Li Yandong, Xing Weiwei, Li Xiaobing, Chen Bo, Ma Yingche, Liu Kui, Min Yi
Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology (EBEAM), Yangtze Normal University, Chongqing 408100, China.
Institute of Metal Research, Chinese Academy of Sciences, No.72 Wenhua Road, Shenyang 110016, China.
Materials (Basel). 2021 May 8;14(9):2445. doi: 10.3390/ma14092445.
To reveal the effect of Mg treatment on the microstructure evolution behavior in the actual steel welding process, the microstructure and properties of Al-deoxidized high-strength ship plate steel with Mg addition were analyzed after double-side submerged arc welding. It was found that the Al-Mg-O + MnS inclusion formed under 26 ppm Mg treatment could promote acicular ferrite (AF) nucleation in the coarse-grained heat-affected zone (CGHAZ) and inhibit the formation of widmanstätten ferrite and coarse grain boundary ferrite. In the fine-grained heat-affected zone (FGHAZ) and intercritical heat-affected zone (ICHAZ), polygonal ferrite and pearlite were dominant. Al-Mg-O+MnS cannot play a role in inducing AF, but the grain size of ferrite was refined by Mg addition. The impact toughness in HAZ of the Mg-added steel was higher than that of Mg-free steel. With the heat-input rising from 29.55 to 44.11 kJ/cm, it remained relatively stable in Mg-treated steel. From the fusion line to the base metal, the micro-hardness of the fusion zone, CGHAZ, ICHAZ and FGHAZ decreased to some extent after Mg addition, which means the cold cracking tendency in the welding weak zone could be reduced. Finally, the mechanisms of Mg-containing inclusion-induced AF were also systematically discussed.
为揭示镁处理对实际钢焊接过程中微观组织演变行为的影响，对添加镁的铝脱氧高强度船板钢进行双面埋弧焊后，分析了其微观组织和性能。研究发现，在26 ppm镁处理条件下形成的Al-Mg-O + MnS夹杂物可促进粗晶热影响区（CGHAZ）中针状铁素体（AF）形核，并抑制魏氏铁素体和粗大晶界铁素体的形成。在细晶热影响区（FGHAZ）和临界热影响区（ICHAZ）中，多边形铁素体和珠光体占主导地位。Al-Mg-O+MnS在诱导AF方面不起作用，但添加镁细化了铁素体晶粒尺寸。添加镁的钢热影响区的冲击韧性高于无镁钢。随着热输入从29.55 kJ/cm提高到44.11 kJ/cm，镁处理钢中的冲击韧性保持相对稳定。从熔合线到母材，添加镁后熔合区、CGHAZ、ICHAZ和FGHAZ的显微硬度均有一定程度降低，这意味着可降低焊接薄弱区的冷裂纹倾向。最后，还系统讨论了含镁夹杂物诱导AF的机制。
