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Pre-requisite of any agricultural implement is the desired combination of hardness and wear resistance properties. The implements conventionally manufactured from high carbon (similar to 0.70 C) steel is unsuitable for harsher applications (desert areas and harder soil condition) as after heat treatment it can produce hardness of HRC 38-45 only against a requirement of 50-60 HRC. Therefore, medium carbon (similar to 0.30C) steels with microalloy additions of boron/chromium are being selected to achieve higher hardness and better wear resistance in the steel. The increase in hardness is due to faster cooling rate (water quenching) and increased hardenability is attributed to microalloy additions of boron/chromium in the steel. Because of low cost of heat treatment, the demand of such grade exists in many advanced countries. So, it was felt necessary to characterize both the high carbon (similar to 0.70 C) and medium carbon (similar to 0.30C) low alloy steels for their possible application in agricultural implements such as tillage discs, soil and plant engaging components etc. The heat treatment parameters were optimized to achieve the desired mechanical properties, which largely depend upon its chemistry, quenching temperature and cooling rate.

Extensive wear tests were carried out to establish the grades for their end applications in specific soil conditions. The wear pattern, as measured from weight loss, clearly established the superior performance of boron/chromium steel. In fact, compared to mild steel, high carbon, boron steel and chromium steel were 2.28, 2.50 and 2.53 times more wear resistant, respectively. The wear characterization gives a concrete direction to customers about the required quality, properties and grade of steel for agricultural tillage discs in their specific soil condition, which is cheaper and durable. The correlation of phase transformation, hardness and hardenability with wear resistance properties rendered the three composition of steel suitable for use in specific soil condition. (c) 2007 Elsevier B.V. All rights reserved.