| Hot working die is an important tool for material thermal forming in the processing ofindustrial production. Because of the harsh working environment, the service life of hotworking die is short, the damage ratio of die that caused by thermal fatigue failure is about ashigh as seventy percent. H13hot working die steel has been used as mold materialscommonly, also widely used in industry at home and abroad, therefore, improving thethermal fatigue performance of H13hot working die steel, can effectively extend the servicelife of hot working die, and is of great significance. Previous studies have showed that, on thebasis of the biomimetic coupling theory, the thermal fatigue property of the hot working diesteel which commonly used in the present research and production has been greatly improvedafter treated by laser biomimetic coupling technique. There are many biomimetic couplingelements that affect the thermal fatigue property of laser biomimetic coupling samples, suchas the shape coupling element, that is the shape and size of the units; and the structurecoupling element, namely the distribution and distance of the units; and the material couplingelement, refers to the chemical composition and microstructure of the units. Throughchanging the biomimetic coupling elements, the thermal fatigue properties of the biomimeticcoupling specimens can be further changed. The effect of the shape coupling element, thestructure coupling element and its characteristic quantity on the material thermal fatigueproperty of H13hot working die steel has been studied previously, so the effect of materialcoupling element on the thermal fatigue property of H13hot working die steel has beenmainly studied in this paper.In this paper, material coupling element has been enhanced through the laser cladding andthe pulse current processing technology. The chemical composition and the alloy phase of thebiomimetic coupling unit has been changed and strengthened by the laser cladding processing;besides, the microstructure of the material has been changed by the pulse current strengthening treatment, so that the unit and the matrix of the laser biomimetic couplingspecimens have been strengthened. The effect of different alloy powders on the changes ofthe microstructure and microhardness of the unit and the thermal fatigue property also hasbeen studied in this paper; and the effect of pulse current treatment on the changes ofmicrostructure and property of the unit and matrix and thermal fatigue property.The study has found that, compared with laser melting treatment, the composition of theunit has been greatly changed by the laser cladding treatment, and the fundamental propertyof material also has been improved effectively; after the thermal fatigue test, the ability ofresisted thermal cycle softening and thermal stability of the unit of laser cladding Co50alloypowder are superior to the unit of laser cladding Fe30A alloy powder, and both of them arebetter than the laser melting unit, and the growth of thermal fatigue cracks has been inhibitedeffectively. Therefore, the thermal fatigue properties of biomimetic coupling specimens havebeen further improved by the laser cladding processing. After the pulse current treatment, thestructures of the unit and the matrix have been refined, and some fine cryptocrystallinemartensites microstructure have been generated in the material matrix region, and themicrohardness and strength have been enhanced, and the material internal morphology hasbeen improved, and the initiation time of thermal fatigue crack also has been extendedeffectively, thereby, the thermal fatigue properties of biomimetic coupling specimens havebeen enhanced. |
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