先进高强钢中的残余奥氏体:综述

Retained Austenite in Advanced High Strength Steels:a Review

铁路、建筑、机械等行业的发展对结构材料的安全性和轻量化提出了严格的要求,为此,需要开发高强韧先进高强钢。先进高强钢的特点是通过创新工艺设计实现多相微观结构的组合来满足现代工业对性能要求。目前,第三代先进高强钢主要包括相变诱导塑性(Transformation-induced plasticity,TRIP)钢、淬火-配分(Quenching and partitioning,Q&P)钢、中Mn钢和无碳化物贝氏体(Carbide-free bainite,CFB)钢,因为可以实现力学性能良好的匹配,被认为是未来轻量化结构材料。本文首先概述了近年来第三代先进高强钢的成分设计、固态相变以及组织调控等内容,特别是各种先进热处理工艺过程中合金元素配分对组织转变的作用规律。先进高强钢中复相组织一般包括马氏体、贝氏体、铁素体和残余奥氏体。残余奥氏体的体积分数和稳定性对先进高强钢的力学性能至关重要。接着本文介绍了影响钢中残余奥氏体稳定性的内在因素,并阐述了残余奥氏体对钢强塑性、韧性和疲劳性能的影响规律,为在多相微观组织中获得一定体积的亚稳态残余奥氏体以及探究微观组织与力学性能的关系提供参考。文章最后简述了先进高强钢的发展趋势,为提高金属材料力学性能探索新的方法。

The development of railways,buildings and machineries has necessitated the implementation of stringent requirements for the materials of safe and light-weight structures,which can be achieved through the development of strong and tough advanced high strength steels(AHSS).AHSS are characterized by the combinations of multi-phase microstructures achieved through innovative process designs to meet the performance requirements of modern industries.Currently,the third generation AHSS,which include transformation-induced plasticity(TRIP)steel,quenching and partitioning(Q&P)steel,medium Mn steel,and carbide-free bainitic steel,are considered promising candidates for lightweight structural applications,because they possess the ability to induce combinations of excellent mechanical properties.In this paper,firstly we review recent studies on alloying designs,solid-state phase transformations,microstructure adjustments of the third generation AHSS,in particular,the roles of advanced heat treatments,and partitioning of alloying elements in microstructure transformations.AHSS comprise microstructures of martensite,bainite,ferrite,and retained austenite.The amount and stability of retained austenite are crucial factors affecting the mechanical perfor-mance of AHSS.Secondly,the factors affecting the stability of retained austenite and the effect of austenite retention on strength,ductility,toughness,and fatigue properties are discussed.This paper would provide a reference to future research on obtaining a specific volume of metastable retained austenite in multiphase microstructures and exploring the relationship between microstructures and mechanical properties.Finally,the development trend of AHSS is briefly introduced for exploring new methods to improve the mechanical properties of metals.