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S. Sobula, E. Olejnik and T. Tokarski

Abstract

Wear resistance of TiC-cast steel metal matrix composite has been investigated. Composites were obtained with SHSB method known as SHS synthesis during casting. It has been shown the differences in wear between composite and base cast steel. The Miller slurry machine test were used to determine wear loss of the specimens. The slurry was composed of SiC and water. The worn surface of specimens after test, were studied by SEM. Experimental observation has shown that surface of composite zone is not homogenous and consist the matrix lakes. Microscopic observations revealed the long grooves with SiC particles indented in the base alloy area, and spalling pits in the composite area. Due to the presence of TiC carbides on composite layer, specimens with TiC reinforced cast steel exhibited higher abrasion resistance. The wear of TiC reinforced cast steel mechanism was initially by wearing of soft matrix and in second stage by polishing and spalling of TiC. Summary weight loss after 16hr test was 0,14÷0,23 g for composite specimens and 0,90 g for base steel.

Open access

S. Sobula, A. Kwiecień, E. Olejnik and P. Pałka

Abstract

In this study, low-carbon cast steel was reinforced with TiC by SHS-B method, also known as combustion synthesis during casting method. The composite zone was then subjected to surface remelting by Gas Tungsten Arc Welding (GTAW) method. The remelting operation was realized manually, at 150 A current magnitude. Microstructure, phase composition and hardness of remelted zone were investigated. XRD results reveal that the phases of the composite zone in initial state consist of TiC and Feα. Surface remelting resulted in formation of thick layers containing TiC carbides, Feα and Feγ. Microstructural examination has shown strong refinement of titanium carbides in remelted zone and complete dissolution of primary titanium carbides synthetized during casting. The average diameter of carbides was below 2 μm. The structural changes are induced by fast cooling which affects crystallization rate. The hardness (HV30) of the remelted layer was in the range between 250 HV and 425 HV, and was lower than hardness in initial state.

Open access

J. Głownia, D. Koshal, R. Skoczylas and S. Sobula

Abstract

To obtain a right casting methoding of a yoke used in mining industry, a computer simulation of filling of mould cavity as well as casting solidification has been applied. Analysis of the casting solidification showed, that an initial casting methoding, based on common foundry practice, had to be changed. An initial bottom gating system was changed into a side-bottom one, what allowed smooth filling of mould cavity. Modified risering system enabled proper feeding of the casting. Ensuring high quality casting enable to substitute parts manufactured by forging

Open access

W. Stachurski, J. Łukasik, G. Kwinta, S. Sobula and Sz. Ostafin

Abstract

In this study a new concept of the cover for installation for continuous casting of steel have been studied and discussed. The main essence in the most favourable construction includes the existing stresses and strains developed in service conditions. Instead of former cover, made with heat-resistant concrete and flat plate, the new solution introduced two factors: increased rigidity whole cover and new thermal insulation material. It is a composite refractory material, more light, plastic and more resistant for thermal shocks. In the final results, the new tundish cover confirmed in practice prolongation of the cover exploitation from 15-25 000 tones to above 90 000 tones poured steel.

Open access

E. Olejnik, S. Sobula, T. Tokarski and G. Sikora

Abstract

Application of in-situ technique allows for fabrication of composite zone in the casting with a matrix of cast steel with low carbon content. The reinforcing phase in the composite zone is titanium carbide, produced by the synthesis of substrates introduced into the mould in the form of pressed compacts. Metallographic studies were performed in order to determine of homogeneity of composite zones and characteristic features existed in transition area between the composite zone and core of the casting. The transition areas of composites zone were blurred and there were no discontinuities caused by poor bonding between the composite zone and the core of the casting. To confirm the correct run of the TiC synthesis, phase analysis was performed of the base alloy as well as composite zone. The results of this examination indicated that there were two phases in composite zone, i.e. α Fe and TiC and only α Fe was observed in base alloy. Changes of mechanical properties in the composite zone were examined, measuring its hardness HV. The average hardness values of the base alloy and composite zone were 175 ±4 and 696 ±201 HV, respectively.

Open access

B. Kalandyk, G. Tęcza, R. Zapała and S. Sobula

Abstract

The results of the modification of austenitic matrix in cast high-manganese steel containing 11÷19% Mn with additions of Cr, Ni and Ti were discussed. The introduction of carbide-forming alloying elements to this cast steel leads to the formation in matrix of stable complex carbide phases, which effectively increase the abrasive wear resistance in a mixture of SiC and water. The starting material used in tests was a cast Hadfield steel containing 11% Mn and 1.34% C. The results presented in the article show significant improvement in abrasive wear resistance and hardness owing to the structure modification with additions of Cr and Ti.