2014 Volume 100 Issue 3 Pages 366-375
The electric process has the advantage such as the low amount of CO2 emission. But, the tramp elements such as Cu and Sn contained in steel are retained in the puddling process. These tramp elements cause surface cracking of steel during hot rolling process. The surface hot shortness is suppressed by addition of Ni. The scale/steel interface of Ni addition steel is rugged. The rugged scale/steel interface occludes segregated tramp elements into the scale. The authors have reported the influence of shot peening to suppress surface hot shortness.
The effect of shot peening was development of microscopically homogenous and microscopically heterogeneous oxidation due to the increase of defects such as dislocations and lattice distortions. The rugged scale/steel interface was produced by microscopically heterogeneous oxidation. The rugged scale/steel interface occluded the enriched Cu into the scale. The suppression of surface hot shortness like Ni addition was occurred by shot peening.
This paper describes the mechanism of shot peening on the suppression of surface hot shortness at the initial stage of oxidation. The grain refining is occurs by shot peening at the surface of steel. The refined grains have various crystal orientations which was observed by EBSP. The interior matrix grains have crystal orientation of 3-degree or more. And, the locally-diffused O signal which diffused along refined grain boundaries and dislocation were observed by EDX. The scale/steel interface is being rugged by the microscopically heterogeneous oxidation which was hastened by the locally-diffused O2– ion.
