Effects of Heat Treatment on Microstructure and Properties of 347 Stainless Steel Alloy Prepared by Wire Arc Additive Manufacturing

Abstract

In this study, 347 austenitic stainless steel parts were made by wire arc additive manufacturing process. Then, the effects of solution heat treatment at 1150°C for 3h followed by NbC stabilizing heat treatment at 950°C for 1h on the properties of the alloy were investigated. Results showed that after solidification, δ‐ferrite and NbC carbide particles were formed in the γ matrix while heat treatment eliminated the δ phase. Tensile test results showed that for the as‐prepared alloy yield strength varied between 336MPa and 352MPa, tensile strength between 559MPa and 589MPa, and elongation between 50 and 58%. However, heat treatment resulted in a 20‐22% decrease in yield strength, a 5‐10% decrease in tensile strength, and a 5% decline in elongation. The potentiodynamic (PD) polarization test results showed that the ICORR and the corrosion rate of the WAAM 347 stainless steel in the as‐prepared condition were separately 4.9 times and 5.6 times higher than the wrought alloy. After heat treatment, the ICORR increased from 5.84×10‐6 A/cm2 in the as‐prepared alloy to 6.68×10‐6 A/cm2, and the corrosion rate from 0.0678 to 0.0776 mm/y. This means that the heat treatment deteriorated the corrosion resistance of the WAAM 347 stainless steel alloy by about 14%.This article is protected by copyright. All rights reserved.