1前言近年来,人们非常关注高级别石油、天然气管线钢,如API120。高级别管线钢需要精确的化学成分设计和获得以剪切转变机制为主的奥氏体转变工艺,如下贝氏体和板条马氏体转变工艺,以获得高强度、韧性和焊接性能的钢材。但是,低碳HSLA钢的连续相变和微观结构比高碳和中碳钢更复 1 Introduction In recent years, people have paid great attention to high-grade oil and gas pipeline steel, such as API120. High-grade pipeline steels require precise chemical composition design and an austenitic transformation process that is dominated by shear transfer mechanisms such as bainite and lath martensitic transformation to obtain steels of high strength, toughness and weldability . However, the continuous transformation and microstructure of low-carbon HSLA steels are more complex than those of high-carbon and medium-carbon steels