激光焊接异种钢组织及显微硬度分析

Microstructure and microhardness analysis of laser welded dissimilar steel

采用激光摆动焊接方法焊接异种钢,利用JMATPro软件计算了母材3Cr13,VG10的平衡相图,通过XRD,SEM,EPMA等技术分别对焊缝、熔合区、热影响区的相组成和显微组织进行了分析,测定了焊接接头的显微硬度分布.试验结果表明,焊缝主要为α相和碳化物M7C3;从熔合线到焊缝中心,组织由平面晶逐渐变为胞状晶、胞状树枝晶、树枝状晶、柱状晶、等轴晶.焊缝组织存在显微偏析,其中C,Cr元素在晶界富集,Fe元素在晶内富集,同时在晶界处有条棒状的M7C3析出.熔合线附近的母材处有C迁移现象,其中3Cr13侧母材处有类针状马氏体组织产生,VG10侧熔合区存在非对流混合区,在该位置有块状、岛状组织嵌入母材,且在该组织上有片层状的碳化物生成.熔合线两侧的母材硬度值最大,焊缝区硬度变化较小,热影响区硬度随着远离焊缝中心距离的增加而逐渐减少.

After welding dissimilar steel by laser swing welding,the equilibrium phase diagrams of base 3Cr13 and VG10 were calculated by JMATPro software,and the phase composition and microstructure of weld,fusion zone and heat affected zone were analyzed by XRD,SEM,EPMA and other techniques.in addition,the microhardness distribution of welded joints was determined.The results show that the weld is mainly composed of phases and carbides M7C3,and from the fusion line to the weld center,the structure changes from plane crystal to cellular crystal,cellular dendrite,columnar crystal,dendritic crystal and equiaxed crystal.The microstructure of the weld exists micro-segregation,in which C and Cr elements are enriched at the grain boundary,Fe elements are enriched within the grains,and bar-like M7C3 precipitates at the grain boundaries.There is a C migration phenomenon at the base material of the fusion line near.Among them,acicular martensitic structure is generated on the 3Cr13 side,and the unmixed zone exists in the fusion zone on the VG10 side.At this position,the massive,island tissue is embedded in the base Material,and there are lamellar carbides on the structure.The hardness of the base metal on both sides of the fusion line is the largest,and the hardness of the weld zone changes little.The hardness of the heat affected zone decreases with the increase of the distance away from the weld center.