摘要
对A类夹杂物超标（A_细〉3.0级,A_粗〉2.5级）含硫齿轮钢QT20CrMo（/%：0.20C,0.020S,0.020Al,0.95Cr,0.20Mo）Φ16 mm轧材和150 mm×150 mm铸坯中的MnS央杂进行了分析,得出铸坯中心区域的大尺寸MnS夹杂物是轧材中超标A类夹杂物的来源,并且中心偏析严重是铸坯中心区域形成大尺寸MnS夹杂物的主要原因。通过将二次冷却比水量从0.37 L/kg提高到0.59 L/kg后,铸坯中心碳偏析指数由1.12～1.44降低至0.99～1.23,硫偏析指数由1.28～1.70降低至1.01～1.31,最大网状MnS尺寸由2 000μm降低至1 000μm。QT20CrMo钢轧材A类夹杂物合格率达100%,A细类央杂物≤2.0级的比例由25.0%提高至97.0%。
Based on analysis on MnS in Φ16 mm rolled products and in 150 mm× 150 nan casting billet of sulfur-bear- ing gear steel QT20CrMo （/% ：0. 20C,0. 020S,0. 020Al,0. 95Cr,0. 20Mo） to get the factors to occur non-qualified rating of A-type inclusions （Afine〉3 rating and Acoarse〉2.5 rating） in steel, it is obtained that the large size MnS inclusions occur- ring in central zone of casting billet are source of non-qualified rating A-type inclusions in roiled products and the serious center segregation is main reason of formed large size MnS inclusions in central zone of casting billet. With increasing sec- ondary cooling water rate from 0. 37 L/kg to 0. 59 L/kg, the billet central carbon segregation index decreases from 1.12 - 1.44 to 0. 93 - 1. 23, the sulfur segregation index decreases from 1.28 - 1.70 to 1.01 - 1.31 and the size of max network MnS decreases from 2 000μm to 1 000 μm. As a result the qualified rate of rating of A-type inclusions in steel QT20CrMo rolled products is up to 100%, and the ratio of ≤2. 0 rating of A-type thin inclusions increases from 25.0% to 97.0%.
出处
《特殊钢》
北大核心
2016年第6期27-31,共5页
Special Steel
