Reaserch On Technics And Performance Of Aluminizing On Die Steel

H13 is one of internationally widespread used hot working die steels, mainly uses in making each kind of forging die,the hot extrusion mold,as well as copper aluminum and alloy hot extrusion mold and so on. When worked with the big impact load, the intense friction, fierce heating and cooling cycle alternately which caused the thermal load, often appears cracks, the collapse, wears, failure modes . Therefore, it has vital practical significance to use the suitable superficial modified technology to strengthen the high temperature wearability performance and the hot weary performance of the H13 steel. This article took the H13 hot work molding tool steel as the object of study, used the powder aluminizing technology to obtain Fe-Al alloy layer which has the outstanding performance in the surface, simultaneously, used the CeO₂ mix powder carrying on aluminizing to improve the level quality ofinfiltrates.By experimenting with conditions of process, the results showed that the optimum conditions for alnuminizing as follow: alnuminizing temperature at 950℃,aluminizing for 5h,NH4Cl charge of 1%.Under the best craft,infiltrates quality was continuously,thickness of aluminized layer may reach 90μm,it had a continuous layer between diffusion layer and matrix . The outer layer was mainly composed of Fe₃Al,FeAl ,the inner layer is composed of FeAl. Adding CeO₂ alnuminizing experiment results showed that: the best content of CeO₂ is 7%.At this time,thickness of aluminized layer may reach 220μm. The outer layer was mainly composed of Fe₃Al, FeAl, Al₃Cl; the inner layer is composed of Fe₃Al ,FeAl. Compared with the substrate of H13,the microhardness of the alloy layer are remarkably improved. It was pointed out that Fe3Al and FeAl plays an important role in hardness enhancement The Fe3Al and FeAl intermetallics which have higher strength and hardness at elevated temperatures. For specimen with rare earth , microhardness elevated also lied in the function which the rare earth the fine crystal strengthens. At the room temperature, the specimen which contains 0.7% wear weight loss is approximately 1/10 to aluminized solely specimen, is 1/40 to H13 the substrate, the wear-resisting performance obviously enhanced. at elevated temperatures (300-500℃), the anti-high temperature wearability surpassed the substrate obviously. When temperature increased, the anti-high temperature attrition performance is weaken.The result of thermal fatigue experiment shows that: after thermal cycles, the surface of H13 substrate developd a fine network of cracks , aluminized specimen surface to present the few short cracks hot fatigue resistance of aluminized sample increased greatly, but the aluminized specimen of adding the rare earth was more outstanding.