Z.J. Han
金属学报(英文版)
Calcium treatment is nowadays a well-established method to improve steel castability and final properties e.g. machinability, toughness and surface quality. The effects of calcium are mainly based on its strong ability to form sulphides and oxides. The topic of the present paper concerns the basic mechanism and kinetics of the transformation process of alumina inclusions in steel when calcium introduced into the steel e.g. by wire feeding or powder injection.
To clarify the mechanisms model experiments were performed by studying reactions between Al2O3 and CaO in a laboratory furnace as well as by performing Ca treatments in an 8 kg induction furnace for Al deoxidised melt. The phases formed during the reaction between Al2O3 and CaO were examined by SEM-EDS, and the proposed reaction sequence of Al2O3CA6CA2CACAx(liquid) was discussed based on the experimental observations. The kinetics of the reaction of calcium with alumina inclusions were simulated by immersing alumina plates in a Ca treated steel melt in the induction furnace. Results were compared with observations of real inclusion transformation. Based on the results a kinetic model was proposed.
关键词:
Alumina inclusions
,
夹杂
,
机理
,
钙处理
,
动力学
罗小兵
,
柴锋
,
苏航
,
杨才福
,
侯振伟
,
李超
钢铁研究学报
按照IMO(国际海事组织)规定的《油轮货油舱用耐蚀钢性能标准》模拟了货油舱上甲板的腐蚀环境,研究了两种船用低合金钢的腐蚀行为.结果表明,在含H2S干湿交替环境下,船体钢腐蚀类型为均匀腐蚀,传统E36船板的腐蚀速率超过0.4 mm/a；在钢中添加一定量的Cu、Ni,促进了锈层中稳定相α-FeOOH的形成,减少了锈层中裂纹等缺陷,锈层更加致密连续,提高了钢的耐蚀性；夹杂物改性处理在钢中获得5～10μm的球状CaO、CaS夹杂物,该夹杂物的溶解在基体表面生成碱性产物,提高了表面液膜的pH值,减缓了酸性环境下基体的腐蚀.
关键词:
货油舱
,
H2S
,
干湿交替
,
钙处理
王新华
,
李秀刚
,
李强
,
黄福祥
,
李海波
,
杨建
金属学报
doi:10.3724/SP.J.1037.2012.00505
采用转炉-钢包精炼炉-RH真空精炼-钙处理炼钢工艺生产的X80管线钢板中,条串状B类夹杂物主要为低熔点CaO-A12O3系,其成因主要为:(1)炉外精炼和钙处理后,钢液中存在许多微小CaO-Al2O3系液态夹杂物,连铸过程聚集成较大尺寸夹杂物(10-20 μm),轧制过程中变形为大型条串状夹杂物.(2)尺寸较大的夹杂物在钢液钙处理时,外表层转变为高熔点CaO,CaS或CaO-CaS系,但内部仍为低熔点的CaO-Al2O3系,此类夹杂物在钢板轧制时,内部仍能够变形,最终延展为条串状夹杂物.对X80管线钢板B类夹杂物的控制采用新的策略,将控制重点由钢液钙处理后去除低熔点CaO-Al2O3系夹杂物,改为在钙处理前强化去除钢液中夹杂物,尤其是较大尺寸的夹杂物.采取新控制策略后,真空精炼后夹杂物数量大幅度降低,钙处理效果显著提高,钢板中检测到的夹杂物全部为高熔点CaO-CaS系夹杂,B类夹杂物评级由以往低于2.0级降低至0级.
关键词:
X80管线钢
,
非金属夹杂物
,
B类夹杂物
,
二次精炼
,
钙处理
王慧华
,
徐英君
,
郝月莹
,
郭瑞琪
,
屈天鹏
,
王德永
钢铁研究学报
doi:10.13228/j.boyuan.issn1001-0963.20150107
以铝镇静钢为研究对象,在120t钢包内分别进行了镁处理和钙处理试验,对比了钢中夹杂物的成分、形貌、尺寸和分布.结果表明:镁处理试验炉次TO的去除率超过50％,钙处理炉次仅为30％,证明镁处理净化钢液效果更为明显;镁处理可将Al2O3迅速变质为尖晶石或MgO,夹杂物分布弥散,尺寸细小且基本不随时间延长而增大;钙处理对夹杂物的变质速度稍慢,夹杂物数量先增加后降低,尺寸降低不明显.界面理论计算表明,在同一体系内,将Al2O3变质为尖晶石比变质为铝酸钙具有更低的界面自由能,即镁处理可获得比钙处理更小的夹杂物尺寸,证明了精炼过程中夹杂物成分控制的重要性.
关键词:
夹杂物
,
镁处理
,
钙处理
,
界面理论
