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论文类型：期刊论文

发表时间：2018-10-01

发表刊物：METALS

收录刊物：SCIE

卷号：8

期号：10

ISSN号：2075-4701

关键字：austenitic stainless steel; repeated welding; heat-affected zone; Gleeble weld-simulator; microstructure; mechanical properties

摘要：Heat-affected zone (HAZ) of welding joints critical to the equipment safety service are commonly repeatedly welded in industries. Thus, the effects of repeated welding up to six times on the microstructure and mechanical properties of HAZ for AISI 304N austenitic stainless steel specimens were investigated by a Gleeble simulator. The temperature field of HAZ was measured by in situ thermocouples. The as-welded and one to five times repeated welding were assigned as-welded (AW) and repeated welding 1-5 times (RW1-RW5), respectively. The austenitic matrices with the delta-ferrite were observed in all specimens by the metallography. The delta-ferrite content was also determined using magnetic and metallography methods. The delta-ferrite had a lathy structure with a content of 0.69-3.13 vol.%. The austenitic grains were equiaxial with an average size of 41.4-47.3 mu m. The ultimate tensile strength (UTS) and yield strength (YS) mainly depended on the delta-ferrite content; otherwise, the impact energy mainly depended on both the austenitic grain size and the delta-ferrite content. The UTS of the RW1-RW3 specimens was above 550 MPa following the American Society of Mechanical Engineers (ASME) standard. The impact energy of all specimens was higher than that in ASME standard at about 56 J. The repeated welding up to three times could still meet the requirements for strength and toughness of welding specifications.