Development of an Innovative Carbon-Free Ecological Process as an Alternative to Explosion for Manganese Steel Hardening

Explosion hardening is currently the go-to method for increasing manganese steel hardness in critical applications such as railway turnouts. While effective, environmental considerations, sustainability, and competitiveness, are now more critical in industry, exposing this costly method’s weaknesses; transport to external specialists, explosions release greenhouse gases, lack precision, and disrupt the casting’s internal crystallographic network. Follow-up work is also required prior to installation. Consequently, there is a need for a more technological and cost-effective eco-hardening process, better matching today’s ethos and industrial decarbonization goals. This project presents an alternative to explosion treatment, ‘Single Process Hardening’ (SPH), which innovatively combines three established technologies for the first time in a single process: percussion hammering, ultrasonic waves, and shotblasting. Unlike the explosion method, SPH castings would not require follow-up work, e.g. crack repair, prior to installation. Following promising results using simulation software, several trial batches of 5m turnout frogs were cast, and divided between explosion hardening and SPH, prototype equipment being used for the latter. The following were analyzed; contact surface and cross-sectional hardness, permanent and residual stress, and tribological aspects. Empirical data was fed back into the software to improve future results through machine learning (AI). For analysis of all the castings, x-ray diffractometry, USM, hole ring and ring core methods were used to obtain an in-depth picture of the relevant metallurgical characteristics. With the new process, approximately one hour of treatment obtained the 400+/- HB obtained by explosion. Potentially, by tweaking the process, +/- 420HB could be obtained as the internal crystallographic integrity is not disrupted. The estimated reduction in the total cost with this new method is 75% less than using the explosion method. Regarding decarbonization goals, the elimination of road transport, and the use of green electricity, would make this method a valuable contributor.