单项选择题
A.促进石墨化B.提高机械性能C.脱氧D.脱硫
A.1.31B.1.41C.1.51D.1.71
A.0.10%〜0.30%B.0.30%〜0.50%C.0.50%〜0.80%D.0.80%〜0.90%
A.0.1%-0.2%B.0.2%-0.45%C.0.45%-0.6%D.0.6%-0.8%
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