一种新型镍铁基焊丝熔敷金属组织及性能研究

Microstructure and Property of Deposited Metal of A New Type of Ni-Fe Based Welding Wire

对一种700℃先进超超临界锅炉用新型镍铁基高温合金焊丝熔敷金属进行了研究。根据热力学模拟计算,其热力学稳态相包括γ基体、γ’、TiC、硼化物、M_(23)C_(6)相。根据模拟计算的熔敷金属连续冷却转变曲线和等温转变曲线,结合热物性分析,存在少量γ’相在冷却过程中形核。对焊丝钨极氩弧焊的熔敷金属进行表征,结果表明:凝固过程中由于C、Ti元素强烈向枝晶间偏析,导致凝固末期在枝晶间形成了一次TiC相,其他合金元素则无显著偏析,且焊丝熔敷金属中并无有害相析出。焊丝熔敷金属室温及高温力学性能较好,且相对较低的热膨胀系数能降低结晶裂纹的敏感性。

The deposited metal of a new type of Ni-Fe based welding wire for 700℃ advanced ultra-supercritical boiler was studied. The γ, γ’, TiC, boride, M23 C6 phases are equilibrium phases according to the thermodynamic calculation. There are only a little of γ’ phase in the as-welded deposited metal according to the CCT and TTT diagrams as well as DSC diagram.The characterization of deposited metal of the welding wire welded by TIG welding was carried out. The results show that the primary TiC phase precipitates between dendrites because of the interdendritic segregation of C and Ti, and the other alloy elements have little segregation and there is no harmful phase precipitation. The mechanical properties of the deposited metal at room temperature and high temperature are good, and the sensitivity of crystal cracks can be reduced because of the low thermal expansion coefficient.