JPH0230800B2 - PURAZUMAFUNTAIYOSETSUNIKUMORYOFUKUGOYOSETSUZAI - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a welding material for forming a build-up layer having a composite structure consisting of a metal matrix and carbide ceramic particles as a dispersed phase by a plasma powder weld build-up method. [Prior Art] Forming a coating layer having a composite structure consisting of a metal matrix and ceramic particles as a dispersed phase on the surface of rolls such as rolling rolls, heat treatment furnace rolls, conveyor rolls, and other structural members. teeth,
This is an extremely effective method for improving the heat resistance, wear resistance, etc. of these members. Thermal spraying is exclusively used as a method for forming this coating layer. Industrially available thermal spraying materials include composite powders mainly made of carbide ceramics such as silicon carbide (SiC) and tungsten carbide (WC), and oxide ceramics such as alumina (Al ₂ O ₃ ) and zirconia (ZrO). is supplied to. [Problems to be solved by the invention] However, the coating layer (sprayed layer) formed by the thermal spraying method has poor adhesion strength and is easily peeled off by mechanical impact, so there are problems with stability and durability in actual use. be. In addition, the coating layer lacks homogeneity and density of the composite structure, so the metal-ceramic composite effect, especially the dispersion strengthening effect of ceramic particles, is insufficient, resulting in poor strength, wear resistance, and heat resistance in high temperature ranges. It is not possible to expect such an improvement effect on the various characteristics of . The present invention provides a composite welding material for plasma powder weld build-up in order to solve the above problems. [Means and effects for solving the problems] The present invention provides a welding material for plasma powder welding that consists of a metal component as a matrix and carbide-based ceramic particles as a dispersed phase. The blending ratio of ceramic particles is 20 to 80% by weight, and the metal content of the matrix is C: 0.08% or less, Si: 0.5 to 3%, Mn: 2% or less, Ni: 2 to 10.
%, Cr: 15-30%, Co: 20-40%, and the remainder substantially consists of Fe. In the composite welding material of the present invention, the ceramic particles serving as the dispersed phase are carbide ceramic particles.
Carbide ceramic particles are hard and have high strength.
It also has good wettability with metal matrices, making it an excellent dispersion-strengthening component. Preferred examples thereof include chromium carbide ( _Cr3C2 , _{Cr7C2 ,} etc.), tungsten carbide (WC), titanium carbide ₍ TiC), niobium carbide (NbC), silicon carbide (SiC), and the like. The reason for setting the blending ratio of the carbide ceramic particles as the dispersed phase (weight ratio in the mixture with the metal component as the matrix) to 20% or more is because if it is less than 20%, the dispersion strengthening effect will not be sufficient, and for example, the hardness This is because shortages etc. will occur. As the blending ratio increases, hardness, wear resistance, heat resistance, high-temperature strength, etc. improve due to dispersion strengthening effect, but when it exceeds 80%, adhesion between bead laminations becomes poor in multi-layer weld bead buildup. 80% is set as the upper limit because this causes problems such as poor welding workability and poor toughness of the built-up layer formed. Although the particle size of the carbide ceramic particles is not particularly limited, it is preferably about 50 μm or less in order to ensure sufficient dispersion-strengthening effect. It has a high effect of inhibiting dislocation movement within the layer, and it is possible to secure a higher level of strength in low temperature and high temperature ranges. On the other hand, the metal component that forms the matrix is Ni-Cr.
-Co-Fe alloy, and the reasons for limiting its composition are as follows. C: 0.08% or less C is an impurity element. In order to keep the matrix metal at a high melting point, the upper limit is set at 0.08%. Si: 0.5 to 3% or less Si is at least 0.5% from the viewpoint of ensuring the fluidity of the molten metal formed during weld overlay and deoxidizing effect.
% is required. However, if it exceeds 3%, the toughness of the matrix decreases, so the upper limit is set at 3%. Mn: 2% or less Like Si, Mn has a deoxidizing effect on molten metal, and also prevents the generation of harmful FeS by fixing S, an impurity in molten metal, as MnS. However, if the content increases, the amount of MnS remaining in the molten metal increases and the cleanliness of the matrix metal is impaired, so the upper limit is set at 2%. Cr: 15-30% Cr increases the oxidation resistance of the matrix metal.
For this effect to be sufficient, at least 15
% is required. The effect increases as the content increases, but if it exceeds 30%, the toughness decreases, so 30% is the upper limit. Ni: 2-10% Ni increases the toughness of the metal matrix and
Enhances oxidation resistance through interaction with Cr. It also has the effect of improving wettability with carbide ceramic particles, which are the dispersed phase, and increasing the density and homogeneity of the composite structure. If the content is less than 2%,
If the above effects are insufficient, and if the amount exceeds 10%, the melting point of the matrix will inevitably decrease. 2-10%
shall be. Co: 20-40% Co is required to be at least 20% in order to ensure high temperature strength of the matrix and wettability to carbide ceramic particles. The effect becomes stronger as the content increases, but when it exceeds 40%, the effect is almost saturated, so it is not economical to increase the content any further. Therefore, the upper limit is 40%. The particle size of the metal powder forming the matrix is not particularly limited, but in order to improve the homogeneity of the mixture with the ceramic particles, the particle size is preferably about 40 to 100 μm. The powder mixture may be used as a weld overlay material as it is, but since there is a large difference in specific gravity between metal particles and ceramic particles, it is necessary to use Ar gas as a carrier gas through powder feed piping during weld overlay construction. Separation and segregation of metal particles and ceramic particles may occur during the process of feeding the metal particles to the welding torch, or when dispersing them from the welding torch to the molten pool on the surface of the welding base material directly below.
