Effect of displacement velocity on elastic plastic fracture toughness of SM490B carbon steel plate in 0.7 MPa hydrogen gas
Effect of displacement velocity on elastic plastic fracture toughness of SM490B carbon steel plate in 0.7 MPa hydrogen gas
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0.7 MPa氢气中位移速度对SM490B碳钢板弹塑性断裂韧性的影响
DOI：
10.1299/kikaia.79.1210
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
S. Matsuoka
中科院分区：
文献类型：
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作者：
Takuya Matsumoto;H. Itoga;Sana Hirabayashi;M. Kubota;S. Matsuoka
©2013日本机械学会在空气和0. 7 MPa氢气中研究了SM 490 B碳钢板的弹塑性断裂韧性JIc。JIc测试根据JSME标准JSME S 001（1981）进行。在氢气中，位移速度V = 2 × 10 mm/s时的JIC（JIC = 10.0 kJ/m）远小于在空气中，位移速度V = 2 × 10 mm/s时的JIC（JIC = 248.6 kJ/m）。空气中的JIc不符合有效性要求。在氢气中，令人惊讶的是，V的进一步降低并没有降低JIC，而是增加了JIC。在V = 2 × 10 mm/s的氢气中，JIC为60.9 kJ/m。空气和氢气中JIC的大小与断口形貌相对应。在V = 2 × 10 mm/s的空气中，疲劳预裂纹尖端形成一个临界拉伸区SZWc，随后形成韧窝。在V = 2 × 10 mm/s的氢气中，预裂纹尖端出现准解理和韧窝。在V = 2 × 10 mm/s的氢气中，裂纹尖端先形成SZWc，然后再形成韧窝。这种弹塑性断裂韧性的行为进行了分析假设HESFCG（氢增强连续疲劳裂纹扩展），这是由作者提出的解释在氢的存在下的疲劳裂纹扩展速率的加速。在0.7 MPa氢气中以V = 2 × 10 mm/s显示的弹塑性断裂韧性试验与在0.7 MPa氢气中以循环数n = 1和应力比R = 0显示的疲劳裂纹扩展试验相同，因此在0.7 MPa氢气中以V = 2 × 10 mm/s显示的JIc不是真实的弹塑性断裂韧性。结果表明，用0.7MPa氢气中V = 2 × 10 mm/s的断裂韧性试验可以确定0.7MPa氢气中真实的弹塑性断裂韧性。
©2013 The Japan Society of Mechanical Engineers The elastic-plastic fracture toughness, JIc, of SM490B carbon steel plate was investigated in air and 0.7 MPa hydrogen gas. JIc tests were conducted in accordance with the JSME standard, JSME S001 (1981). JIc was much smaller in hydrogen at a displacement velocity of V = 2 × 10 mm/s (JIc = 10.0 kJ/m) than in air at V = 2 × 10 mm/s (JIc = 248.6 kJ/m). JIc in air does not satisfy the validity requirement. In hydrogen, surprisingly, a further decrease in V did not decrease JIc, but increased it. JIc in hydrogen at V = 2 × 10 mm/s was 60.9 kJ/m. The large and small values of JIc in air and hydrogen corresponded to the fracture morphology. In air at V = 2 × 10 mm/s, a critical stretched zone, SZWc, was formed at the tip of the fatigue pre-crack, followed by dimples. In hydrogen at V = 2 × 10 mm/s, quasi-cleavage instead of SZWc and dimples were formed at the pre-crack tip. In hydrogen at V = 2 × 10 mm/s, SZWc was formed at the precrack tip, followed by dimples again. This elastic-plastic fracture toughness behavior was analyzed assuming HESFCG (hydrogen-enhanced successive fatigue crack growth), which is proposed by the authors to explain the acceleration of fatigue crack growth rate in the presence of hydrogen. The elastic plastic fracture toughness test shown in 0.7 MPa hydrogen gas at V = 2 × 10 mm/s is the same as that shown in a fatigue crack growth test in 0.7 MPa hydrogen gas at a number of cycles of n = 1 and stress ratio of R = 0; and thus JIc in 0.7 MPa hydrogen gas at V = 2 × 10 mm/s is not the real elastic-plastic fracture toughness. We conclude that the real elastic-plastic fracture toughness in 0.7 MPa hydrogen gas can be determined by fracture toughness testing in 0.7 MPa hydrogen gas at V = 2 × 10 mm/s.