海工用H型钢Q355NE高温变形行为及其对微观组织的影响  

High temperature deformation behavior of Q355NE H-shaped steel for marine engineering and its influence on microstructure

作　　者：王敬忠[1] 姚慧琴 赵培林 李超 李远征[3] 杨西荣[1] WANG Jingzhong;YAO Huiqin;ZHAO Peilin;LI Chao;LI Yuanzheng;YANG Xirong(School of Metallurgy Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,Shaanxi,China;Laiwu Branch of Shandong Iron and Steel Co.,Ltd.,Jinan 250000,Shandong,China;Baoji Petroleum Steel Pipe Co.,Ltd.,Baoji 721000,Shaanxi,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055 [2]山东钢铁股份有限公司莱芜分公司,山东济南250000 [3]宝鸡石油钢管有限责任公司,陕西宝鸡721000

出　　处：《钢铁研究学报》2024年第6期766-775,共10页Journal of Iron and Steel Research

基　　金：陕西省重点研发计划资助项目(2022GY-132);山东省自然科学基金面上资助项目(ZR2020ME004)。

摘　　要：利用Gleeble-3800热模拟试验机,针对海工钢Q355NE在870~1 170℃和0.1~10 s-1条件下的热变形行为进行了深入研究,使用金相显微镜、电子背散射衍射以及透射电镜等技术手段,观察了不同热加工条件下试验钢的微观组织演变,引入无量纲Z参数,并基于加工硬化率与流变应力曲线,成功建立了Q355NE钢动态再结晶的临界应变模型。结果表明:Q355NE钢在热压缩过程中,其流变应力随变形温度的升高或应变速率的降低呈明显减小的趋势;同时,较高的变形温度和较低的应变速率更有利于动态再结晶特征的出现,计算了热变形激活能Q约为368.022 kJ/mol。建立了Q355NE钢在低lnZ条件下的临界应变模型。变形温度对Q355NE钢的组织与力学性能有显著影响。应变速率5 s-1条件下,在试验温度范围内随温度降低,铁素体晶粒的细化程度得到显著提升,大角度晶界比例增加,铁素体晶粒内部位错密度升高,有利于细小弥散Ti、Nb碳氮化物第二相粒子的析出,并有效抑制或避免魏氏组织形成,从而提高Q355NE钢的低温冲击韧性和强度。A deep study was conducted on the thermal deformation behavior of marine steel Q355NE under 870-1170 C and 0.1-10 s-1 conditions using a Gleeble-3800 thermal simulation testing machine.The microstructure evolution of experimental steel under different hot working conditions was observed using techniques such as metallographic microscopy,electron backscatter diffraction,and transmission electron microscopy,non-dimensional Z-parameters were introduced,and a critical strain model for dynamic recrystallization of Q355NE steel was successfully established based on work hardening rate and flow stress curve.The results show that during the hot compression process,the flow stress of Q355NE steel shows a significant decreasing trend with the increase of deformation temperature or the decrease of strain rate;meanwhile,higher deformation temperature and lower strain rate are more conducive to the appearance of dynamic recrystallization characteristics,and the calculated activation energy Q for hot deformation is about 368.022 kJ/mol.A critical strain model for Q355NE steel under low lnZ conditions has been established.The deformation temperature has a significant impact on the microstructure and mechanical properties of Q355NE steel.Under the condition of strain rate of 5 s-1,as the temperature decreases within the experimental temperature range,the refinement degree of ferrite grains is significantly improved,the proportion of large angle grain boundaries increases,and the dislocation density inside the ferrite grains increases.This is conducive to the precipitation of small and dispersed Ti and Nb carbon nitride second phase particles,and effectively suppresses or avoids the formation of Weinstein structure,thereby improving the low-temperature impact toughness and strength of Q355NE steel.

关 键 词：新型海工钢 Q355NE 形变热处理 临界应变模型 微观组织 

分 类 号：TG142.1[一般工业技术—材料科学与工程]