高性能桥梁钢Q690qENH组织性能  

Microstructure and Properties of Q690qENH for High Performance Bridge Steel

作　　者：熊祥江[1] 史术华 范明[1] 彭宁琦[1] 彭清 李中平[1] 钱亚军[1] XIONG Xiangjiang;SHI Shuhua;FAN Ming;PENG Ningqi;PENG Qing;LI Zhongping;QIAN Yajun(Technology and Quality Department of Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,China;Five Meter Heauy Plate Plant of Hunan Valin Xiangtan Iron and Steel Co.,Ltd,Xiangtan 411101,China)

机构地区：[1]湖南华菱湘潭钢铁有限公司,湖南湘潭411101

出　　处：《金属材料与冶金工程》2020年第6期15-21,共7页Metal Materials and Metallurgy Engineering

摘　　要：为了加快目前我国高性能桥梁钢的研发与应用,采用低碳添加铌、钼、钒、铬等合金化元素及热机械控制轧制和离线回火热处理工艺研制高性能桥梁钢Q690qENH,并对轧态和400~700℃系列温度回火热处理后显微组织演变、力学性能和断裂韧性进行了系统研究。研究表明,轧态和回火热处理后均以粒状贝氏体和针状铁素体为主,轧态还存在少量铁素体组织,回火热处理过程中有大量析出相,且随回火温度提高,这些析出相更多更弥散,当回火温度提高到650℃时出现大量纳米级析出相,700℃时出现20~30微米的粗化析出相,且出现少量块状铁素体组织。同时在500~650℃区间进行回火热处理后各项性能优良,屈服强度719~754 MPa,抗拉强度841~852 MPa,屈强比0.85~0.90,断后伸长率>20%, Z向性能>70%,夏比冲击实验值在180 J以上,断裂韧性在-40℃低温环境下CTOD值在0.20 mm以上,属于韧性破坏断裂。In order to speed up the development and application of high performance bridge steel in our country,low carbon chemical composition with niobium,molybdenum,vanadium,chromium was adopted,as well as thermal mechanical control rolling and offline tempering heat treatment process,and systemic research was done on microstructure evolution,mechanical properties and fracture toughness in the as-rolled state and 400~700℃series temperature tempering heat treatment state.The research showed that granular bainite and acicular ferrite are principal in as-rolled state and after tempering heat treatment,and there are also a small amount of ferrite structure in as-rolled state and a large amount of precipitated phase during tempering heat treatment.With the increase of tempering temperature,these precipitates are more and more dispersed.When the tempering temperature increases to 650℃,a large number of nano precipitates appear,and at 700℃,there are coarse precipitates of 20〜30μm and a small amount of massive ferrite.At the same time,various properties are excellent after tempering heat treatment in the range of 500~650℃,such as yield strength 719~754 MPa,tensile strength 841~852 MPa,yield-tensile ratio 0.85~0.90,elongation after fracture>20%,Z-direction performance>70%,charpy impact experimental value above 180 J and fracture toughness at-40℃ CTOD value above 0.20 mm,which belongs to ductile fracture.

关 键 词：Q690qENH 回火 析出相 

分 类 号：TF[冶金工程] TG1[金属学及工艺—金属学]