Effects of Niobium and Molybdenum on Microstructures after Hardeningand Wear Resistance of Austenitic Manganese Steel

ali hadji; BOUHAMLA Khedidja

Hadfield steel has been wildly used to manufacture railway crossings because of its excellent workhardening, high strength and toughness properties. The hardness of Hadfield steel is only about 20 HRC whensubjected to water toughening. This low hardness is usually associated with poor wear resistance and severeplastic deformation, as well as abrasion of the working surface of the railway crossing during the initial serviceperiod, which remarkably reduces its service lifetime. In this study we focus on the influence of niobium andmolybdenum on the phenomenon of surface hardening or work hardening and wear resistance. Thetransformation of austenite during operation, thus determines the steel operating lifetime, the rate oftransformation of austenite to martensite can introduce a compromise between ductility and wear resistance ofthe steel to support large efforts without breaking. The objective of this study is to improve the wear resistanceby abrasion and friction after heat treatment of manganese steel alloyed with niobium and molybdenum. Theaddition of niobium and molybdenum promotes secondary hardening and allows slower transformation ofaustenite during the heat treatment. The results showed that the introduction of niobium and molybdenum hasstrongly influenced the character of the structure crystallization before hardening (Part hardened) byprecipitation carbides form and finesse variables is observed in the microstructure before heat treatment andcomplete dissolution is noted after heat treatment, for the hardened part (work hardening) we observed agreater thickness and hardness compared to the base steel and net improvement in wear resistance.

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Effects of Niobium and Molybdenum on Microstructures after Hardeningand Wear Resistance of Austenitic Manganese Steel

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