16mn低合管機械性能指標如下（%）：牌號壁厚mm?伸長率δ5≥（%）屈服強度δs(MPa≥)?試驗溫度℃?抗拉強度σ(MPa≥)Q345A?≤16?????21???????????345???????????????不需???????470-630?Q345B? ≤16?????21???????????345????????????????20????????470-630?Q345C? 16-35????22???????????≥325??????????????0?????????470-630?Q345D? 35-50????22???????????≥295?????????????-40????????470-630?Q345D? 50-100???22???????????≥275?????????????-40????????470-630