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通过研究焊接热影响区(HAZ)冲击功分布图,提出大热输入焊接用钢焊接粗晶热影响区(CGHAZ)韧性提升的新方法,即在峰值温度不变的条件下,将焊接CGHAZ中晶界铁素体(GBF)和大量针状铁素体(AF)组织改变成细晶热影响区(FGHAZ)多边形铁素体(PF)组织,并消除CGHAZ中破坏韧性的侧板条铁素体(FSP)组织。以对比Ti-V-N与Al-Ti-V-N微合金焊接用钢焊接CGHAZ组织和韧性为基础,探讨了Al-Ti-V-N钢焊接CGHAZ中PF转变条件、形核机制,认为微米级氧化夹杂物是诱导焊接CGHAZ中大量PF形核的关键,纳米级碳氮化物是拖曳、钉扎奥氏体与铁素体晶界的关键,两者的有效配合保证了焊接CGHAZ中大量PF组织生成,从而大幅提升焊接CGHAZ的低温冲击韧性。
By studying the impact energy distribution of the heat affected zone (HAZ), a new method of improving the toughness of the CGHAZ for the heat input welding steel is proposed. That is, under the condition of constant peak temperature, the CGHAZ (GBF) and a large amount of acicular ferrite (AF) were changed into the FGHAZ polygonal ferrite (PF) microstructure, and the destructive toughness of CGHAZ was eliminated Body (FSP) tissue. Based on the comparison of microstructure and toughness of CGHAZ for welding of Ti-VN and Al-Ti-VN microalloyed steels, the transformation conditions and nucleation mechanism of PF in CGHAZ of Al-Ti-VN steel were discussed. It is considered that micron-sized oxidized inclusions are The key to inducing a large number of PF nuclei in CGHAZ welding is nano-scale carbonitride, which is the key to dragging and pinning austenite and ferrite grain boundaries. The effective cooperation of the two ensures the formation of a large number of PF tissues in the welding CGHAZ, Improve the low temperature impact toughness of welding CGHAZ.