中南大学学报（自然科学版）2018，Vol.49Issue(2)：307-315,9.DOI:10.11817/j.issn.1672-7207.2018.02.007
超快冷工艺下X70管线钢微观组织及M/A岛演变
Microstructural characteristic and martensite-austenite constituent of X70 pipeline steel under ultra-fast cooling process
摘要
Abstract
Ultra-fast cooling (UFC) combined with laminar cooling techniques were used to process X70 pipeline strip with a thickness of 12.7 mm. The evolutional disciplines of microstructure and martensite-austenite (M/A) constituent were analyzed and discussed under different UFC processes, and optimal processing parameters of UFC were further determined. The results show that when ultra-fast cooling interrupt temperature decreases from 570 to 360℃, the microstructure of the steel sample can be categorized as follows: 1) quasi-polygonal ferrite+bainitic ferrite (BF)+ acicular ferrite (AF) +M/A constituent; 2) AF+BF+ M/A constituent; 3) AF+BF+lath bainite (LB)+M/A constituent. Specifically, when ultra-fast cooling interrupt temperature decreases from 570 to 440℃, the area fraction of M/A constituent does not change significantly and the length decreases obviously. When interrupt temperature further decreases to 360℃, the length of M/A constituent does not change obviously and the volume fraction decreases significantly. The tested steel exhibits the most excellent mechanical properties of tensile tests and Charpy impact tests under ultra-fast cooling interrupt temperature of 440℃. For the tested X70 pipeline steel, the optimum ultra-fast cooling processing parameters are concluded as follows: finishing rolling at 830℃+ultra-fast cooling to 410-470℃+laminar cooling to 320-370℃+coiling.关键词
超快冷/X70管线钢/显微组织/M/A岛/力学性能Key words
ultra-fast cooling/X70 pipeline steel/microstructure/M/A constituent/mechanical properties分类
矿业与冶金引用本文复制引用
王学强,袁国,赵金华,康健,邸洪双..超快冷工艺下X70管线钢微观组织及M/A岛演变[J].中南大学学报（自然科学版）,2018,49(2):307-315,9.基金项目
国家科技支撑计划项目(2012BAF04B01) （2012BAF04B01）
国家自然科学基金资助项目(51504063)(Project(2012BAF04B01) supported by the National Key Technologies R&D Program （51504063）
Project(51504063) supported by the National Natural Science Foundation of China) （51504063）
