Cast steel-SiC composites as wear resistant materials

Abstract

In the present paper the possibilities of making and applying of cast-incarbide composites based on carbon steel and SiC, for the production of wear resistance machine parts such as mill hammers, escavator teets, etc. are studied. Materials usually used for the making of these wear resistant parts, the high-alloyed Cr-Mo steels, have shown very good results in practice, and considerably better safety of work of different devices in which these materials have been built in. However, wear resistant parts used in mining, industry, civil engineering and traffics are in the exploitation exposed to the strong abrasive acting of the silica, corundum, feldspath and other minerals, and by this, strikes often occur in present stones and rocks. These strikes are especially dangerous because they can lead to breakdown of the construction part or complete device, since mentioned materials have relatively small impact toughness. The best variant of the construction is to make the wear resistant parts of the material which, besides hardness, possess high impact toughness, dynamic strength and fracture toughness. So far, used materials, mostly high-alloyed Cr-Mo steels, do not have this combination of the properties, and the aim of this research was to check the possibility of production and application of the new MMC materials based on steel matrix and SiC as reinforcement particles, which have just such characteristics. The optimized content and disposition of SiC particles in the steel combine extreme hardness and wear resistance of casting surface rich in SiC, with high strength and toughness of metal base.

U radu su razmatrane mogućnosti izrade i primene cast-in-carbide kompozita, čelik-SiC, za proizvodnju mašinskih delova otpornih na habanje kao što su: mlinski čekići, zubi bagera, itd. Materijali koji se uobičajeno koriste za izradu delova izloženih habanju, visokolegirani Cr-Mo čelici, pokazali su veoma dobre rezultate u eksploataciji i veoma dobru sigurnost u radu različitih uređaja u koje su takvi delovi bili ugrađeni. Međutim delovi izloženi habanju koji se koriste u rudarstvu, industriji, građevinarstvu i saobraćaju su u eksploataciji izloženi jakom abrazionom dejstvu kvarca, korunda, feldspata i drugih minerala, a često i udarima o prisutne stene i kamenje. Ovi udari su posebno opasni jer mogu da dovedu do loma konstrukcionih delova ili kompletnog uređaja, obzirom da navedeni materijali imaju relativno malu udarnu žilavost. Najbolja varijanta konstrukcije je da delovi budu napravljeni od materijala koji, pored tvrdoće poseduje visoku udarnu žilavost, dinamičku čvrstoću i žilavost loma. Obzirom da uobičajeno korišćeni materijali, uglavnom visokolegirani Cr-Mo čelici, ne poseduju ovakvu kombinaciju osobina, cilj istraživanja je bio da se ispitaju mogućnosti proizvodnje i primene novih kompozitnih materijala sa metalnom osnovom zasnovanih na čeliku kao osnovi i česticama SiC kao ojačivaču, koji poseduju upravo takve karakteristike. Optimalni sadržaj i raspored SiC čestica u čeliku, kombinuju visoku tvrdoću i otpornost na habanje površinskog sloja bogatog sa SiC sa dobrom žilavošću i čvrstoćom čelične metalne osnove.