单项选择题
A.1006 B.ML40Cr C.C82DA D.55SiCr
A.SPA-H B.S355JR C.S420MC D.SG295
A.GCr15 B.30CrMo C.QStE420TM D.Q235B
A.30MnSi B.SWRH82B C.45 D.SWRCH35K
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