Effects of surface treatment on tensile properties and fracture behavior of two high-strength steels

In this paper, the extrinsic influence of high-energy mass finishing surface treatment, referred to as ‘HEMF’, on the tensile properties and resultant fracture behavior of two high-strength steels that are viable candidates for both selection and use in a spectrum of high-performance applications is presented and discussed. HEMF is essentially a surface-treatment process wherein fine objects, microscopic in dimension, are made to impact at a very high speed and force with the surface of the chosen specimen. Test results reveal that the innovative surface treatment did increase the yield strength, tensile strength and ductility of the chosen stainless steel 17-4 PH. For alloy steel 300M, both the yield strength and tensile strength decreased in the longitudinal orientation but revealed an increase in the transverse orientation. Surface preparation was observed to have a detrimental influence on the ductility of alloy steel 300M. The kinetics governing tensile response and fracture behavior, at both the macroscopic and fine microscopic levels, are presented in light of the nature of loading, the presence of surface treatment and intrinsic microstructural effects.