原材料硬度参考材料规格hrb马钢35kφ882-84马钢35kφ1484-87宝钢35k85-8740cr90-93直40cr94-97宝钢45#89-90宝钢18a70-71邢ml08ac51-53武swrm865-66太ml2071-75武22a72-76马8a58-62