John R Bowler et al 2008 Meas. Sci. Technol. 19 075204 doi:10.1088/0957-0233/19/7/075204
John R Bowler, Yongqiang Huang, Haiyan Sun, Jonathan Brown and Nicola Bowler
Show affiliationsThe case depth of induction-hardened steel rods has been determined using multi-frequency alternating current potential-drop measurements. Experimental results are analyzed using a model which approximates the variation in the material properties of a hardened rod by assuming that a homogeneous core is surrounded by a homogeneous case-hardened layer of uniform thickness. Experimental measurements on an untreated rod are used to estimate the core conductivity and permeability of similar hardened rods. The implicit assumption is that the material parameters in the core region are unchanged in the hardening process. The case depth is found by parameter fitting to minimize a penalty function representing the overall difference between multi-frequency potential-drop measurements and theoretical predictions. Case-depth values found nondestructively show reasonable agreement with those found using Rockwell hardness measurements on sectioned rods.
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
46.55.+d Tribology and mechanical contacts
62.20.Qp Friction, tribology, and hardness
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
Issue 7 (July 2008)
Received 14 January 2008, in final form 6 May 2008
Published 12 June 2008
John R Bowler et al 2008 Meas. Sci. Technol. 19 075204
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