等离子喷焊IN625合金显微组织和力学性能分析

Microstructure and mechanical properties of plasma surfaced IN625 alloy

采用等离子喷焊机制备IN625合金,分析喷焊电流和后续热处理对IN625合金微观组织和力学性能的影响。结果表明:沉积态IN625合金的组织主要为有方向性的树枝状Laves相和奥氏体。随着喷焊电流的增加,沉积态IN625合金中树枝状Laves相数量增多且形态粗化,显微硬度由230 HV降低到190 HV。沉积态IN625合金经过1 180℃固溶处理后,部分Laves相溶解且形态细化,合金硬度与抗拉强度分别提高到310 HV和872 MPa。当固溶温度为1 200℃时,合金组织发生粗化,合金硬度降低。经过固溶时效处理的合金硬度与抗拉强度均低于固溶态。随着焊接电流的增大,固溶时效态IN625合金中树枝状Laves相数量增多,显微硬度下降。热处理前后喷焊合金的断裂形式主要为韧性断裂,热处理后断口中的韧窝尺寸较小,表现出良好的韧性。

IN625 alloy was prepared by plasma jet welding machine,and the effect of surfacing current and post heat treatment on microstructure and mechanical properties of the surfaced IN625 alloy was investigated. The results showed that the microstructure of the surfaced IN625 alloy consisted of the orientational dendrite Laves phase and austenite. The content of dendrite Laves was increased and its morphology was coarsened with the increase of surfacing current,the microhardness of the surfaced IN625 alloy was decreased from 230 HV to about 190 HV. The partial Laves in the surfaced IN625 alloy was dissolved and refined after solution treatment at 1 180 ℃,and the microhardness and the tensile strength were increased to 310 HV and 872 MPa,respectively. While the microstructure of the surfaced IN625 alloy was coarsened and the microhardness was decreased after solution treatment at 1 200 ℃.The microhardness and the tensile strength of the solution-aging treated IN625 alloy were lower than that of the solution treated alloy.The content of dendrite Laves in the solution-aging treated IN625 alloy was increased and its microhardness was decreased with the increase of welding current. The fracture mechanism of the surfaced IN625 alloy before and after heat treatment was ductile fracture,and the dimple in the fracture surface of heat treated IN625 alloy was presented as small size,showing good toughness.