热输入对X100管线钢焊接热影响区组织和性能的影响

Effect of Heat Input on Microstructure and Impact Property of Heat Affected Zone for X100 Pipeline Steel

采用焊接热模拟技术、显微金相组织分析技术和冲击试验,研究了不同焊接热输入下X100管线钢热影响区组织和力学性能的变化规律。研究结果表明：当热输入E〉45 kJ/cm时,组织以粒状贝氏体为主,M-A组元为不规则大块状且带有尖角,降低了材料的韧性;当热输入E=15～35 kJ/cm时,组织主要为板条贝氏体和少量针状铁素体,M-A组元呈细小颗粒分布在铁素体基体上,尺寸较小,表现出对韧性有利的一面,冲击吸收功最高;当热输入E〈15 kJ/cm,组织中出现马氏体,导致材料的韧性下降,硬度最大。

The effects of different welding heat input on microstructure and mechanical properties of heat affected zone in X100 pipeline steel was studied by means of welding thermal simulation technology, mi- crostructure analysis and impact test. The results showed that when the heat input is greater than 45 k J/ cm, the microstructure is mainly composed of granular bainite, and M/A island is irregular large block with sharp comers, leading to the decrease of material toughness; when the heat input is 15 ~ 35 kJ/cm, the microstructures is mainly composed of lath bainite and a small amount of acicular ferrite, with fine M/ A island distributed in the ferrite matrix, which does not deteriorate on the toughness, and the resulted impact absorbed energy is at the highest value. When the heat input is less than 15 kJ/cm, martensite ap- pears in microstructure, the hardness of HAZ is the highest but the toughness decreases.