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Thick cladding of copper is required for diverse applications, however, only a handful of processes can be used for bulk material cladding. This study has been undertaken to suggest a better alternative method for cladding thick layer of copper on aluminium substrate. Cladding of 3 mm thick layer of copper on 6 mm thick aluminium substrate has been successfully performed using friction stir welding process (FSW). Detailed microscopic study, XRD and microhardness evaluation of the samples proved the quality of clad layer. Interestingly even after three FSW passes no substrate material could reach near the top of clad layer.

Ultrasonic vibration-assisted dry grinding is a sustainable hybrid manufacturing technology that decreases the negative environmental impact of coolant, reduces manufacturing costs, and improves surface integrity. The present investigation analyses the mechanisms associated with ultrasonic vibration-assisted dry grinding of AISI D2 tool steel with an alumina grinding wheel. It also compares the influence of traditional dry grinding and traditional wet grinding modes with the ultrasonic vibration-assisted dry grinding mode at different ultrasonic vibration amplitudes. Ultrasonic vibration was applied to the sample in the longitudinal feed direction. Further, kinematics of the abrasive grit path during the traditional grinding and ultrasonic vibration-assisted dry grinding is presented schematically. In this research, the impacts of ultrasonic vibration amplitude as well as the depth of cut on the process yields such as ground surface topography, grinding force, specific grinding energy, force ratio, surface finish, microstructure, and hardness were investigated experimentally. Experimental results revealed that the highest decline in tangential and normal grinding forces in ultrasonic vibration-assisted dry grinding at ultrasonic vibration amplitude 10 µm and the reduction in surface roughness parameter ( Ra, Rq, and Rz) in ultrasonic vibration-assisted dry grinding was 43.23%, 42.59%, and 33.69%, respectively, in comparison to those in traditional dry grinding and 26.35%, 26.94%, and 27.48%, respectively, in comparison to those in traditional wet grinding. It was observed that ultrasonic vibration-assisted dry grinding is beneficial as the profile produced by ultrasonic vibration-assisted dry grinding has a comparatively flat tip, and profile points are shifted to the bottom of the mean line. This study is expected to assist ultrasonic vibration-assisted dry grinding of hard materials.

Common welding processes that are used for cladding causes dilution and therefore, there is a need to explore new processes of cladding. In this work, friction stir welding process has been used to successfully clad 3 mm thick copper sheet on a 6 mm thick mild steel substrate. The process is different from lap welding, not only because of its intended purpose, but also because several FSW passes are needed to cover the entire surface of the substrate. After one FSW pass, successive passes were carried out to cover a wider width of the clad layer by offsetting the tool. Metallurgical examination of the transverse cross-section of cladded samples was carried out using optical microscopy, SEM–EDS, microhardness test, and XRD. Surface jetting type features, normally seen in explosive welding, were observed at the interface of the two materials. The average grain size of steel substrate below the clad layer for both single and triple passes showed refined grains with size of 3.9 µm and 4.2 µm respectively indicating an improvement of more than 60% over the base steel. Although there was plastic flow of material, the substrate material could not make to the top surface of the clad layer. XRD analysis confirmed no new phases were observed on the top surface of the clad layer after cladding. However, the interface region on the transverse cross-section confirmed the presence of Cu0.8Fe0.2 and Cu0.3Fe1.7 intermetallics. Microhardness for copper clad region remained nearly same across all the passes. However, for the steel substrate, higher hardness values were found near the stir zone due to grain refinement for single pass clad while for double and triple passes, a slight reduction was recorded possibly due to metal transfer across the boundary upon second and third passes.

