Luquan Ren

Properties of 3Cr2W8V Die Steel With Striations Processed by Laser

The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance and mechanism of thermal fatigue crack propagation in the zone processed by laser were observed and discussed. The results show that the wear resistance and thermal fatigue resistance of materials processed by laser are all better than those of the unprocessed material. The processed zone by laser plays a role in baffling wearing process and crack propagation. The pile-nail effect of processed zone is the main factor for improving the wear resistance and thermal fatigue resistance of material.

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.