Cu and inevitable impurities : Residual: Low melting point Cu with good wettability and fluidity, characterized by having a composition consisting of (more than % by weight)
-Mn-based brazing filler metal. 8 Mn: 10-50%, Zn: 1-25%, Ni: 5-15%, one or two of Fe and Co: 5% or less, Ai: 0.05-3%, rare earth elements: 0.005- Low melting point Cu with good wettability and fluidity, characterized by having a composition consisting of 0.3%, Cu and unavoidable impurities: (more than % by weight)
-Mn-based brazing filler metal.