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According to tooling industries, grinding is the most effective and economical machining for AISI D2 tool steel owing to its low thermal conductivity. The first objective is to investigate the effect of grinding environments on surface integrity of AISI D2 tool steel. Grinding performance like force ratio and grinding temperature was investigated under wet and dry environments. The second objective is to qualitatively assess the thermal damage of ground surface using non-destructive hysteresis loop (HL) technique. The result shows that higher force ratio and surface roughness were obtained under flood grinding. Maximum thermal damage in terms of drastic variation in microstructure and microhardness were observed under dry grinding owing to serious plastic deformation at higher grinding temperature. HL outcomes like lower average permeability, higher coercivity and remanence were obtained with higher thermal damage on ground surface. Finally, linear correction was obtained between HL outcomes and microhardness of ground samples.

The research goal of present experimental work was to analyse the variation in magnetic response (at different magnetising frequency and magnetic field intensity) of IS-2062 steel of grade B upon friction stir welding (FSW). Tungsten carbide tool having 15 mm shoulder diameter was used to weld the steel plates having 3 mm thickness with welding speed of 150 mm per minute and revolving speed of 800 revolutions per minute. Welded steel plates were characterised using Barkhausen Noise analyser. Magnetic response of material, before welding and after welding was recorded in terms of Barkhausen Noise signal parameters that are root mean square (rms) value of signal and number of pulses. Both the signal parameters was observed to correlate well with grain refinement and changes in micro-hardness upon FSW of steel at different analysis parameters such as magnetic field intensity and excitation frequency.

Signal processing of magnetic Barkhausen noise was performed to reveal the useful information content of the signal which would otherwise difficult due to stochastic nature of the signal. Magnetic Barkhausen noise signal was measured from different heat treated steel samples which were further processed to investigate the effect of heat treatment on Barkhausen noise signal. The dependence of Barkhausen signal upon magnetising frequency was also discussed in terms of RMS value of Barkhausen noise envelope. Variation in the RMS value of the Barkahusen noise profile with magnetising frequency and mechanical properties was explained using micromagnetic theory. The present study shows that magnetic Barkhausen noise signal depends upon mechanical properties as well as on magnetising frequency which needs to be optimised in order to use magnetic Barkhausen noise as a characterisation tool.

The goal of present research work is to study the variation in the shape of hysteresis loop owing to change in the analysis parameter i.e., magnetising frequency and applied magnetic field strength upon pack carburised low carbon steel samples. Pack carburised heat treatment performed at three different temperatures to induce varying hardness into steel samples. Hysteresis loop characteristics such as coercivity, permeability, power loss and remanence were measured in a wide range of magnetising frequency and magnetic field intensity. Coercivity is observed to increase with increase in magnetising frequency and applied field strength. In low-frequency range ( 1 Hz) results into increase in remanence and power loss. However, with an increase in magnetic field strength both remanence and power loss were found to increase.

An experimental study was undertaken to investigate the critical behaviour of Barkhausen noise (BN) parameters after surface grinding of medium carbon steel. The relations between residual stress and BN parameters were discussed in terms of degree of plastic deformation. The best parameter for residual stress evaluation is root mean square (rms) value of BN signal. In the present work, when the residual stress is more than the yield strength of the work material, the correlations between BN parameters, downfeed, residual stress, grain elongation and change in microhardness upon grinding have been investigated. X-ray diffraction (XRD), metallographic study and microhardness measurement of ground samples were studied. BN parameters were shown to increase with plastic deformation and then decrease with elevated level of plastic deformation. The results are explained in terms of mechanism that affects dislocation density as a function of grain elongation or plastic deformation and interaction of domain walls.