Fracture toughness of cold worked and simulated heat affected structural steel
Fracture toughness of cold worked and simulated heat affected structural steel
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DOI：
10.1016/s0013-7944(97)00100-8
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发表时间：
1998
影响因子：
5.4
通讯作者：
K. Homma;C. Miki;Hang Yang
中科院分区：
文献类型：
--
作者：
K. Homma;C. Miki;Hang Yang
对冷加工和焊接对断裂韧性的影响进行了研究，探讨了冷加工构件焊接部位断裂韧性的综合影响。已知冷加工钢的断裂韧性会因应变时效而下降，并且在热影响区（HAZ）也会下降。在本试验研究中，采用模拟热影响区试样进行热处理前预应变的CTOD试验。虽然多道次焊接在热影响区产生复杂的组织分布，但采用两种类型的热循环来模拟热影响区。一是模拟临界间再加热粗晶HAZ (IRCG HAZ)，这是局部脆性区退化最严重的部分。另一种是模拟亚临界HAZ (SC HAZ)，这是HAZ中退化最小的部分。在这两类模拟组织中，从断裂力学的角度讨论了冷加工的影响。可以看出，IRCG HAZ的断裂韧性较低，该区域的断裂韧性不随预应变的增加而变化。SC热影响区断裂韧性不像IRCG热影响区那么重要，而是受到热处理前预应变的强烈影响。
Deterioration of fracture toughness due to both cold working and welding are studied to investigate the combined effect which is seen in the welded part of cold worked members. It is known that fracture toughness is degraded in cold-worked steels by strain aging and is also degraded in the heat affected zone (HAZ). In this experimental study, CTOD tests are carried out using simulated HAZ specimens which are pre-strained before heat treatment. Although multi-pass welding produces a complex distribution of microstructures in HAZ, two types of thermal cycles are used to simulate the HAZ. One is to simulate intercritically reheated coarse grain HAZ (IRCG HAZ), the most degraded part in the local brittle zone. Another is to simulate subcritical HAZ (SC HAZ), the least degraded part in HAZ. In these two types of simulated microstructures, the effects of cold working are discussed based on fracture mechanics. It can be observed that the fracture toughness in IRCG HAZ is fairly low and the variation of fracture toughness with increasing pre-strain does not exist in that particular region. The fracture toughness in SC HAZ is not so crucial as seen in IRCG HAZ, but is strongly affected by pre-strain before heat treatment.