An investigation of intergranular reheat cracking in the weld heat affected zone of TP321H stainless steel
Weld metal of a TP321H austenitic stainless steel pipe in a synthetic ammonia process pipeline, which served up to 4 years at 650℃ has been investigated experimentally in this study. The performance and microstructure of the weld metal were characterized by impact test, Vickers hardness test, optical microscopy (OM), and field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The results indicated that in synthetic ammonia process pipeline made of TP321H austenitic stainless steel, the microstructure of heat affected zone (HAZ) of pipe and elbow were austenite and a little twin crystal, the size of austenite grains was not uniform, microstructure of welding metal consisted of austenite and ferrite. Intergranular cracks extended along fusion line in welding joint. Lots of Ti(C, N) particles which precipitated along grain boundaries presented in the pipe side of HAZ, Cr-denuded zone appeared at grain boundary. The HAZ fractures showed intergralular feature, visible cavities and cracks were also presented. The average room impact energy of HAZ were 103 J, lower than that of base metal, which is 121 J. The hardness of welding joint, HAZ and base metal were about 252-272HV10, 224-256HV10, and 205-126HV10, respectively. Compared with base metal, hardness of HAZ and welding metal were higher. In this synthetic ammonia pipeline, cracks in the pipe side of HAZ of pipe and elbow welding joint were induced by stress relaxation.
TP321H HAZ Intergranular reheat crack Precipitation
Tao Chen Xuedong Chen Zhibin Ai Xiaoming Lian
National Technology Research Center on PVP Safety Engineering, Hefei General Machinery Research Institute, Hefei 230031, China
国际会议
2011 International Symposium on Structural Integrity 2011国际结构完整性学术研讨会--核工程结构完整性技术 ISSI 2011
合肥
英文
275-281
2011-10-27（万方平台首次上网日期，不代表论文的发表时间）