S355J2W(H)钢镁处理洁净度及生产问题解析  

Discussion on the cleanliness and production issues of S355J2W(H) steel by magnesium treatment

作　　者：高燕 张浩 付建勋 沈平 GAO Yan;ZHANG Hao;FU Jianxun;SHEN Ping(Nanjing Iron and Steel Co.,Ltd.,Nanjing 210035,China;Center for Advanced Solidification Technology(CAST),State Key Laboratory of Advanced Special Steel,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China)

机构地区：[1]南京钢铁股份有限公司,江苏南京210035 [2]上海大学材料科学与工程学院,先进凝固技术中心,省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444

出　　处：《冶金分析》2024年第1期26-34,共9页Metallurgical Analysis

基　　金：国家自然科学基金(52104334,51874195)。

摘　　要：某厂生产S355J2W(H)钢时,采用镁处理技术,夹杂物改质效果不稳定,产品质量和性能改善不明显。为此,本文对镁处理S355J2W(H)钢的过程样和铸坯样进行解析,采用光学显微镜、扫描电子显微镜(SEM)、夹杂物三维腐刻技术对钢中夹杂物的大小、形态、成分、分布等进行检测,确定铸坯不同部位的洁净度水平,通过热力学计算确定镁处理过程中夹杂物的转变规律及临界转变条件,确定问题产生原因。研究表明,夹杂物在铸坯不同部位中,内弧1/4处及铸坯中心部位夹杂物尺寸最大,面积占比也最大,符合一般夹杂物在铸坯中分布规律,但氧化物夹杂成分及类型存在多样性,在铸坯中同时包含CaO-Al_(2)O_(3)、CaO-MgO-Al_(2)O_(3)、MgO·Al_(2)O_(3)、MgO,夹杂物类型跨度较大,改质不均匀,钢中Mg含量偏低及分布不均匀是导致该问题的主要原因。The magnesium treatment technology was adopted for the production of S355J2W(H) steel in one factory.The modification effect of inclusions was not stable,and the improvement in product quality and performance was not obvious.Therefore,the process sample and casting slab sample in the magnesium treatment of S355J2W(H) steel were analyzed.The size,morphology,composition,and distribution of inclusions in steel were detected by optical microscope,scanning electron microscope(SEM) and three-dimensional etching technology for inclusions.The cleanliness level at different positions of casting slab were determined.The transition rule and critical transition condition of inclusions in the process of magnesium treatment were obtained by thermodynamic calculation.The causes for the problems were found out.The results showed that among different positions in the casting slab,the size of inclusions at 1/4 of inner arc and center of casting slab was maximum.Meanwhile,the area proportion was also maximum,which conformed to the distribution rule of general inclusions in the casting slab.However,the composition and type of oxide inclusions had diversity.The casting slab contained CaO-Al_(2)O_(3),CaO-MgO-Al_(2)O_(3),MgO·Al_(2)O_(3) and MgO simultaneously.The modification was uneven due to the various types of inclusions.Low content and nonuniform distribution of Mg in steel was the main reason to cause such issue.

关 键 词：S355J2W(H)钢 镁处理 夹杂物 洁净度 热力学计算 光学显微镜 扫描电子显微镜(SEM) 夹杂物三维腐刻技术 

分 类 号：TF76[冶金工程—钢铁冶金]