Effect of Solution Treatment on Microstructures and Mechanical Properties of High Nitrogen Stainless Steel

High nitrogen stainless steel has excellent mechanical and chemical properties. Cr-Mn-Mo high nitrogen stainless steel with a nitrogen content of 0.54wt% was smelted by increasing the content of Cr and Mn at the nitrogen partial pressure of 80 000 Pa. The sample steels after hot rolling were held at 800, 900, 1000, 1100 and 1200 °C for 1, 2, 3, 4, and 5 h. Orthogonal analysis was carried out to study the microstructure, yield strength, tensile strength, elongation to fracture, reduction of area, and product of strength and plasticity under different temperatures and holding time, in order to find the best heat treatment temperature and time for the test steel. The results show that Cr2N precipitates in the samples without solution treatment and after solution treatment at 800 and 900 °C, and ferrite precipitates in the samples after solution treatment at 1200 °C. The materials treated at 1000 and 1100 °C are pure austenite. The specimen held at 1000 °C for 4 h has the best plasticity and high strength, and its section shrinkage and post-fracture elongation can reach 67.5% and 69.5%, respectively. The strength of the samples without heat treatment is the highest, and the reduction of section and elongation after fracture remains at 42% and 49.9%. The comprehensive mechanical properties of the samples held at 1000 °C for 1 h are the best, and the product of strength and plasticity can reach 58.59 GPa%. Copyright © 2022, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.