Dalong Cong

Thermal fatigue resistance of H13 die steel repaired by partial laser surface remelting process

Abstract In order to study the thermal fatigue resistance of H13 die steel repaired by a partial laser surface remelting process, a strengthening latticed morphology was designed and processed using a pulsed Nd:YAG laser by imitating the structures of certain animals and plants. The ultrafine microstructure within the strengthening unit is composed of martensite, austenite and finer carbides. The average microhardness of the unit is much higher than that of the original surface, even after thermal fatigue cycles. The results show that both percentage increase in crack length and crack density are reduced owing to the blocking effect of strengthening units. Partial laser surface remelting with the smallest spacing is the most effective for repairing cracks and improving the overall thermal fatigue resistance. A manufacturing verification test demonstrates the effectiveness of the partial laser remelting process in repairing thermal fatigue cracks of a casting die and improving its thermal fatigue resistance.