合金结构钢SCr415SCr420SCr430SCr435SCr440SCr445SNC236SN***15SNC631SNC815SNC836SNCM220SNCM240SNCM415SNCM420SNCM431SNCM439SNCM447SNCM616SNCM625SNCM630SNCM815SCM415SCM418SCM420SCM421SCM430SCM432SCM435SCM440SCM445SCM822***n420***n433***n438***n443***n***20***n***20***nC443)