Product Name

Executive Standard

Specification Range

Steel Grade

Seamless steel tube for elevated temperature

EN10305-1

OD4~76 x WT0.5-8

E215,E235,E355

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.

Cold finished (Soft)

BKW

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)

（+LC）

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.

Annealed

GBK（+A）

The last Cold forming process is followed by annealing in a controlled atmosphere.

Normalized

NBK（+N）

The last cold forming process is followed by annealing above the upper transformation point in a controlled atmosphere.