激光热输入对激光增材修复1Cr17Ni2不锈钢组织与力学性能的影响

Effect of laser heat input on microstructure and mechanical properties of 1Cr17Ni2 stainless steel repaired by laser additive

在1Cr17Ni2不锈钢上进行激光增材修复镍基高温合金粉末试验,研究了激光热输入对1Cr17Ni2钢修复接头显微组织及力学性能的影响。结果表明,1Cr17Ni2钢激光增材修复接头分为熔覆区、热影响区和不锈钢基体,熔覆区上部为均匀分布的树枝晶结构,一次臂较为发达,且生长方向具有一致性,大致平行于熔覆高度方向生长,树枝晶尺寸随激光热输入的减小而逐渐减小,晶粒间的空隙逐渐增大;熔覆区中部和下部区域为短小的柱状枝晶结构,且生长方向具有一致性,随激光热输入的减小,尺寸略有减小。熔覆区主要由基体相γ、沿晶界析出的不规则δ相和MC相等组成;不锈钢侧热影响区主要由块状δ铁素体、奥氏体、马氏体及球状珠光体等组织构成,且与合金熔覆区存在着明显的分界线。随激光热输入的减小,熔覆区平均硬度呈现先增后减的趋势,在激光热输入为80 J/mm时,其硬度达到最大值330.64 HV0.2,较不锈钢基体提高了9.78%。

Experiment of 1Cr17Ni2 stainless steel repaired by laser additive Ni-based high temperature alloy powder was carried out.The effect of different laser heat input on microstructure and mechanical properties of the repaired 1Cr17Ni2 steel joints was studied.The results show that the laser additive repair joints of the 1Cr17Ni2 steel are divided into cladded zone,heat-affected zone and stainless steel matrix.The upper region of the cladded zone is uniformly distributed dendrite structure,and the primary arm is fully developed and its growth direction is consistent,which is roughly parallel to the height of cladding.The dendrite size decreases with the decrease of heat input and the gap between the dendrite grains increases.The middle and lower regions of the cladded zone are short columnar dendritic structure,and its growth direction is consistent,which size decreases slightly as the laser heat input decreases.The cladded zone is mainly composed of matrix phaseγ,irregular phaseδand MC precipitated along grain boundary.The heat affected zone of the stainless steel side is mainly composed of massiveδferrite,austenite,martensite and spherical pearlite,and there is a clear boundary with the cladded zone.With the decrease of laser heat input,the average hardness of the cladded zone increases at first and then decreases.When the laser heat input is 80 J/mm,the maximum hardness is 330.64 HV0.2,which is increased by 9.78%than that of stainless steel matrix.