Characteristic Evaluation Based on the Heat Treatment Conditions of Super Duplex Stainless Steel with 0.2% N as an Additive - Part 1: Mechanical Properties and Microstructure

J. Ocean Eng. Technol. 2008;22(4):46-50.

Ahn Seok-Hwan,Kang Heung-Joo,Nam Ki-Woo

School of Mechanical Engineering Pukyong National University,Busan Maritime High School,Division of Materials Science and Engineering Pukyong National University

0.2% N을 첨가한 수퍼 2상 스테인리스강의 열처리 조건에 따른 특성 평가 - 제1보: 기계적 특성 및 미세조직

안석환,강흥주,남기우

부경대학교 기계공학부,부산해사고등학교,부경대학교 신소재공학부

Keywords: Super duplex stainless steel, Mechanical property, Heat treatment condition, Microstructure

핵심용어: 수퍼 2상 스테인리스강, 기계적 특성, 열처리조건, 미세조직

Abstract

Super duplex stainless steel has along life in severe environments because of its strength and corrosion resistance. If 0.2$sim$0.3% Nitrogen in aninterstitial solid solution is added, the austenite structure is reinforced. This improves the solid solution hardening and the anticorrosionability. In this study, the mechanical properties and structures of the super duplex stainless steel with the 0.2% N additive were investigated to determine the effect of various volume fractions on the austenite phase. The various volume fractions and distributions of the austenite structure in the applied test specimens were obtained by changing the heat treatment temperature and cycle. The characteristics by amounts of the $sigma$ phase obtained from the precipitation heat treatment were alsoinvestigated. From the results, when the austenite volume fraction increases, the tensile strength decreases and elongation increases. And the $sigma$ phase was rapidly increased by increasing the heat treatment time. When the volume fraction of the $sigma$ phase increased, tensile strength increased.