低合金超高强度钢中的相变及组织控制  

Phase transformation and microstructural control of low alloyed ultra-high strength steels

作　　者：乔志霞[1,2] 刘永长[1] 

机构地区：[1]天津大学材料科学与工程学院先进金属材料研究所,天津300072 [2]天津商业大学机械工程学院,天津300134

出　　处：《金属热处理》2015年第1期12-22,共11页Heat Treatment of Metals

基　　金：国家杰出青年科学基金(51325401);国际热核聚变试验堆(ITER)计划专项课题(2014GB125006);国家重点基础研究发展计划(973计划)(2014CB046805);国家自然科学基金(51474156)

摘　　要：概述了低合金超高强度钢中所涉及的相变及组织控制方法。马氏体相变是低合金钢获得超高强度的最基本的途径,通过优化热处理或形变热处理工艺获得细化的马氏体板条是保证超高强度的关键。马氏体钢中足够的塑韧性通过适度回火来保障,回火过程中组织控制的关键是避免脆性渗碳体碳化物的析出。对低合金超高强钢起重要作用的贝氏体主要有两种,下贝氏体和无碳化物贝氏体,其中下贝氏体主要与马氏体一起形成复合组织,细化马氏体板条尺寸。无碳化物贝氏体通过得到超细亚结构或超细板条而获得超高强度,同时利用贝氏体转变的不完全性获得稳定的高碳残留奥氏体来保证塑韧性。残留奥氏体在低合金超高强钢韧性改善方面起着重要作用,Q-P(或Q-P-T)钢和TRIP钢中较多的残留奥氏体可赋予低合金超高强钢超乎寻常的高塑韧性。Phase transformations,as well as the microstructural control methods,involved in the current existing low-alloyed ultra-high strength steel were reviewed. Martenste is the most primary strengthening structure for ultra-high strength steel and the refinement of martensite laths by optimizing heat treatment or thermal-mechanical processing is the key for achieving ultra-high strength by microstructural control. The impact toughness of martensitic low-alloyed ultra-high strength steel is provided by suitable tempering,during which brittle cementite should be avoided. Bainite is also very important for obtaining ultra-high strength in low-alloyed steel,including lower bainite and carbonite free bainite. Lower bainite inside martensite matrix favors to refining martensite laths by dividing prior austenite grains in advance.Carbon-free bainite with super-fine subunits can provide ultra-high strength. Retained austenite plays significant role for obtaining excellent impact toughness in low-alloyed ultra-high strength steels,the high fractions of retained austenite in Q-P( or Q-P-T) steels and TRIP steels provide exceptional toughness in them.

关 键 词：低合金超高强钢 马氏体 贝氏体 残留奥氏体 组织控制 

分 类 号：TG142.33[一般工业技术—材料科学与工程]