Effects of Repeated Weld-Repairs on the Mechanical Propertiesof the HAZ in AISI 304 Stainless Steel Weld

• Main Authors: Shen-Peng Liao, 廖森鵬
• Other Authors: John Tsai
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/36657796316689274835

碩士 === 國立臺灣科技大學 === 機械工程系 === 96 === The effect of multiple thermal cycles related with repeated weld-repairs on the variation of hardness, microstructure and mechanical properties in the HAZ of AISI 304 stainless steel welds was investigated in this study. The welding procedures and parameters used in this work were designed to approach to the practical applications in the field. The first pass of welding was conducted by gas tungsten arc welding (GTAW) process and the remained passes were completed by shield metal arc welding (SMAW) process. After the final pass was finished, the weld metal was removed by grinding. Repeated procedures were conducted and lasted for five times. The results indicate that the low energy input of SMAW process had less influence on varying the grain size and hardness in the HAZ of 304 stainless steel weld. For the repaired welds, the tensile strength was less than that of the un-welded base metal, but still met the requirement of ASME code. In regarding to impact tests at low temperature down to -40℃, the impact values and lateral expansion of repeated weld-repairs specimens were not deteriorated by the multiple thermal cycles in comparison with un-welded base metal. Besides, the lateral expansions of repeated weld-repairs specimens were higher than ASME B31.3 code requirement. It shows the impact toughness and ductility of AISI 304 were not affected by repeated weld-repairs.