调质工艺对620 MPa级高强钢组织及性能的影响

发布时间：2018-05-26 11:22

本文选题：离线淬火 + 在线淬火　；参考：《材料热处理学报》2017年09期

【摘要】：通过拉伸、系列冲击以及NDT落锤试验,采用SEM、TEM及EBSD技术手段,研究了轧后空冷+离线淬火+回火(QT)与轧后在线淬火+回火(DQT)工艺对620 MPa级高强钢组织及力学性能的影响。结果表明,调质后组织均为回火索氏体,但DQT工艺下组织粗大、扁平化且板条更加细长;淬火后试样在回火过程中,随着回火温度的升高,强度降低,塑性升高,且在线淬火试样纵向强度高于横向;在相同的回火工艺下,经DQT工艺处理的试样强度高于QT工艺处理的试样,但QT工艺下的调质钢断后伸长率、韧脆转变温度(FATT)及无塑性转变温度(NDTT)高于DQT工艺处理的试样。离线淬火工艺下的调质钢位错密度低、马氏体板条块尺寸小、残留奥氏体及大角度晶界含量高,该工艺处理后试样具有较低的韧脆转变温度和良好的止裂性能。
[Abstract]:By means of tensile test, series impact test and NDT drop weight test, the effects of air-cooled off-line quenching and tempering after rolling and on-line quenching and tempering on the microstructure and mechanical properties of 620 MPa grade high strength steel were studied by means of SEM-TEM and EBSD techniques. The results show that the microstructure of quenched and tempered samples are all tempered solids, but the microstructure is coarse, flattened and strip is more slender in DQT process, and the strength decreases and the plasticity increases with the increase of tempering temperature during quenching. The longitudinal strength of the on-line quenched specimen is higher than that of the transverse specimen, and the strength of the specimen treated by DQT process is higher than that of the sample treated by QT process under the same tempering process, but the elongation of quenched and tempered steel treated by QT process is higher than that of the quenched and tempered steel under the same tempering process. The ductile-brittle transition temperature (FATT) and the non-plastic transition temperature (NDTT) were higher than that of the samples treated by DQT process. The quenched and tempered steels have low dislocation density, small martensite lath size and high residual austenite and large angle grain boundary content. The samples treated by this process have lower ductile-brittle transition temperature and good crack arrest properties.
【作者单位】：首钢技术研究院;北京市能源用钢工程技术研究中心;
【分类号】：TG142.1;TG161

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