Conical pick is a widely used tool for cutting coal in mines. It has a cemented carbide tip inserted in a steel body. Cemented carbide has been in use for many years for coal/rock cutting because it has the optimum combination of hardness, toughness and resistance against abrasive wear. As coal/rock is a heterogeneous substance, the cutting tool has to undergo various obstructions at the time of excavation that cause the tool to wear out. The cracks and fractures developing in the cemented carbide limit the life of the tool. For a long time, different wear mechanisms have been studied to develop improved grades of cemented carbide with high wear resistance properties. The research is still continuing. Moreover, due to the highly unpredictable nature of coal/rock, it is not easy to understand the wear mechanisms. In the present work, an attempt has been made to understand the wear mechanisms in four conical picks, which were used in a continuous miner machine for underground mining of coal. The wearing pattern of the conical pick indicates damage in its cemented carbide tip as well as the steel body. The worn out parts of the tools have been critically examined using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) point analysis. Mainly four types of wear mechanisms, namely, coal/rock intermixing, plastic deformation, rock channel formation and crushing and cracking, have been detected. The presence of coal/rock material and their respective concentrations in the selected area of worn out surface were observed using the spectra generated by EDX analysis.

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Purpose The purpose of this study is to critically analyze the properties of quenched and tempered steel samples. Austenite to martensite transformation of steel is a common process in any steel industry. Water quenching is the best suited technique to convert the steel into martensitic structure. Although quenched products are very hard, yet they possess brittleness. Due to which, their industrial applications become very limited. To avoid this problem, tempering of the martensite is usually done to achieve the required combination of hardness and toughness. Design/methodology/approach The present work deals with comparative analysis of mechanical properties and microstructural behavior of quenched and tempered steel samples. For the purpose, a low carbon steel (0.2%-C) was taken under study. Quenching was done in water, and tempering was done in atmospheric air. Four different mechanical properties such as tensile strength, toughness, hardness and shear strength were analyzed on steel samples that underwent through two different above-mentioned heat treatment processes. Findings An improvement in all the four mechanical properties was reported after tempering the quenched products. Also, the microstructural images of quenched and tempered specimens showed a good corroboration with mechanical properties. Originality/value A significant improvement in mechanical properties was reported in tempered specimens. Also, there was a strong corroboration between mechanical properties and microstructural attributes. A clear view of needle-shaped martensite and lamellar-shaped pearlite was observed in water-quenched and tempered specimens, respectively.

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