镁处理船板钢中IAF的诱发行为研究

Study on IAF induced by inclusions in magnesium-treated shipbuilding steel

镁处理可有效细化钢中夹杂物,并通过诱发IAF的形式提高船板钢的大线能量焊接性,但焊接热循环中温度对IAF诱发的影响尚不明晰。本研究先后对镁处理船板钢中夹杂物的尺寸、数量、组成进行了统计和分析,对其铸坯和轧材分别进行了不同温度的高温处理和相应的金相组织分析,并对诱发IAF的夹杂物构成进行了大量的分析。结果表明:镁处理后船板钢中夹杂物种类大幅增加,且尺寸在0.5~3μm的夹杂物数量占比达77.6%。对于试验钢而言,当加热温度超过其奥氏体化温度时,钢中的微细粒子能够有效地细化钢组织。对于IAF的诱发而言,轧材需要升温至1100℃以上,铸坯需要升温至1200℃以上。扫描电镜分析结果表明,能够诱发IAF的典型夹杂物为含MgO-Al_(2)O_(3)-Ti_(2)O_(3)的复合夹杂物。

With Mg treated,the inclusions in steel could be refined,and the high heat input welding performance of shipbuilding steel could also be improved by IAF inducing effectively,but the effect of temperature on the induction of IAF in welding process is still not clear.In this paper,the size,amount and composition of the inclusion have been counted and analyzed,the heat treatments of strand and plate have been carried out at different temperatures,the microstructures of the corresponding samples have been analyzed,and the inclusions which inducing IAF have also been analyzed.The results show that,the type of inclusions in shipbuilding steel increases greatly by Mg treatment,and the number of inclusions with a size range of 0.5-3μm accounts for 77.6%.For test steel,when the heating temperature exceeded the austenitizing temperature of the steel,the microstructure can be refined by the fine particles in steel effectively.For IAF inducing,the heating temperatures of strand should be higher than 1200℃,and for plate,it should be higher than 1100℃.The results of SEM show that,the typical inclusions which could induce IAF are mainly the MgO-Al_(2)O_(3)-Ti_(2)O_(3)-MnS composite inclusions.