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利用ASPEX扫描电镜(SEM+EDS)对某厂两种钙处理工艺(工艺A:LF→钙处理→RH,工艺B:LF→RH→钙处理)生产X70管线钢冶炼和浇铸过程中的夹杂物进行系统的研究。结果表明:工艺A生产的X70管线钢板中夹杂物是CA6和CA2(C代表CaO,A代表Al2O3)为主的高熔点的钙铝酸盐。产生此类夹杂物的主要原因是RH真空精炼中钙的严重损失以及中间包的二次氧化。CA6和CA2等夹杂物极易聚集成大尺寸夹杂物,经过轧制后严重影响钢板性能,甚至导致钢板探伤不合格。工艺B生产的X70管线钢中夹杂物为CaO-Al2O3(少量)-CaS系夹杂物,这种夹杂物尺寸小,弥散分布,对轧板性能危害小。
The inclusions in the X70 pipeline steel smelting and casting process were produced by ASPEX SEM (SEM + EDS) on two kinds of calcium treatment processes (A: LF → Ca → RH → B: LF → RH → Ca) Conduct systematic research. The results show that inclusions in X70 pipeline steel produced by process A are high melting point calcium aluminate mainly composed of CA6 and CA2 (C represents CaO and A represents Al2O3). The main reason for producing such inclusions is the severe loss of calcium in the RH vacuum refining and the secondary oxidation of the tundish. CA6 and CA2 inclusions easily gathered into large-size inclusions, after rolling a serious impact on the performance of steel, and even lead to unqualified steel flaw detection. X70 pipeline steel produced by process B is CaO-Al2O3 (small amount)-CaS inclusions. The inclusions are small in size and diffusely distributed, and thus have little impact on the performance of the rolled sheet.