无缝钢管-精密钢管 的几种交货状态（BK,BKW,BKS,GBK,NBK）
上经常有人问，BK，BKW，BKS，GBK，NBK 是什么意思，我想看了这个大家应该明白了。
Designation | Symbol | Description |
交货状态 | 代号 | 说明 |
Cold finished (hard) | BK（+C） | Tubes do not undergo heat treatment following the final cold forming and, thus, have a rather high resistance to deformation |
冷加工(硬) | 最后冷加工之后不进行热处理, 从而管子只可能进行很小的变形. | |
Cold finished (Soft) | BKW（+LC） | The final heat treatment is followed by cold drawing involving limited deformation. Appropriate further processing allows a certain degree of cold forming (e.g. bending, expanding) |
冷加工(软) | 最后热处理之后进行小变形量的冷加工, 对钢管再加工时允许有限的冷变形(例如: 弯曲, 扩口) | |
Cold finished and stress-relieved | BKS（+SR） | Heat treatment is applied following the last cold forming process. Subject to appropriate processing conditions, the increase in the residual stresses involved enables both forming and machining to a certain degree. |
冷加工后消除应力退火 | 最后冷加工后在Acl点以下进行退火, 以消除冷加工应力. | |
Annealed | GBK（+A） | The last Cold forming process is followed by annealing in a controlled atmosphere. |
退火 | 最后冷加工之后,钢管在保护气体下进行完全退火. | |
Normalized | NBK（+N） | The last cold forming process is followed by annealing above the upper transformation point in a controlled atmosphere. |
正火 | 最后冷加工之后,钢管在保护气体下进行正火. |
