DEVELOPMENT OF CRUSHER JAWS USING FERRO-ALLOY HARDFACING ON LOW CARBON STEEL SUBSTRATE

Abstract

Longer downtimes, decreased productivity and moribund mines and quarries arise due to wear of Hadfield steel components in service. Towards providing an economical and relatively indigenous substitute to Hadfield steel in the mining and minerals industries, procedures for producing hardfaced jaws using locally produced ferro-alloy hardfacing inserts and low carbon steel substrate have been established. In this work, two hardfacing samples were produced based on charge mass ratio for Fe:Mn:Cr of 2:1:1 and 7:1.5:1.5, by sand casting and open permanent mould casting processes. Prior to casting, crucible furnace was used to melt the charge materials after charge calculations. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to reveal the microstructures, compositions and phases of the alloy samples, respectively. Analysis for wear, hardness and composition showed that the cast sample with mass ratio of 7:1.5:1.5 was better due to its lower wear volume, higher hardness value and lower alloy content of 0.085 cm3, 592 HV and 30.9 %, respectively. This mass ratio was used to develop hardfacing inserts having 72.80 %Fe. 12.32 %Mn, 7.38 %Cr by sand casting. Hardness values and wear volumes of the hardfacing insert and Hadfield steel were 653 HV, 0.0069 cm3 and 517 HV, 0.0107 cm3, respectively. The inserts were welded to low carbon steel substrate by manual metal arc welding to form the hardfaced jaws. The welding was carried out intermittently using E6013 electrode at a current of 100 A and speed of 120 mm/min. Detailed geometric modeling and design analysis of a 0.1 ton/hr capacity jaw crusher for evaluating the jaws were achieved with Pro/Engineer® and Autodesk Inventor® softwares, respectively. The fixed and movable jaws had 0.3 and 0.1 kg loss in mass, respectively, after crushing 400 kg of granite in the jaw crusher developed. Cost of producing hardfaced jaws was five times cheaper than the estimated cost of producing Hadfield steel jaws locally; hence, the hardfaced jaws can economically substitute the Hadfield steel jaws in jaw crushers. The hardfacing insert and method are recommended for use in high abrasion and less impact wear applications such as crusher rolls, excavator buckets and cone crusher mantles and concaves