锆加入量对船板钢焊接CGHAZ低温韧性及夹杂物形态影响

Effects of Zirconium on Impact Toughness of CGHAZ and Inclusion Morphology of Hull Structure Steel Plate during the Large Heat Input Welding

以加入微量锆船板钢为研究对象,采用Gleeble3500并结合SEM,TEM等实验方法研究了微量锆元素对F40船板钢大热输入焊接热循环粗晶热影响区(CGHAZ)低温韧性、夹杂物形态的影响。结果表明:与未添加锆元素船板钢相比,添加0.01%锆,钢中形成大量2～3 um尺寸范围、椭球状复合粒子,经150 kJ/cm大热输入焊接后,–60℃下CGHAZ冲击功高达224 J,材料的焊接性能大大提高;锆含量为0.02%时,钢中含锆夹杂物呈大尺寸矩形状,经150kJ/cm大热输入焊接后,–60℃下CGHAZ冲击功只有38 J,大尺寸矩形夹杂物是焊后低温韧性急剧下降的主要原因,分析表明含锆夹杂物形态受锆元素的添加量、错配度、ZrO2粒子界面能因素影响。

The Gleeble3500 combined with SEM,TEM and other experimental methods were employed to investigate the effects of zirconium content on impact toughness of coarse grain heat affected zone(CGHAZ) and the inclusion morphology of F40 hull structure steel plate during the large heat input welding.The results show that a large number of ellipsoidal complex inclusions in the range of 2～4 μm found in CGHAZ when 0.01% zirconium is added in the steel,the impact energy reaches 224 J at –60 ℃ experiencing 150 kJ/cm welding heat input.But the large-size rectangular inclusions are found in CGHAZ when 0.02% zirconium were added in the steel,the impact energy falls to 38 J at –60 ℃ experiencing 150 kJ/cm welding heat input.The large-size inclusions,especially rectangular inclusion,are the main cause for the sharp decline of low temperature toughness after welding.Further analysis shows that the morphology of zirconium-containing inclusion is affected by the amount of zirconium addition,the misfit and ZrO2 particle interfacial energy.