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V-Nb微合金化Q420B大规格角钢的连续冷却转变规律

Continuous cooling transformation law of V-Nb microalloyed Q420B large size angle steel

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利用热膨胀仪和Gleeble-3500热模拟试验机测试了 V-Nb微合金化Q420B大规格角钢在未变形(静态)和变形(动态)条件下连续冷却转变行为,利用光学显微镜观察了试验钢连续冷却后的组织形貌,并绘制了试验钢的静态和动态CCT曲线.结果表明,试验钢动态CCT曲线相比静态CCT曲线向左上方移动,说明变形加快了试验钢相变速度并提高了试验钢的相变开始和相变结束温度.此外,变形扩大了试验钢珠光体相变区域的同时减小了贝氏体相变区域.静态和动态连续冷却转变过程中,随着冷却速度的提高,试验钢的组织从铁素体和珠光体逐步向着贝氏体和在更快冷速条件下形成的马氏体发生转变,试验钢硬度值逐渐升高.试验钢在奥氏体未再结晶区变形后得到的组织比未变形时得到的组织均匀细小.冷却速度提高可以获得更低的相变温度Ar3和更细小的铁素体晶粒,与此同时贝氏体组织更加细小.
Continuous cooling transformation behavior of V-Nb microalloyed Q420B large angle steel was tested under undeformed(static)and deformed(dynamic)conditions by using thermal dilatometer and Gleeble-3500 thermal simulation machine.Microstructure of the tested steel after continuous cooling was observed by using optical microscope,and the static and dynamic CCT curves of the tested steel were plotted.The results show that the dynamic CCT curve of the tested steel moves to the upper left compared to the static CCT curve,indicating that the deformation accelerates the phase transformation of the tested steel and increases the starting and ending temperatures of the phase transformation.In addition,the deformation expands the pearlite transformation zone of the tested steel and reduces the bainite transformation zone.During the process of static and dynamic continuous cooling transformation,as the cooling rate increases,the microstructure of the tested steel gradually transforms from ferrite and pearlite to bainite and martensite formed under faster cooling rate conditions,and the hardness value of the tested steel gradually increases.Microstructure obtained after deformation of the tested steel in the austenitic unrecrystallized zone is uniformly finer than that obtained without deformation.An increase in the cooling rate results in a lower phase transformation temperature Ar3 and finer ferrite grains,while at the same time the bainite microstructure is finer.

V-Nb microalloyingQ420B large size angle steelcontinuous cooling transformationstatic CCT curvedynamic CCT curve

黄剑涛、张明赫、冯运莉、尹绍江、陈春生、王厚昕

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华北理工大学冶金与能源学院,河北唐山 063210

唐钢中厚板材有限公司,河北唐山 063600

中信金属宁波能源有限公司,浙江宁波 315899

V-Nb微合金化 Q420B大规格角钢 连续冷却转变 静态CCT曲线 动态CCT曲线

国家自然科学基金国家自然科学基金河北省自然科学基金河北省中央引导地方科技发展资金河北省科技重大专项

5190107851974134E2022209070236Z1003G21281008Z

2024

10.13251/j.issn.0254-6051.2024.07.018

金属热处理
北京机电研究所 中国机械工程学会热处理学会 中国热处理行业协会

金属热处理

CSTPCD北大核心
影响因子：0.546
ISSN：0254-6051
年,卷(期)：2024.49(7)