The thermal fatigue resistance of H13 steel repaired by a biomimetic laser remelting process

In this study, the biomimetic laser remelting process was adopted to repair thermal fatigue cracks on an annealed hot work die AISI H13 steel. Several treated morphologies: spot, striation and lattice were processed by a pulsed Nd:YAG laser. The ultrafine microstructure within the unit was comprised of martensite, austenite and carbides. The average microhardness of the unit is much higher than that of the original surface, even after thermal cycles. Thermal fatigue results show that both crack density and crack length are reduced due to the blocking effect of strengthening units. And the partial laser surface remelting with lattice morphology is the most effective for repairing cracks and improving the thermal fatigue resistance of all.