对高炉布料槽失效部件挂臂35CrMo的表面形貌、组织、成分、物相和硬度,以及高炉气氛进行了测试分析,结果显示失效部件表面发生严重开裂,表层组织Fe3C质量分数达到87.06%,表层碳质量分数达到6.24%,远远高于正常的35CrMo基体,HV0.2达到600,高炉煤气气氛分析发现布料槽服役环境存在高温和渗碳气氛。综合分析,布料槽挂轴在服役过程中发生了明显的金属碳化现象,主要过程为高炉活性碳气氛和高温造成游离状态的碳原子在表面沉积,并向基体扩散,造成金属高温碳化和表面脆化,诱发表层金属内部产生孔洞和缺陷,高温碳化在裂纹两侧继续进行,造成失效部件产生高温碳化腐蚀沟,导致设备发生失效。
The failure behavior of chute feeder suspension arm 35CrMo in blast furnace was researched through the surface observation,microstructure analysis,composition testing,XRD phase identification,micro-hardness test and analysis of fumes.The results show that there are serious alligator cracks in the surface of suspension arm,and the weight percentage of Fe3C in surface reaches 87.06 %,where C percentage composition is 6.24%.The micro-hardness is HV0.2600,while HV0.2200 in the matrix of 35CrMo suspension arm,and the high temperature and carburizing atmosphere are found in the blast furnace fumes.The process of failure includes several steps as follows.Firstly,the transfer of C in blaster atmosphere into the metal.phase and oversaturation on the metal secondly,formation of cementite M3C on the surface which acts as a barrier for further carbon ingress thirdly,M3C becomes instable and decomposes according to M3C →C＋3M fourthly,the surface becomes embrittlement and generates holes on the surface.finally,the crack on the surface formed in effect of thermal-shock and burdening stress,and the process of carburization will go on corroding on the both side of crack,which causes the failure of chute feeder suspension arm at last.
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