Thermal fatigue behaviour of Fe-1.7C-11.3Cr-1.9Ni-1.2Mo roller steel in temperature range 500-700 ℃

摘要

Thermal fatigue resistance of a high Cr hot work roller steel is evaluated at 500, 600 and 700 degrees C. Surface layer degradation was investigated and characterised after a finite number of thermal cycles. Degradation mechanisms of the cooled surface layer in relation to the size, shape, orientation, distribution of carbides and crack oxidation progress were elucidated. Complex phenomena of crack growth is discussed where internal cracks nucleate due to stress at crack tip and oxidation along carbides follows from crack tail. Quantitative evaluation of cracks shows increased crack length with increasing temperature and number of thermal cycles.