Effect of zirconium addition on the austenite grain coarsening behavior and mechanical properties of 900 MPa low carbon bainite steel

Jia Guo1), Aimin Guo1), Hui Guo1), Ying Wang2), Jing Li1), and Xinlai He1) 1) School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 2) School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China

摘 要：The ultra-fine bainitic microstructure of a 900 MPa low carbon bainitic Cu-Ni-Mo-B steel was obtained by a newly de-veloped relaxation precipitation control （RPC） phase transformation processing. In a pan-cake like prior-austenite grain, the micro-structure consisted of lath bainite, a little of abnormal granular bainite, and acicular ferrite. The effect of zirconium carbonitrides on the austenite grain coarsening behavior was studied by transmission electron microscopy （TEM）. The results show that, the lath is narrower with increasing cooling rate. The ratio of all kinds of bainitic microstructure is proper with the intermediate cooling rate; and Zr-containing precipitates distribute uniformly, which restrains austenite grain growing in heat-affected welding zone.

关键词：