In the precision fabrication industries, ultrasonic vibration-assisted grinding is widely utilized for the finishing of “difficult-to-cut” materials due to its intermittent cutting mechanism and brittle-to-ductile mode machining. In this study, a two-dimensional finite element model (FEM) of single grit ultrasonic vibration-assisted dry grinding (UVADG) and conventional dry grinding (CDG) of AISI D2 steel has been developed, which taken into account the influence of longitudinal ultrasonic vibration on the workpiece with variable downfeed. The effects of ultrasonic vibration and downfeed on the chip formation mechanism, temperature field, grinding force, and equivalent stress and strain were evaluated by analytical and simulation methods. The results show that the formation of the grinding chips under UVADG is much shorter and straighter than CDG mode at all respective downfeed. The validation experiment compared the simulated and experimental grinding force in both grinding modes to verify the reliability of the FEM results. The validation results demonstrate that the FEM model can accurately describe the single grit UVADG and CDG grinding. At each downfeed, the CDG mode has generated a larger equivalent plastic strain than the UVADG mode, resulting in a higher thermomechanical load on the workpiece. According to the findings, UVADG mode has the least plastic damage on the ground surface, which may improve the surface integrity of the ground component.

Nowadays, precision manufacturing industries are required faster surface inspection tools for the achievement of high productivity. In this context, the Barkhausen noise (BN) technique is adopted as a quick response technique in the grinding for qualitative evaluation of surface integrity of AISI D2 tool steel. Present work investigates the effect of eco-friendly coolant, i.e., cryogenic, on surface integrity of ground sample in the plunge grinding mode at different downfeed and compared with dry and wet environments. Surface integrity was assessed in respect of surface roughness, microstructure, and microhardness. Magnetic response of ground surface was reported by Barkhausen noise analyzer in the form of root mean square (rms), peak, and number of pulses. From the outcomes, it was perceived that no significant variations were found in the microstructure and microhardness of the ground surface and subsurface after cryo-grinding owing to lower thermo-mechanical loading. Besides, lower surface roughness was obtained in the case of cryo-grinding because of thermal softening effect. A linear correlation between BN input parameters, i.e., magnetic field intensity and BN responses at different magnetizing frequency could be achieved. Finally, better BN responses, including higher rms, peak, and number of pulses, were found under the cryogenic environment.

Grinding generates a lot of heat in the grinding zone area during operation. Therefore, it is important to keep the temperature under control by using various cutting fluids to get a good ground surface quality. The existence of a stiff air layer surrounding the abrasive wheel is known to waste most of the cutting fluid supply in the interface area between the abrasive wheel and workpiece. Due to the high grinding speed, stiff air layers prevent cutting fluids from entering the interface area. Hence, to enhance the grinding performance, cryogenic cooling has been introduced to improve the penetration into the stiff air layer. The current work investigates the grindability of the ground surface of AISI D2 tool steel under different environments: dry, wet, and cryogenic, regarding grinding forces (i.e. tangential and normal force), specific grinding energy, and surface characterisation. This paper also proposed a method to evaluate image-based Abbott–Firestone curve (bearing area curve) parameters to characterise the ground surface topography. Significant reductions in grinding forces (64%–67% and 44%–50% in Ft, 54%–58% and 34%–39% in Fn), low specific grinding energy (64%–67% and 44%–50%), decrease in surface roughness (46%–51% and 30%–36% in Ra, 37%–41% and 31%–35% in Rz), improved 2D and 3D roughness profiles and higher bearing area ratio (89.54%) were observed at 40 µm downfeed in cryogenic cooling environments compared to dry and wet environments, respectively. Thus, observations show the importance of cryogenic cooling across the experimental domain.

In recent years, increasing demand for biodegradable lubricants has been observed in precision machining owing to ISO 14000, which draws more attention toward the operator’s health and environmenta...

