Effect of solution treatment on microstructure and properties of 00Cr32Ni7Mo3.5N

Abstract

ABSTRACT 00Cr32Ni7Mo3.5N parts were prepared by hot isostatic pressing (HIP) and forging process in this study. The effect of solution heat treatment on microstructure, mechanical properties and pitting resistance were investigated. Under solution treating at 1100°C, the phase constitution in HIP parts can be adjusted to comprise approximately 50% austenite (γ) and 50% ferrite (δ) phases with equiaxed structure, and this post-processing can meanwhile help to dissolve precipitated brittle σ phase. In comparison, the banded dual-phase structures in forged counterparts cannot be removed even after annealing at 1200°C. The desired phase proportion after solution treatment plus the equiaxed grains impart superior comprehensive performance to HIP parts with the tensile strength of 886 MPa, elongation of 48.0%, impact energy of 83 J, and pitting potential of 0.9659 V in neutral 3.5 wt-% NaCl solution. Based on this work, HIP seems to be a promising method to fabricate near-net-shape 00Cr32Ni7Mo3.5N parts. Highlights SAF3207 were prepared by HIP and was compared with its forging parts. HIP samples show equiaxed structure, while forgings are banded dual phase structures. Phase constitution can be adjusted to be approximately 50% austenite and 50% ferrite. The brittle σ phase can be completely removed after solution treatment. HIP seems a promising method to fabricate SAF3207 with high performance. GRAPHICAL ABSTRACT