In particular, this tendency becomes more pronounced as the powder particle size becomes finer. As a measure to prevent separation and segregation due to the difference in specific gravity of the powder mixture, it is extremely effective to use the powder mixture as granulated powder with a suitable particle size, preferably about 50 to 300 μm. The granulated powder is produced by a known granulation method, for example, by adding an appropriate sizing agent, such as wax such as paraffin, to a powder mixture in an appropriate amount (for example, 2 to 3 parts by weight per 100 parts by weight of the powder mixture). This is suspended in a dispersion medium such as alcohol or water to form a slurry, and then subjected to a wet spray dryer (spray dryer) to form a granulated powder.
After dewaxing, it is fired and then crushed into 300 to 60 mesh pieces using a crusher. The composite build-up layer formed on the surface of a member such as a roll by the plasma powder weld build-up method using the welding material of the present invention has a strong fusion bond relationship with the member surface, and can be used at high temperatures of 1200°C or higher. Also, its composite structure is homogeneous and dense, and has excellent heat resistance and oxidation resistance, as well as high hardness at high temperatures, and therefore high wear resistance even in high temperature ranges. Shows resistance. In addition, since the welding workability is good, it is possible to form a built-up layer having an arbitrary thickness depending on the application. [Example] [] Preparation of weld overlay material (1) Matrix metal powder particle size: 50 μm (2) Carbide ceramic powder and particle size:
_Cr3C2 , NbC, _SiC , 15μm. Homogeneous mixture of metal powder and ceramic powder
Add 3 parts by weight of paraffin to 100 parts by weight,
Slurry preparation (dispersion medium: methyl alcohol, solid content concentration: 60% by weight), granulation using a spray dryer (granulated powder particle size: 1 to 3.5 μm), dewaxing (Ar atmosphere, 600℃), calcination (Ar In the atmosphere,
1350~1450℃), and after crushing treatment, 50~
Obtain 300μm granulated powder. [] Execution of weld build-up Using the above granulated powder as welding material, heat-resistant steel plate (C: 0.08%, Cr: 27
%, Co: 40%, Ni: 17%, balance Fe), five layers of beads are piled up on the surface to form a built-up layer with a layer thickness of 15 mm. [] Quality of Overlay Layer After the above-mentioned overlay welding, test pieces were prepared and various tests were conducted to obtain the results shown in Table 1. In the table,
Trial numbers (No.) 1 to 8% are invention examples, and Nos. 101 to 110 are comparative examples. Among comparative examples No. 101 to 110, No. 101 to
No. 103 is an example in which the blended amount of carbide ceramic particles is insufficient or excessive, and Nos. 104 to 108 are examples in which the component composition of the matrix metal deviates from the specifications of the present invention. Further, No. 109 is an example of a build-up layer formed by thermal spraying, and No. 110 shows test results for a base material without a build-up layer. Also,
In the table, the "oxidation resistance" column is evaluated based on the amount of oxidation loss (mm/year) at 1200℃, and the value is 0.30mm/year.
If it is less than 0.3 mm/year, it is marked as "〇" (good), and if it exceeds 0.3 mm/year, it is marked as "x" (poor). In addition, "welding performance" is based on three or more layers of bead lamination (layer thickness 10 mm).
If the above) is possible, mark it as “〇” (good), and mark it as “3”.
Those in which layering was impossible (poor interlayer bonding) were determined to be "x" (defective). As shown in Table 1, the composite build-up layers (No. 1 to 8) formed using the welding material of the present invention are compared to the composite build-up layer (No. 109) formed by thermal spraying. death,
High adhesion strength to the base material, hardness in high temperature range,
It has excellent strength and oxidation resistance. Moreover, it has good weldability, is easy to build up in multiple layers, and can form a composite built-up layer having an arbitrary thickness depending on the application and usage conditions of the member. On the other hand, when the blending ratio of ceramic particles is insufficient (No. 101), the high temperature strength and compressive strength are low, and conversely, when the blending ratio is excessive (Nos. 102 and 103), weldability is poor. Furthermore, if the component composition of the matrix metal deviates from the specifications of the present invention, oxidation resistance may be insufficient, and even if the blending ratio of ceramic particles is sufficient, high temperature hardness is not so high, resulting in poor wear resistance. Decrease in material properties such as high-temperature compressive strength cannot be avoided, and in either case, the material properties are inferior to those of the composite overlay layer of the example of the present invention.

〔Effect of the invention〕

The composite overlay layer formed by the plasma powder welding overlay method using the welding material of the present invention has high adhesion strength to the base material surface, and has excellent strength in high temperature ranges, heat resistance, wear resistance, etc. ing. In addition, welding workability is good, and it is easy to form a thick build-up layer by multi-layer build-up. Therefore, it greatly contributes to improving and stabilizing the durability of rolls and other various members that require wear resistance, strength, heat resistance, etc. in high temperature ranges.

Claims (1)

[Scope of Claims] 1. Uniformity of the metal component serving as the matrix and the carbide ceramic particles serving as the dispersed phase in order to form a weld build-up layer having a composite structure consisting of a metal matrix and ceramic particles serving as the dispersed phase. In the composite welding material for plasma powder welding, which is a powder mixture, the blending ratio of carbide ceramic particles is 20 to 80% by weight, and the metal content is C: 0.08% or less, Si: 0.5 to 3%,
Mn: 2% or less, Ni: 2-10%, Cr: 15-30%,
A composite welding material for plasma powder welding, characterized in that it has a composition consisting of Co: 20 to 40% and the remainder substantially Fe.