Nowadays, Minimum Quantity Lubrication (MQL) technique with eco-friendly groundnut oil is adopted in precision machining to tackle the operator health and environmental issues owing to petroleum based cutting fluid. The effectiveness of this technique depends on mixture quality of MQL mist. Hence, the objective of present work is to optimize the MQL mist parameters i.e. air pressure (P), flow rate (Q), and stand-off distance (ds) to minimize the effect of MQL based plunge grinding on hardened AISI H13 tool steel in terms of lowest grinding force, specific energy, grinding temperature, and surface roughness using grey relational analysis. Taguchi’s L16 orthogonal array was utilized for conducting the final experiments and mist parameters varied through four levels include P (2, 3, 4, and 5 bar), Q (50, 100, 150, and 200 L/h) and ds (40, 50, 60, and 70 mm). Further, experimental analysis was carried out to compare the effect of optimal and worst mist parameters on ground surface and microchip by using microhardness, scanning electron microscope, and atomic force microscopy. According to validation test, P: 4 bar, Q:200 mL/h, and ds:50 mmare optimal mist parameters for multi-response variables of MQL grinding. Effective mist quality i.e. average droplet size of 51.03 μm was obtained at nozzle angle of 12°. Excellent ground surface quality with negligible microhardness variation and no wear tract microchip were observed under optimal mist setting.

The present investigation utilizes the micromagnetic Barkhausen noise and hysteresis loop technique to evaluate the surface integrity of ground steel. The grinding experiment was performed on IS-2062 steel by varying the process parameters. The magnetic parameters such as root-mean-square value of Barkhausen noise signal and average permeability of hysteresis loop are correlated with surface integrity such as metallurgical changes, surface roughness, and residual stress of the ground surface. The result shows that microstructural alteration in the ground surface has insignificant effect on the measured magnetic parameter. The surface roughness value is obtained in the range (0.4279-0.6498 µm) which is very small and thus having insignificant contribution for variation in magnetic parameters. However, root-mean-square value as well as average permeability increases with the increase in peak shift of the XRD peak. The correlation coefficient between root-mean-square value and peak shift was observed to be 0.9707, and those between average permeability and peak shift was 0.9510. The present study shows that Barkhausen noise signal and hysteresis loop technique provides a new dimension in the characterization of the ground surface.

Thermal damage restrict the capability of grinding in achieving the desired production rate; therefore, the present study focuses on the employment of a non-destructive Barkhausen noise (BN) technique in the assessment of thermal damages produced from grinding of hardened IS 2062 steel under dry (no lubrication) and wet (with lubrication) conditions. Optical microscopy along with microhardness measurement was utilized to reveal the microstructural and hardness alternation occurred in the ground and subsurface of sample. X- ray diffraction peak shift was measured and used for qualitative analysis of residual stress. Furthermore, surface topography was obtained by scanning electron microscope. The magnetic response from ground surface were measured in terms of Barkhausen noise (root mean square) and hysteresis loop (average permeability). The result shows very poor magnetic response from ground hardened steel due to higher carbon content. A non-linear variation is observed between peak shift and root mean square value of Barkhausen noise. However, average permeability derived from hysteresis loop shows good correlation with the peak shift with a correlation coefficient of approximately 0.8149.

Surface integrity characterization of manufactured component is very important as it significantly affects the in-service performance of the component. Till now, surface integrity was evaluated using conventional measurement technique like microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester. But, this technique being laboratory based cannot be used for in-service monitoring of the surface integrity. The present study focuses on the characterization of surface integrity upon electric discharge machined sample using non-destructive magnetic Barkhausen noise technique. Electric discharge machining was performed in die-sinking mode on die steel using copper–tungsten electrode (negative polarity). Experiment was performed by selecting different levels of peak current, gap voltage and pulse on time. Surface integrity characteristics like microhardness change, residual stress, microstructural alteration and surface roughness were analysed using microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester, respectively, and were then correlated with magnetic parameter like root mean square value and peak value obtained from Barkhausen noise signal. The results show a good correlation between magnetic parameter (RMS and Peak value) of Barkhausen noise with the microhardness and surface roughness of the machined sample.

The variation of magnetic Barkhausen noise (MBN) response of different regions of the gas metal arc welded ferritic stainless steel SS409L plate in terms of number of pulses and root mean square value with the variation of MBN analysis parameters (magnetic field intensity and magnetizing frequency) have been investigated in the present work. Five different values of magnetic field intensity 250, 500, 750, 1000 and 1250 Oe at the constant magnetizing frequency of 25 Hz and four different values of magnetizing frequency 10, 20, 30 and 40 Hz at a constant magnetic field intensity of 800 Oe were used as MBN analysis parameters. It was found that MBN response depends upon the magnetic field intensity and magnetizing frequency as well on grain size and microhardness of different regions.

