精密鋼管常（cháng）用牌號（hào）化學成份

    標準 牌號（hào） 化學成份% 碳 矽 錳 硫 磷 鉻（gè） C Si Mn S P Cr GB/T699 GB/T3639-2000 GB3077-88 10# 0.07~0.13 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035                       20# 0.17~0.23 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035                                          35# 0.32~0.39 0.17~0.37 0.35~0.65 ≤0.035 ≤0.035                                          45# 0.42~0.50 0.17~0.37 0.50~0.80 ≤0.035 ≤0.035                                         40cr 0.37~0.44 0.17~0.37 0.50~0.80 ≤0.035 ≤0.035 0.08~1.10                             25Mn 0.22~0.2 0.17~0.37 0.70~1.00 ≤0.035 ≤0.035 ≤0.25                                 37Mn5 0.30~0.39 0.15~0.30 1.20~1.50 ≤0.015 ≤0.020