The break marks is a kind of strip marks that is vertical to rolling direction, occurring at some locations of hot-rolled steel strip during uncoiling.

Based on spike height resulting in break marks,the new technique of eliminating break marks by getting microstructure of quasi-acicular ferrite in hot strip mill was applied.

By analyzing the loading of strip at S rolls and formation mechanism and influencing factors of cross breaks,it was concluded that the main cause of cross breaks is the yield point elongation and the high tensile stress at the entrance of temper rolling mill.

By analyzing the technics of cold strip temper rolling and the working principles of temper rolling machine,it finded out the main cause of cross breaks is the yield point elongation and the high tensile stress at the entrance of temper rolling mill.

Automatic inspection of oil well tubing transverse defects and longitudinal defects is a key means to guarantee the quality of repaired oil well tubing and reduce accidents in oil extraction.

The influence of over-heat and draw speed on inner fold defects of seamless steel tube is analyzed in hot test process of 20 steel from point of view of inner solidified organization of CC billet.