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利用Gleeble热模拟技术,保持第一道次焊接热循环参数(模拟第一道次焊接粗晶区组织)不变,并将第二道次峰值温度固定为800℃,研究了第二道次焊接热循环不同冷却速度(2.0、6.8和15.3℃/s)对X100管线钢临界再热粗晶区组织及冲击性能的影响。结果表明:冷速为6.8℃/s时的冲击性能最高,冲击吸收能量平均为84.9 J,而2.0℃/s和15.3℃/s冷速下冲击吸收能量较低,分别为40.3 J和65.8 J。微观组织分析表明,不同冷速下晶粒内部组织均为板条状贝氏体和粒状贝氏体,但是沿原奥氏体晶界分布的马氏体-奥氏体(M-A)组元的体积分数和分布状态有较大差别。冷速为15.3℃/s时,M-A组元沿晶界成链状连续分布,且体积分数较高(6.3%)。而2.0℃/s和6.8℃/s下形成的M-A组元的体积分数相近,分别为3.3%和3.7%,但2.0℃/s时形成的组织中存在较多大尺寸、尖角形的M-A组元,对韧性的危害更大。
Using the Gleeble thermal simulation technique, the first pass welding thermal cycle parameters (simulating the first pass welding coarse grain zone) were kept unchanged and the second pass peak temperature was fixed at 800 ℃. The second pass welding Effect of Different Cooling Rates (2.0, 6.8 and 15.3 ℃ / s) on Microstructures and Impact Properties of Critical Reheat Crude Crystals in X100 Line Steel. The results show that the impact energy is the highest when the cooling rate is 6.8 ℃ / s, the average energy of impact absorption is 84.9 J, while the impact absorption energy is lower at cooling rates of 2.0 ℃ / s and 15.3 ℃ / s, which are 40.3 J and 65.8 J . The microstructure analysis shows that the internal structure of the grains is lath-shaped bainite and granular bainite at different cooling rates, but the martensite-austenite (MA) component distributed along the original austenite grain boundaries There is a big difference between the volume fraction and the distribution status. When the cooling rate is 15.3 ℃ / s, the M-A elements are continuously distributed in a chain along the grain boundaries, and the volume fraction is high (6.3%). However, the volume fraction of MA components formed at 2.0 ℃ / s and 6.8 ℃ / s are 3.3% and 3.7% respectively, but there are more large size and sharp MA components in the microstructure formed at 2.0 ℃ / s , More damaging to the toughness.