摘要
采用铌钛微合金化工艺在2250 mm热连轧板带生产线开发了屈服强度为550 MPa级高强耐候钢,通过拉伸实验、冲击实验和72 h周期浸润腐蚀实验对实验钢板的性能进行了分析,结合金相显微镜(OG)、电子背散射衍射(EBSD)、透射电子显微镜(TEM)和电化学工作站对实验钢板的显微组织和腐蚀行为进行了研究,结果表明:实验钢板屈服强度为550 MPa,韧脆转变温度低于-80℃,腐蚀速率为Q345B的50%,综合性能优异。显微组织由铁素体、珠光体和粒状贝氏体组成,铁素体平均晶粒为4.5μm,体积分数为64.8%,晶粒内存在高密度位错和纳米级铌钛复合析出相,晶粒细化对屈服强度的贡献为259 MPa。经过72 h周期浸腐蚀实验后,实验钢板的Cu在内锈层富集,Cr在外锈层富集,进一步促进致密锈层生成,提高锈层自腐蚀电位和阻抗,增强锈层对基体的保护作用。
A high strength weathering steel plate with a yield strength of 550 MPa was developed in a 2250 mm hot strip production line through Nb-Ti microalloying.The properties of the test steel plate were tested and analyzed through tensile tests,impact tests and 72 h periodic infiltration corrosion tests.The microstructure and corrosion behavior of the test steel plate were studied with OG,EBSD,TEM and electrochemical workstations.The results are as follows:the yield strength of test the steel was over 550 MPa,the ductile-brittle transition temperature was lower than-80℃,and the relative corrosion rate of Q345B was 50%,which indicated excellent comprehensive properties.The microstructure was composed of ferrite,pearlite and granular bainite.The average grain size of ferrite was 4.5μm,and its volume fraction was 64.8%.High-density dislocations and nanoscale Nb-Ti composite precipitates existed in the grains,and the contribution of grain refinement to the yield strength was 259 MPa.After a72 h periodic immersion corrosion test,Cu was enriched in the inner rust layer and Cr was enriched in the outer rust layer,which promoted the formation of a dense rust layer,improved the self-corrosion potential and impedance of the rust layer,and enhanced the protective effect of the rust layer on the matrix.
作者
李雄杰
何博
LI Xiongjie;HE Bo(Ma’anshan Iron and Steel Co.,Ltd.,Ma’anshan 243000,Anhui,China)
出处
《江西冶金》
2022年第2期24-29,共6页
Jiangxi Metallurgy
