Study of Magnetism in Colmonoy-6 (AWS NiCr-C) Deposit on 316LN Stainless Steel

Considerable difference in melting points between the austenitic stainless steel (SS) substrate and Ni-base Colmonoy (AWS NiCr) hardfacing alloys results in significant dilution of the hardface deposit from the substrate. In the present study, it is found that the dilution also affects the magnetic property of the deposit. Although both austenitic SS and the undiluted Ni-base hardfacing alloy deposit are non-magnetic, the deposit diluted by austenitic SS becomes magnetic. Magnetism at different dilution levels of the deposit is measured using Magnegage and Feritscope, and the results correlated with the dilution of the deposit that is estimated from its Fe and Ni contents using SEM-EDS analysis. A good correlation between dilution and magnetic property could be obtained. As dilution also affects the hardness of the deposit, it was also possible to correlate the magnetic property of the deposit with its hardness. These findings have potential application in using magnetic measurement as a non-destructive method for estimating the hardness and/or dilution of the deposit on actual components not amenable for in-situ hardness measurements. The possible origin of magnetism in the deposit layers has been examined. The small variations in the lattice parameters of the deposit with dilution (composition) could be well correlated with variation in magnetic property.