Optimizing the Morphology of Primary Carbides and Mechanical Properties during Processing Of Cast-Steel (Din Gx210crv12 1) Press-Forming Dies

Abstract

Elghazaly SA, Gyula K, Elghazaly W and K Elbarghuti

Cold work tool steels are used for punching, cutting, forming, cold forging, cold extrusion, cold rolling…etc. Those steels have hard microstructure compared to most other steels, but the everlasting challenge is the enough strength to toughness relation, without immediate fracture. Carbides provide the wear resistance, acting as the hard phase of the material. Variation in size and fraction of the carbides, depending of manufacturing route, alloy content, hot working/forging and heat treatment, will give the tool steel the desired mechanical properties. However, conventional cast-tooling is the major production route used, which could be followed by a process called electro slag refining/ re-melting (ESR) where the non-metallic inclusion content is lowered. Conventional casting has a lower production cost per unit than the conventional processing routes. The disadvantage though is a more heterogeneous material, due to segregation of primary or leduburitic carbide net cells. In this investigation a trial was made to control the distribution and morphology of primary carbides in the matrices of marten site by spheroidizing them through molten metal treatment or heat treatment processes. Types and distributions of different carbides in the matrix was measured using X-ray diffraction and SEM/EDX units. Industrial performance has been recorded for the optimized pressing dies as compared with the same imported dies created through the conventional forged or rolled-machined ones. Hardness and fracture toughness were measured for both experimental specimens and the actual working die.

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