超低碳贝氏体钢焊接热影响区研究
A Study on HAZ of Ultra-low Carbon Bainitic Steel
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摘要: 用Gleeble-1500热模拟机研究了超低碳贝氏体(ULCB)钢,在不同焊接模拟热循环条件下HAZ的组织与性能。结果表明,适量铌,硼合金化的ULCB钢在不同焊接条件下都能获得具有良好冲击韧性的贝氏体组织。但焊接工艺的不同也直接造成焊后组织的差异而使低温断裂行为有所不同。采用径迹显微照相技术(PTA)研究了硼在钢中的偏聚行为,进一步探讨了不同t8/5时间对贝氏体组织形态的影响以及不同组织对低温裂纹扩展产生的不同作用。Abstract: Microstructure and properties of HAZ in an Ultr-low Carbon Bainitic(ULCB) steel were investigated by welding simulation on a Gleeble-1500 thermal simulator.Results indicated that the bainitic structure of excellent toughness can be obtained under different welding conditions in the HAZ of Nb and B microalloyed steel.It was also found that the fracture behaviour at low temperatures is defferent due to the microstructural disparity derived from the different welding condition.By analyzing the behaviour of boron segregation,further discussion about the effect of t8/5 on microstructural morphology and the effect of microstructure on crack propagation is also given.
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