Research On Preparation Of Cr12MoV/TiC Composite

Cr12MoV steel is a representative cold-work mold steel with high carbon and high chromium.The ingot obtained by melting and casting contains coarse carbides,which seriously shorts the mold life.In practice,the coarse carbides are broken by repeated upsetting and drawing to improve the morphology and distribution of carbides,but this improvement is limited,so that the properties of Cr12MoV steel are not effectively developed;The addition of RE and Ti in the smelting process can refine the ingot grain and improve the performance of Cr12MoV steel,but there are still serious carbide segregation in this steel.In order to solve the above problems,this paper analyzes the effect of Ti on the solidification process of Cr12MoV steel,and confirms that it is not suitable to add Ti to Cr12MoV by smelting method.Therefore,this paper try to prepare Cr12MoV/TiC composite materials by powder metallurgy method,that is,Cr12MoV/TiC composite materials are prepared by powder forging method with Cr12MoV powder and TiC powder as raw materials,effects of TiC content and forging force on the microstructure and properties of Cr12MoV/TiC composite were investigated.At the same time,Cr12MoV/TiC composite was prepared by cold pressing-sintering method,and the effects of TiC content and sintering temperature on the microstructure and properties of Cr12MoV/TiC composites were explored.The results show that TiC added in in the powder forging process is located on the boundary between Cr12MoV particles and tends to aggregate.There are a lot of oxides at the particle boundaries,resulting in poor performance of the sample.The highest relative density of forged samples is only 94.3%,which is far from the requirements of powder metallurgy compacts,but it is possible to improve.When Cr12MoV/TiC composite materials are prepared by cold pressing-sintering method,the density of samples increases gradually with the increase of sintering temperature.The suitable sintering temperature is around 1160?,it is necessary to appropriately increase the sintering temperature with the increase of TiC content.The hardness and impact toughness of the samples sintered at 1160?with 5%TiC addition are 52.7 HRC and 6 J·cm^-2respectively,which are also different from the properties of powder metallurgy compacts.Based on the comprehensive analysis of the experimental results of powder forging and cold pressing sintering,it is considered that although there are no dense P/M samples obtained by the two preparation methods,it is possible to prepare Cr12MoV/TiC composite materials with excellent performance by combining the two preparation methods of sintering and forging and proper optimization.