低温回火对U20Mn高强贝氏体钢轨氢脆敏感性的影响  

Effect of low temperature tempering on hydrogen embrittlement susceptibility of U20Mn high strength bainitic steel rail

作　　者：张倩 刘丰收 许鑫 吴广 惠卫军[2] 张凤明[3] ZHANG Qian;LIU Feng-shou;XU Xin;WU Guang;HUI Wei-jun;ZHANG Feng-ming(Metal&Chemistry Institute,China Academy of Railway Sciences,Beijing 100081,China;School of Mechanical Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China;Technology Center of Inner Mongolia Baotou Steel Union Co Ltd,Baotou 014010,China)

机构地区：[1]中国铁道科学研究院集团有限公司金属及化学研究所,北京100081 [2]北京交通大学机械与电子控制工程学院,北京100044 [3]内蒙古包钢钢联股份有限公司技术中心,内蒙古包头014010

出　　处：《材料热处理学报》2023年第12期78-89,共12页Transactions of Materials and Heat Treatment

基　　金：中国铁道科学研究院集团有限公司科研项目(2020YJ084)。

摘　　要：利用氢热分析(TDS)试验研究了U20Mn贝氏体钢轨试样的氢吸附特征。通过电化学充氢和慢应变速率拉伸试验(SSRT)研究了低温回火对高强贝氏体钢轨氢脆敏感性的影响,采用扫描电镜(SEM)、透射电镜(TEM)、电子背散射衍射(EBSD)技术及X射线衍射仪(XRD)等研究了U20Mn贝氏体钢回火前后的显微组织的变化。结果表明:在同等氢含量时,回火后的U20Mn贝氏体钢轨氢脆风险比回火前降低了近两倍,即其氢脆敏感性大幅降低。SEM断口观察表明,SSRT充氢拉伸断口在回火前存在沿晶开裂趋势和少量的沿晶裂纹,回火后断口则主要为准解理断裂形式。回火后贝氏体钢轨氢脆敏感性显著降低主要与钢中块状残留奥氏体(M/A岛)、可动位错及小角度晶界等的数量降低以及组织稳定性提高等因素有关。The hydrogen adsorption characteristics of U20Mn bainite steel rail samples were studied using hydrogen thermal desorption spectroscopy(TDS)experiments.The effect of low temperature tempering on hydrogen embrittlement susceptibility of the high-strength bainite steel rail was studied by electrochemical hydrogen charging and slow strain rate tensile(SSRT)test.The microstructure changes of the U20Mn bainite steel before and after tempering were studied by means of scanning electron microscopy(SEM),transmission electron microscopy(TEM),electron backscatter diffraction(EBSD)technique and X-ray diffraction(XRD).The results show that at the same hydrogen content,the hydrogen embrittlement risk of tempered U20Mn bainite steel rails is reduced by nearly twice compared to before tempering,indicating a significant decrease in hydrogen embrittlement susceptibility.SEM fracture observation shows that there is a trend of intergranular cracking and a small amount of intergranular cracks in the SSRT hydrogen filled tensile fracture before tempering,while the fracture is mainly in the form of quasi cleavage fracture after tempering.The significant decrease in hydrogen embrittlement susceptibility of the bainitic steel rails after tempering is mainly related to factors such as the reduction of residual austenite(M/A islands),movable dislocations,and small angle grain boundaries in the steel,as well as the improvement of structural stability.

关 键 词：U20Mn高强贝氏体钢轨 氢脆敏感性 低温回火 

分 类 号：TG142.3[一般工业技术—材料科学与工程]