Study the effect of using different quenching mediums on erosive wear behavior of high chromium white cast iron

Abstract

In order to a accomplish economically good martempering process, it is required to find a cheaper and more available alternative quenching medium for the ordinary nitrate mixture used in this process. A high chromium white cast iron, which is generally used as mill liners in mining, crushing, and cement plants, is subjected to severe conditions of wear/impact. These conditions lead to failure and reduction in part life as well as increase in the cost of repairs, therefore, it is important to enhance its mechanical properties. The effect of different quenching mediums used in martempering treatment on the erosive wear, microstructure and mechanical properties of this cast iron was studied. In this study, two types of quenching mediums were used: Nitrite mixture (50% NaNO3 + 50 % KNO3) and Hydroxide mixture (50% NaOH : 50% KOH). The specimens were austenetized at 950°C for 1 hr then the first group was quenched in nitrate mixture and the other was quenched in hydroxide mixture, both at about 350°C, for (1/2, 2, 4, 6, 8) hrs. It was concluded that the two mediums enhance erosive wear resistance, but the nitrate mixture show the best erosive wear results among the other treatments, especially at martempering about 350°C for 4 hrs.