含Ti微合金钢中的第二相粒子对焊接粗晶热影响区组织及韧性的影响

利用碳萃取复型技术研究了含Ti微合金钢及其模拟粗晶区 (CGHAZ)中的第二相粒子 ,并利用OM(光镜 )、TEM(透射电镜 )及系列冲击试验对含Ti微合金钢及一种成分相近的不含Ti低合金高强钢焊接粗晶区的组织及韧性进行了研究。研究结果表明 ,含Ti微合金钢中含有大量的、尺寸细小的TiN粒子 ,这些粒子非常稳定 ,在焊接热循环过程中能有效地阻止奥氏体晶粒长大 ,抑制粗大贝氏体的形成 ,促进针状铁素体析出及M -A组元的分解 ,从而显著改善低合金高强钢焊接粗晶热影响区的韧性 ,t8/5(80 0～5 0 0℃冷却时间 )越大 ,这种改善作用越明显

Effect of Second Phase Partlde on Mlcrostructure and Toughness of CGHAZ in HSLA

Carbon extraction replica analysis was employed to measure the quantities and size distributions of particles in Ti microalboyed steel and its simu]ated CGHAZ to reveal the response behavior of second phase particle to the welding thermal cycle. And the microstmcture and impact toughness of CGHAZs in Ti microalloyed steel and a kind of HSLA steel with similar chemical content and manufacture process were investigated with OM , TEM and series charpy impact test. The results show that a large amount of small-size TiN particles exist in the Ti microalboyed steel. During the weld thermal cycling, TiN particles prohibit the original austenite grain from coarsening, prevent the formation of coarse upper bainite , accelerate the formation of acicular ferrite, and promote the decomposition of M-A constituent into ferrite and cementite, thus improve the toughness of CGHAZ in HSI.A steel remarkably. With the t515 increasing from 16s to 120 a, the toughness of CGHAZ in Ti microalloyed steel increased because the secondary microstructure of CGHAZ changes from upper bainite to acicular ferrite and the austenite grain size coarsening is not serious.ated CGHAZ to reveal the response behavior of second phase particle to the welding thermal cycle. And the microstmcture and impact toughness of CGHAZs in Ti microalloyed steel and a kind of HSLA steel with similar chemical content and manufacture process were investigated with OM , TEM and series charpy impact test. The results show that a large amount of small-size TiN particles exist in the Ti microalboyed steel. During the weld thermal cycling, TiN particles prohibit the original austenite grain from coarsening, prevent the formation of coarse upper bainite , accelerate the formation of acicular ferrite, and promote the decomposition of M-A constituent into ferrite and cementite, thus improve the toughness of CGHAZ in HSI.A steel remarkably. With the t515 increasing from 16s to 120 a, the toughness of CGHAZ in Ti microalloyed steel increased because the secondary microstructure of CGHAZ changes from upper bainite to acicular ferrite and the austenite grain size coarsening is not serious.