Effect of alloy design on improving toughness for X70 steel during welding
Effect of alloy design on improving toughness for X70 steel during welding
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DOI：
10.1016/j.matdes.2015.09.073
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发表时间：
2015-12-25
影响因子：
8.4
通讯作者：
Li, Huijun
中科院分区：
文献类型：
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作者：
Zhu, Zhixiong;Han, Jian;Li, Huijun
为了确定和确定 Ti 的最佳合金设计，使用夏比 V 型缺口 (CVN) 测试和裂纹尖端张开位移 (CTOD) 测试评估了 Ti/N 比范围为 1.9 至 4.9 的 API 5L 级 X70 钢的模拟粗晶热影响区 (CGHAZ) 韧性。利用 Gleeble 3500 热机械模拟器来生成等效热输入为 2.5 kJ/mm 的模拟 CGHAZ。使用光学显微镜（OM）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）检查包括原奥氏体晶粒尺寸和析出物的CGHAZ微观结构。结果表明，不同Ti/N比例的模拟CGHAZ中的显微组织成分由贝氏体铁素体和少量马氏体-奥氏体CM-A)成分组成。在研究的Ti/N比范围内，对析出物的统计分析表明，Ti/N比对平均析出尺寸影响不大，平均析出尺寸控制在较窄的范围内（52-57 nm）。然而，在接近化学计量的 Ti/N 比率下，模拟 CGHAZ 中析出物的较高数密度肯定有助于获得更细的奥氏体晶粒尺寸，从而提高 CGHAZ 韧性性能。 (C) 2015 Elsevier Ltd. 保留所有权利。
To identify and determine the optimal alloy design of Ti, the toughness in simulated coarse-grained heat affected zone (CGHAZ) of API 5L grade X70 steels with Ti/N ratios ranged from 1.9 to 4.9 was evaluated using Charpy V-notch (CVN) testing and crack tip opening displacement (CTOD) testing. A Gleeble 3500 thermo-mechanical simulator was utilised to produce the simulated CGHAZ with equivalent heat input of 2.5 kJ/mm. The CGHAZ microstructures including prior austenite grain size and precipitation were examined using optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the microstructural constituents in the simulated CGHAZ for different Ti/N ratios consisted of bainitic ferrite and a small amount of martensitic-austenitic CM-A) constituents. In the studied range of Ti/N ratios, the statistical analysis of precipitates revealed that Ti/N ratio has little influence on the average precipitation size, which was controlled in a tight range (52-57 nm). However, at near-stoichiometric Ti/N ratio, higher number density of precipitates in the simulated CGHAZ certainly contributed to the finer austenite grain size and hence improved CGHAZ toughness performance. (C) 2015 Elsevier Ltd. All rights reserved.