Hot workability and corrosion behavior of EN31 grade steel

Abstract

In the recent years across the globe, there is a remarkable shift in paradigm of manufacturing agricultural tools and accessories for farming in agricultural sectors. Most often, high carbon steels are usually used for making agricultural tools. In the present investigation, one of the used farming accessories was cut and accessed for compositional identification using spectrometer and based on its composition report, stock material (EN31 grade steel) was procured. Most of the agricultural tools especially ploughs are conventionally made using open die forging in rural areas to have intended properties. But morphological variation like size of the grain boundaries, carbide free zones, carbide rich zones and composition across the grain boundaries accompanied by forging, causes pitting corrosion. Hence the present investigation aims to study the effect of hot working at different temperatures while processing the selected EN31 grade steel on pitting potential and identifying the most suitable temperature for hot deformation and high corrosion resistance. All the processed steels exhibited both superior hardness and corrosion resistance compared to the base metal. Forged steel at 800°C has shown maximum corrosion resistance compared to steels forged at other temperatures and it may be attributed to the extent of dissolution of the carbides and uniform distribution of carbide particles in the parent matrix which act as insulator to the path of galvanic cell formation between cathodic of intermetallic particles and anodic cells i.e. parent microstructure. Even though the extent of deformation rate is found to be maximum while forging at 850°C, it has been restricted because of premature appearance of cracks, hence hot forging of base metal at 800°C is recommendable one.