YG20硬质合金/316L不锈钢焊接接头的焊后热处理组织研究
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摘要
以因瓦合金为中间层,对YG20硬质合金和316L不锈钢进行了激光焊接,并采用真空热压烧结炉对YG20/316L焊接接头进行了焊后热处理,研究分析了热处理后接头各区域的显微组织。结果表明:焊态试样的焊缝成形良好,无缺陷。焊态试样经1250℃保温不同时间后,靠近YG20侧的焊缝处都出现了断裂,断口齐平,无明显塑性变形,属于脆性断裂。经过热处理后,YG20侧热影响区均出现了钴粘结相的富集区域;同时WC晶粒正常长大,局部个别晶粒异常长大;因瓦合金显微组织发生了明显的变化,在晶体内部和晶界边缘析出了第二相。
Taking the invar alloy as intermediate layer, the laser welding of YG20 hard alloy and 316 L stainless steel was carried out, and the post weld heat treatment of YG20/316 L welded joints were carried out by using vacuum hot pressing sintering furnace. The microstructure of each region of the joint after heat treatment was studied. The results show that the welded specimens have good weld forming and no defects. After welding at 1250℃ for different time, the weld near YG20 side has fracture, and the fracture is even with no obvious plastic deformation, which belongs to brittle fracture. After heat treatment, the enrichment area of Co binding phase is found in YG20 heat affected zone. Meanwhile, WC grains grow normally and abnormal growth of local grains happens. The microstructure of invar alloy changes dramatically, and the second phase is precipitated in grains and grain boundaries.
Taking the invar alloy as intermediate layer, the laser welding of YG20 hard alloy and 316 L stainless steel was carried out, and the post weld heat treatment of YG20/316 L welded joints were carried out by using vacuum hot pressing sintering furnace. The microstructure of each region of the joint after heat treatment was studied. The results show that the welded specimens have good weld forming and no defects. After welding at 1250℃ for different time, the weld near YG20 side has fracture, and the fracture is even with no obvious plastic deformation, which belongs to brittle fracture. After heat treatment, the enrichment area of Co binding phase is found in YG20 heat affected zone. Meanwhile, WC grains grow normally and abnormal growth of local grains happens. The microstructure of invar alloy changes dramatically, and the second phase is precipitated in grains and grain boundaries.
引文
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[3] Prakash LJ. Application of fine grained tungsten carbide based cemented carbide[J].International Journal of Refractory Metals&Hard Materials,1995,13:257-264.
[4]周建华,顾敏.真空热处理对矿用硬质合金组织性能的影响[J].金属热处理,1998(5):19-20.
[5] Thakur D, Ramamoorthy B, Vijayaraghavan L. Influence of different post treatments on tungsten carbide-cobalt inserts[J].MaterialsLetters,2008,62:4403-4406.
[6]符夷雄,杨敏.热等静压对硬质合金性能的影响[J].凿岩机械气动工具,1995(4):16-20
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