Effect of welding structure and δ-ferrite on fatigue properties for TIG welded austenitic stainless steels at cryogenic temperatures
✍ Scribed by Tetsumi Yuri; Toshio Ogata; Masahiro Saito; Yoshiaki Hirayama
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 1005 KB
- Volume
- 40
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
High-cycle and low-cycle fatigue properties of base and weld metals for SUS304L and SUS316L and the eects of welding structure and d-ferrite on fatigue properties were investigated at cryogenic temperatures in order to evaluate the long-life reliability of the structural materials to be used in liquid hydrogen supertankers and storage tanks and to develop a welding process for these applications. The S±N curves of the base and weld metals shifted towards higher levels, i.e., the longer life side, with decreasing test temperatures. High-cycle fatigue tests demonstrated the ratios of fatigue strength at 10 6 cycles to tensile strength of the weld metals to be 0.35±0.7, falling below those of base metals with decreasing test temperatures. Fatigue crack initiation sites in SUS304L weld metals were mostly at blowholes with diameters of 200±700 lm, and those of SUS316L weld metals were at weld pass interface boundaries. Low-cycle fatigue tests revealed the fatigue lives of the weld metals to be somewhat lower than those of the base metals. Although d-ferrite reduces the toughness of austenitic stainless steels at cryogenic temperatures, the eects of d-ferrite on high-cycle and low-cycle fatigue properties are not clear or signi®cant.