Causes Analysis on Surface Defects of HRB400 Rebars

A large number of scar and similar ‘crack’ defects were found on surface of HRB400 rebar, and the causes of the surface defects were analyzed by means of macroscopic analysis, chemical compositions analysis, metallographic examination and energy spectrum analysis. The results show that the surface defects of HRB400 rebar were fold and scar which caused by improper rolling. In addition, too high final rolling temperature and fast cooling rate resulted in formation of bainite at surface layer of the rebar, and this was also not allowed during the rebar production.