Steel is one of the most widely used engineering materials and it is popularly welded in fabrication industries using Gas metal arc welding (GMAW) process. The microstructure obtained in the heat affected zone is often characterized with large grain size. Depending on the GMAW process parameters, the weld metal may consist of Allotrimorphic ferrite if the heat input is high. Therefore, the weld metal and the heat affected zone may have poor weld metal toughness. Efforts have been made to modify the microstructure of the weld metal by performing friction stir processing. Initially bead on plate welding was performed on mild steel plate using GMAW process using standard 1.2 mm consumable wire and CO2 as the shielding gas. The top surface of the weld was processed using a tungsten carbide tool. The weld reinforcement was removed using milling process and the area to be processed was made smooth before performing FSP. The plate was secured in an FSW machine and friction stir processing was carried out with a FSW tool having pin length of 2 mm. The GMAW weld and the weld that has been subsequently modified using FSP were characterized using standard techniques. The microstructure of the top face showed an improvement from Widmanstätten to fine equiaxed structure after being friction stir processed. The microstructure in the HAZ also got refined. It is expected that this structure would improve the mechanical properties of the weld particularly on the surface.

Hysteresis loop analysis technique, being a non-destructive testing technique is more beneficial than the destructive testing techniques to characterise the welded plate. In this study, the ferritic stainless steel AISI 409L plate was butt welded by gas metal arc welding process. Hysteresis loop analysis technique was used to study the microstructures and microhardness of the base metal region, heat affected zone and weldmetal zone. This study has been carried out at four different values of magnetic field intensity 250, 500, 750 and 1000 Oe. The effect of variation of magnetic field intensity on the hysteresis loop characteristics (average maximum flux density and core loss) has been investigated for base metal, heat affected zone and weldmetal zone. It was found that for each region, the average maximum flux density as well as core loss increases on increasing magnetic field intensity. Also, the variation of average maximum flux density is inversely proportional to the microhardness of the region at each value of magnetic field intensity.

Characterisation of the welded plate by Non-destructive testing technique are gaining more popularity over destructive testing. In this study, the variation in the hysteresis loop behaviour were examined with the variation of magnetic field intensity on the base metal, heat affected zone and weld metal regions of gas metal arc welded ferritic stainless steel plate. The behaviour of hysteresis loop characteristics such as average permeability, remanence and coercivity have been investigated and it was found that these characteristics depend upon the grain size and microhardness as well as magnetic field intensity. Coercivity of each region vary in proportion with the variation of magnetic field intensity and inversely proportional to the grain size, but the variation of other hysteresis loop characteristics with the magnetic field intensity in each region is irregular.

Economical welding of dissimilar titanium alloys has always been a challenge for the aerospace and nuclear industries, where these alloys are extensively used because of their high strength-to-weight ratio. The present investigation deals with the development of a novel shielding setup for the successful welding of commercially pure titanium (α-phase) to Ti–6Al–4V ((α + β)-phase) without any atmospheric contamination using gas tungsten arc welding. Commercially pure titanium (CP-Ti) and Ti–6Al–4V sheets of 3 mm thickness were butt-welded autogenously and using CP-Ti filler metal. Metallographic studies, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, microhardness measurements, tensile testing, and fractography were carried out to understand the evolution of the microstructure and characterize the welds. Grain coarsening in heat-affected zone and weld, and variation in the distribution of phases were observed from the optical micrographs and energy-dispersive X-ray spectroscopy spectrum of different zones. An unsymmetrical variation of hardness was observed in the weld region, and a 15% reduction in hardness value (280 HV0.2) was obtained at the weld center of using filler metal weld than autogenous weld. Comparable strengths with little drop from as-received CP-Ti (307 MPa) were observed for welded specimens. Welds produced using CP-Ti filler metal (272 MPa) had higher strength than autogenous welds (214 MPa). As-received tensile specimens fractured nearly from the center of gauge length, but welded tensile specimens fractured near the base/heat-affected zone boundary of the CP-Ti side.

