CAJ | 학술논문

研究了一种低碳高强贝氏体钢焊接热影响区粗晶区在不同热输入条件下的组织与性能。结果表明,该钢热影响区粗晶区的低温冲击吸收功随t8/5的增加先增大后减小。当t8/5为30 s时,少量细小粒状贝氏体分割板条贝氏体,使板条贝氏体更细,方向性减弱,低温韧性最佳。当t8/5大于或小于30 s时,钢的组织形态发生变化,均使低温冲击韧性降低。随着冷却速度的降低及t8/5的增大,热影响区硬度呈逐渐减小的趋势;当t8/5超过30 s后,热影响区的硬度低于基材,此时热影响区粗晶区将发生软化。所以,对焊接热输入进行控制、减少热影响区软化是保证焊接接头强度的重要措施。
연구료일충저탄고강패씨체강한접열영향구조정구재불동열수입조건하적조직여성능。결과표명,해강열영향구조정구적저온충격흡수공수t8/5적증가선증대후감소。당t8/5위30 s시,소량세소립상패씨체분할판조패씨체,사판조패씨체경세,방향성감약,저온인성최가。당t8/5대우혹소우30 s시,강적조직형태발생변화,균사저온충격인성강저。수착냉각속도적강저급t8/5적증대,열영향구경도정축점감소적추세;당t8/5초과30 s후,열영향구적경도저우기재,차시열영향구조정구장발생연화。소이,대한접열수입진행공제、감소열영향구연화시보증한접접두강도적중요조시。
Microstructural evolution and mechanical properties of coarse-grained heat-affected zone（CGHAZ） in a kind of low carbon bainitic steel were investigated at different heat inputs by means of welding thermal simulation on an MMS-300 thermo-mechanical simulator.The results show that the impact toughness of CGHAZ is first increased and then decreased with increasing t8/5.When t8/5 is equal to 30 s,lath bainite can be split by a small amount of fine granular bainite such that lath bainite is finer and has weak directionality.In this case,the steel has the best low temperature impact toughness.The impact toughness is decreased when t8/5 is greater than or less than 30 s owing to the change of microstructure.With the decrease of cooling rate and the increase of t8/5,the hardness of heat-affected zone is gradually decreased.When t8/5 is greater than 30 s,the hardness of heat-affected zone is lower than that of base metal and the softening of CGHAZ will occur.Therefore,an important way to ensure the strength of welded joints is to control the heat input in order to reduce the softening of heat-affected zone.