STRUCTURAL CHARACTERISTICS AT SURFACE AND BARKHAUSEN NOISE IN AISI 4340 STEEL AFTER GRINDING

Structural effects of wet and dry grinding on AISI 4340 steel have been examined by X-ray diffraction analyses, metallographic observations and microhardness measurements and these are compared with measurements of magnetic Barkhausen noise amplitudes Results have shown that Barkhausen noise measurements can be used, especially after wet grinding, for nondestructive monitoring of zones of softening, due to local heating, with transition from the initial stage of strong workhardening, with residual stress of compression, to the following stage of lower hardening with tendency to residual stress of tensile character For the range of grinding depths examined the effects of subgrain size on Barkhausen noise appear to be predominant over those of residual and internal stresses.