日本机械结构用碳素钢管 STKM11A STKM12A STKM12B STKM12C STKM13A STKM13B STKM13C STKM14A STKM14B STKM14C STKM15A STKM15C STKM16C STKM17A STKM17C STKM18A STKM18B STKM18B STKM18C STKM19A STKM19C STKM20A韩国机械结构用合金钢管 SCR420TK SCM415TK SCM418TK SCM420TK SCM430TK SCM435TK SCM440TK 韩国保证淬透性结构钢 SCR415H SCR420H SCR430H SCR435H SCR440H SN***15H SNC631H SNC815H SNCM220H SNCM420H SCM415H SCM418H SCM420H SCM435H SCM440H SCM445 SCM822H ***N420H ***JN433H ***N433H ***N438H ***N443H ***N***20H ***N***43H韩国保证淬透性结构钢旧钢号 SCR21H SCR22H SCR2H SCR3H SCR4H SNC21H SNC2H SNC22H SNCM21H SNCM23H SCM21H SCM22H SCM3H SCM4H SCM5H SCM24H ***N21H ***N1H ***N2H ***N3H ***NC21H ***NC3H