Welding process parameters are the controlling factor for percentage dilution and weld bead geometry (bead width, bead height and penetration). Percentage dilution and weld bead geometry are very important factors to determine the quality of the joints. Present work aims to investigate the effect of welding speed (300, 400 and 500 mm/minute) on percentage dilution and weld bead geometry. Gas metal arc welding of ferritic stainless steel SS409L with austenitic stainless steel filler wire ER304L using pure argon gas has been done. The study of percentage dilution and weld bead geometry has been carried out. It has been found out that with increasing welding speed, bead width, bead height and penetration decreases but percentage dilution first increases with the welding speed parameter and then decreases with further increase in these values.

In the present experimental work pack carburized low carbon steel (IS-2062) plates were characterized using magnetic barkhausen noise analysis. Low carbon steel samples were pack carburized under different conditions by varying the temperature. BN analysis along with hysteresis loop measurement was carried at different magnetizing frequency and magnetic field strength. Metallographic analysis was also performed to correlate the magnetic barkhausen noise results. Variation in microstructural changes in steel plates upon pack carburizing heat treatment clearly reflect their effect on BN signal and hysteresis loop characteristics such as permeability and coercivity.

Objective of current study is to analyse the effect of excitation frequency, magnetic field intensity and waveform on the hysteresis loop and Barkhausen Noise signals. As the property of ferromagnetic material especially the hysteresis loop and Barkhausen noise depends on microstructure, excitation frequency and magnetic field intensity. In this study the hysteresis loop and Barkhausen noise of the mild steel sample were experimentally measured by varying the frequency, intensity and waveform using magnetic Barkhausen noise analyser. Sinusoidal and triangular waveform were applied in varying frequency (0.1 Hz to 0.4 Hz) and intensity (250 Oe to 1000 Oe) for hysteresis loop whereas for Barkhausen noise analysis frequency varies from 20 Hz to 50 Hz and intensity varies from 250 Oe to 1000 Oe. Characteristics of hysteresis loop and magnetic Barkhausen noise depends upon magnetizing parameter and waveforms were explained with the help of micro magnetic theory.

Present work aims to increase the weld strength by combining Metal Inert Gas Welding (MIG) and Shielded Metal Arc Welding and reduce the dependence on inert gas used in MIG welding by relying on the flux of electrode to provide the shielding effect. It also aims to reduce the HAZ by reducing the melting of base metal, instead filling the grooves by molten mild steel electrode which is used in SMAW. Steel plates (IS-2062 grade) of 6mm thickness were welded in a single pass by placing a mild steel electrode (E6013) between them. The Shielding Gas used was CO2. Pre-weld preparations included making grooves with various included angles and Root gaps. Characterization was done using Optical Microscope. Micro-hardness test was carried out to confirm the above results. As flux of the electrode forms shielding gas and slag on the top of the weld, flow rate of the gas can be reduced to a much lower extent.

In grinding process, cutting fluids play an important role to control high grinding zone temperature. However, their use causes detrimental effect on the operator’s health and environment. On the other hand, dry grinding not only results in thermal damage to ground surface but also deteriorates the surface quality and dimensional accuracy of the ground component. The possible solution is to apply cutting fluids using minimum quantity lubrication (MQL) technique. The objective of present research work is to investigate and compare the effect of different grinding environments: dry, flood, MQL with deionized water (DIW), MQL with liquid paraffin oil (LP), and MQL with castor oil based on vegetable oil (VO) during grinding of hardened H13 hot die steel. Grinding performance was evaluated in terms of specific grinding force, specific grinding energy, grinding force ratio, surface roughness, and microhardness. Ground surface and debris morphology were also analyzed using scanning electron microscope, atomic force microscope, and energy-dispersive X-ray spectroscopy to validate the grinding performance. The results showed that MQL-VO grinding leads to minimum specific grinding force, specific grinding energy, and grinding force ratio. Further, surface roughness was considerably reduced under MQL-VO grinding, where Rɑ and Rz were 0.245 μm and 1.846 μm, respectively. AFM analysis indicated that the surface roughness of MQL-VO grinding was nearly 29.88% less as compared to dry grinding. Smooth ground surface topography, as well as long, thin, and no wear track grinding debris, were observed under MQL-LP and MQL-VO conditions. Moreover, dry grinding resulted in lower microhardness in comparison to other grinding conditions.

