FM 52M熔敷金属微观组织及热裂纹敏感性分析

Microstructure and Hot Crack Sensitivity Analysis of FM 52M Deposited Metal

为了明确Inconel 52M镍基合金熔敷金属开裂原因,采用开槽法制备Inconel 52M镍基合金熔敷金属横向可调拘束试样,采用万能试验机进行不同应变的加载,以分析熔敷金属热裂纹的敏感性,并采用扫描电镜和透射电镜分析熔敷金属微观组织。结果显示,690镍基合金的熔敷金属晶界上存在较多M23C6型碳化物,M23C6型碳化物与γ′形成黑白相间的层片状的共析组织,且与母相的晶界形成尖角。分析表明,由于与母相之间存在较大的错配度,从而导致其在应变作用下脱离母相,形成微孔洞,多个微孔洞连接后形成裂纹。可调拘束试验结果表明,当熔敷金属处于焊接热影响区时,若外加应变超过2.4%易产生热裂纹,随应变增大裂纹进一步扩展。

In order to find out the cracking reason of Inconel 52M Ni-base alloy deposited metal,the transverse adjustable restraint specimen of Inconel 52M Ni-base alloy deposited metal was prepared by slotting method.The sensitivity of hot cracking of the deposited metal was analyzed by loading different strains with universal testing machine,and the microstructure of the deposited metal was analyzed by scanning electron microscope(SEM)and transmission electron microscope(TEM).The results show that there are more M23C6 carbides on the grain boundary of 690 Ni-based alloy deposited metal.M23C6 carbides andγ′form a black-and-white lamellar eutectoid structure,and form a sharp angle with the grain boundary of parent phase.The analysis shows that there is a large degree of mismatch with the parent phase,which leads to its separation from the parent phase under the strain and the formation of micropores.After multiple micropores are connected,cracks are formed.The adjustable restraint test results show that when the deposited metal is in the welding heat affected zone,if the applied strain exceeds 2.4%,it is easy to produce hot cracks,and the cracks will further expand with the increase of strain.