Abstract:
This work focused on toughness and corrosion behaviour of heat treated and nickel plated mild steel to replace austenitic stainless steel for yam beater in yam pounding machine. Four standard samples were prepared for tensile and electrodeposition from the steel samples and were heated to austenising temperature of 920 ºC maintained for 60 minutes. One of the samples was air cooled while the remaining three were quenched in water and each of the samples was tempered at 450, 550 and 650 ºC for 60 minutes. After the heat treatment process, the test samples were subjected to standard test to obtain the Ultimate Tensile Strength (UTS) and toughness. Nickel
electrodeposition was carried out on the heat treated mild steel using Watt standard of bath concentration. Scanning Electron Microscope (SEM/EDS) was used to examine the surface morphology of the nickel electrodeposited samples. Corrosion behaviour of the nickel plated samples was carried out using Potentiodynamic polarization measurements in yam fluid environment. It was observed that among all the heat treatment operations, the sample heat treated at 920 ºC and tempered at the highest tempering temperature of 650 ºC gave the highest toughness value (102 MJ/m3) when compared with stainless steel of 124 MJ/m3. The sample heat treated at 920 °C and tempered at 550 oC displayed a corrosion rate of 0.022182 mm/year as against the stainless steel sample with value of 0.0031864 mm/year. The nickel deposited on the
heat treated samples enhanced corrosion resistance in the yam fluid. XRF analysis of the yam before pounding, after processing with Nickel electroplated and stainless beater shows the content of Nickel as 0.0941%, 0.109% and 0.1113% respectively. It was concluded that materials for the yam pounding beater, therefore perform better if it were both heat treated and nickel plated. Invariably, stainless steel could be successfully replaced with heat treated and nickel plated mild steel for use as yam pounding beater.