Fly ash (FA), the solid waste resulting from combustion of coal in thermal power plants is a by-product produced in massive quantities across the world. It is considered as an environmental pollutant. Owing to its bad effects on the environment, research is being conducted all over the world for the utilisation of FA. The present work emphasizes the utilisation of FA as reinforcement in coppe rbased surface composite fabricated by friction stir processing (FSP). The properties of fabricated composite and its environmental impact through leaching test have also been reported in the present study. A groove of known dimension was machined at the centre of the plate (6 mm thickness) for compaction of the high amount of FA (almost 18 vol %), processed by FSP. The microstructural features of the fabricated composite were observed by optical and scanning electron microscope revealed equiaxed and fine grain structure with no concentration gradient, agglomeration and segregation along the grain boundary. The stir zone (SZ) was engulfed with particulate along with clean interface and excellent bonding. The XRD pattern revealed no intermetallics or in situ products except copper and particulate. Vickers microhardness tester machine adjudged significant improvement in hardness. The composite showed higher tensile strength and lower ductility as compared to copper. Enhancement in oxidation and corrosion resistance was also observed whereas electrical conductivity decreased as evaluated by four probe method. The pin on plate unidirectional dry sliding wear test was performed to evaluate the wear loss. The wear resistance of the fabricated composite improved substantially. The worn surface was observed by scanning electron microscope to have a detailed understanding of wear mechanism. Further through leaching test, it was observed that concentration of leached out metals was far below as specified in Indian legislation.

Present work aims to assess the applicability of Barkhausen noise technique for assessment of friction stir weld characteristics. Steel plates (IS-2062 grade) were joined using friction stir welding process at various tool rotational speeds (550 to 700 rpm) while other parameters were kept constant. As-received material and welded steel plates were characterized using Barkhausen noise technique, metallographic inspection, and micro-hardness testing. Friction stir welding resulted in grain refinement which leads to higher hardness in all welded samples in comparison to the base metal. The nature of residual stress as obtained from X-ray diffraction analysis was compressive. Compressive residual stress and higher hardness in welded samples clearly depicted changes in Barkhausen noise signal profiles in terms of peak amplitude and peak position. Variation in root mean square value of Barkhausen noise signal is explained in terms of induction of compressive residual stress and microhardness.

Although copper has its use in many industrial and functional applications, but its low wear resistance limits its potential application. Hard particulates are generally reinforced in bulk copper to increase its wear resistance but it tend to decrease its toughness. Thus the present research focuses on synthesis of copper based surface composite by friction stir processing. Zircon sand was used as reinforcement in copper as it is hard and fairly inexpensive. To prepare the composites, a groove of defined dimension was machined in the copper plate for compaction of zircon sand (18 vol%) at the centre of the plate. After filling the zircon sand in grooves, friction stir processing technique was employed to reinforce it in copper. For microstructure analysis, XRD, microhardness and wear characterization, specimens were cut from the processed portion of the plate. The micrograph obtained by optical and scanning electron microscope revealed equiaxed and fine grain structure in stir zone with no sign of concentration gradient, aggregation and segregation of particles. XRD pattern revealed no peaks corresponding to intermetallics or interfacial reaction products. The microhardness and wear resistance of fabricated surface composite improved significantly as compared to pure copper. The micrograph of worn surface was also analysed to investigate the predominant wear mechanisms. Adhesion and delamination wear were predominant wear mechanisms in pure copper whereas these wear mechanism was not significant in Cu/Zircon composite.

