The repetitive impact wear of steels for hydro-powered mining machinery

• Main Author: Fricke, Roland
• Other Authors: Allen, Colin
• Format: Dissertation
• Language: English
• Published: University of Cape Town 2016
• Subjects: Materials Engineering
• Online Access: http://hdl.handle.net/11427/18214

The repetitive impacting of solid components in industry can result in wear damage which may significantly limit service life. Impact wear problems have been encountered in hydro-powered stoping equipment (eg rockdrills and impact rockbreakers) developed for deep level gold mining in South Africa. This research project was a study of the repetitive impact wear of reciprocating valve components (eg poppet valves within the impact rockbreaker) under simulated conditions. A laboratory apparatus, capable of producing impacts varying in energy from 2 - 5 J and varying in frequency from 5 - 50 Hz in an aqueous environment (distilled water), was designed and built for this purpose. Impact tests were conducted in order to: a) rank materials according to impact wear resistance, b) to determine modes and mechanisms of wear, c) to determine material, microstructural, design and operating parameters of importance in minimising wear, d) to make recommendations concerning the above, to facilitate productivity and longlife of poppet valves within impact rockbreakers. The materials selected for testing (817M40, 1210 and AISI 304, AISI 431 and AISI 440C) are steels currently used by the gold mining industry in different applications and known to perform satisfactorily in service. These materials are not all ideally suited to application in valves. They were chosen in order to illustrate how different steel compositions, microstructures and heat treatments influence the rate and mode of wear.