TO STUDY THE SLURRY EROSION OF DUAL PHASE STEEL

Abstract

In the present study, investigations have been carried out on the effect of various heat treatments on the structure, mechanical properties and erosion behavior of dual phase steel. The material used in this investigation is dual-phase steel, having weight % C- 0.1 Mn- 0.5 Si- 0.25 P- 0.04 S- 0.04 Dual phase (DP) steels consist of hard martensite islands embedded in a relatively soft and ductile matrix of ferrite. They have recently emerged as a potential engineering material system for automobile and other engineering applications. Low carbon dual phase steels have found application in fabricating pipe-lines for transportation of mineral slurry and other wear resistant applications. In a recent study they have also been found to hold good potential for use as farm implements where strength and wear resistance become of a great concern. The present work aims at studies to study the slurry erosion characteristic of dual phase steel which is already heat treated at intercritical annealing temperature of 820°C with different soaking time followed by water quenching. The heat treated steel is tested for ductility (%El), tensile strength (UTS), microstructure and their effect on erosion behavior. The heat treated material which shows minimum weight loss were studied by using optical microscope to identify the different micro constituents such as martensite, ferrite, pearlite etc. The mechanisms of erosion have been investigated using Scanning Electron Microscope (SEM). It is observed that in the first stage of erosion, plastic deformation occurs by Extrusion and Microforging mechanism at the surface of dual phase steel by impact of silt particles. This combined deformation of microforging and extrusion will produce indented concavities and protruding thin platelets. These protruding thin platelets will then be partially impinged off by the subsequent impinged deformation. Therefore, after continuation, the surface morphologies will finally consist of many overlapping irregular concavities and residual. protruding thin platelets attached onto the nearby surface.