Effect of Solution and Double-Stage Aging Treatment on the Microstructure and Mechanical Properties of CMT-WAAM Inconel625 Structural Components

Abstract

This study was conducted on the quality control of Inconel625 alloy thin-walled structural components by CMT-WAAM (Cold Metal Transfer Based Wire and Arc Additive Manufacture) process. The solid solution + two-stage aging treatment process was proposed for the heat treatment of thin-walled parts. The effect of solid solution treatment temperature on the microstructure and mechanical properties of thin-walled parts was studied under the same aging treatment conditions. The experimental results show that the deposited microstructure of Inconel625 thin-walled structural parts is mainly columnar dendrites, which grow epitaxially along the deposition direction. The basic microstructure of specimen is γ-Ni solid solution, and many blocky or chain-like Laves phases are distributed in the grains and grain boundaries. After solid solution and two-stage aging treatment, the Laves phase of the specimen dissolves back, δ phase precipitates and significant changes in mechanical properties. With the increase of solution treatment temperature, the Laves phases dissolve gradually, accompanied by δ phases precipitation. As the solid solution treatment temperature increases, the Laves phase gradually dissolves back, accompanied by δ Phase precipitation. When the solid solution treatment temperature rises to 1200 °C, the Laves phase is completely dissolved, δ The phase disappears and the grain size significantly increases. As the solution treatment temperature increases, the microhardness and tensile strength show a trend of first increasing and then decreasing, while the yield strength shows no significant change.

Graphical Abstract