Regular Article

Abnormal toughness characteristics and fracture model in simulated welding HAZ of 5%Ni Steel

¹ Taiyuan University of Technology, College of Material Science and Technology, Taiyuan 030024, PR China
² Key laboratory of interface science and engineering in advanced materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, PR China

^* e-mail: dingmin415@126.com

Received: 14 February 2020
Accepted: 11 June 2020

Abstract

The toughness property of the coarse grained heat affected zone had become much worse since the large heat input welding was applied in HSLA for improving welding efficiency and reducing welding costs. Unlike previous investigations of the decreasing fracture toughness with heating time, the toughness of coarse grained heat affected zone increases in long heating time. Based on microstructure and mechanical properties, very remarkable impact toughness was obtained when the t_8/5 was 80 s: toughness of 171 J. The toughness improvement initiates not from inclusions but directly from the microstructure of substrate. The microstructure type and inclusion level will compete to dominate the toughness of the 5% Ni steel.