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 shape of the Magnetic Barkhausen Noise (MBN) profiles has been compared for two different methods of MBN measurements in order to reveal the true extent of the influence of different carbon-content related microstructures on the magnetisation process. The MBN profiles were measured using high frequency and low frequency MBN measurement systems on samples from low carbon 18CrNiMo5 steel and high carbon 42CrMo4 steel heat treated by isothermal annealing, spheroidising annealing and quenching and tempering processes. The high frequency MBN (HFMBN) profile shows only a single peak for all the samples due to insufficient applied magnetic field strength and shallow skin-depth of detection of HFMBN signals. The low frequency MBN (LFMBN) profile shows two peaks for all the samples due to larger magnetisation range revealing the difference in the interaction of domain walls with different microstructural features such as ferrite, pearlite, martensite and carbides. The shape of the LFMBN profile shows systematic and distinct variation in the magnetisation process with respect to carbon content and different microstructures. This study shows that the LFMBN profile reveals distinct changes in shape which could be successfully used for characterisation of different microstructural phases in ferritic steels.

Material properties of IS 2062 steel plates after friction stir welding has been characterized by hysteresis loop characteristics at three different frequency range; low frequency, medium frequency and high frequency range. Magnetic field was applied with sinusoidal waveform and triangular waveform over base metal and friction stir welded sample for comparative analysis. Rectangular sample of 3 mm thickness were welded using tungsten carbide tool having 15 mm shoulder diameter at 800 RPM and 150 mm/min welding speed. Micro-hardness testing and metallographic study of welded samples were also performed to study the effect of change in material properties on magnetic response of material. Grain refinement upon friction stir welding changed the microhardness of weld nugget. Depth of penetration of external magnetic field at three different frequencies ranges not only changed the shape of hysteresis loop but also resulted into wide variation in hysteresis loop characteristics such as permeability, remanence, average maximum flux density and core loss.

The influence of applied magnetic field strength and frequency response of the pick-up coil on the shape of Magnetic Barkhausen Noise (MBN) profile have been studied. The low frequency MBN measurements have been carried out using 5 different MBN pick-up coils at two different ranges of applied magnetic field strengths on quenched and tempered (QT) and case-carburised and tempered (CT) 18CrNiMo7 steel bar samples. The MBN pick-up coils have been designed to obtain different frequency response such that the peak frequency response varies from ∼4 kHz to ∼32 kHz and the amplitude of low frequency signals decreases gradually. At lower applied magnetic field strength of ±14,000 A/m, all the pick-up coils produced a single peak MBN profile for both QT and CT sample. However, at higher applied magnetic field strength of ±22,000 A/m, the MBN profile showed two peaks for both QT and CT samples for pick-up coils with peak frequency response up to ∼17 kHz. Also, there is systematic reduction in peak 2 for QT sample and asymmetric reduction in the heights of peak 1 and peak 2 for CT sample with increase in peak frequency response of the pick-up coils. The decreasing sensitivity of pick-up coils with increasing peak frequency response to MBN signal generation is indicated by the gradual reduction in width of MBN profile and height of peak 2 in the QT sample. The drastic reduction in peak 1 as compared to peak 2 in the CT sample shows the effect of decreasing low frequency response of the pick-up coils on lowering skin-depth of MBN signal detection. This study clearly suggests that it is essential to optimise both maximum applied magnetic field strength and frequency response of the MBN pick-up coil for maximising the shape of the MBN profile for appropriate correlation with the magnetisation process and hence the material properties.

The variation of heat input on microstructure and mechanical properties in gas metal arc welding of ferritic stainless steel (grade 409 L) using two different austenitic filler wires ER304 L and ER308 L have been discussed in this work. Three different heat input parameters of 0.3, 0.4 and 0.5 kJ mm−1 are used in this experimental work and the effect of heat input on the properties of weldment were investigated using metallographic study and mechanical testing. Percentage dilution, chromium nickel ratio, microstructure, microhardness and tensile properties were all found to be affected by the heat input. It was observed that welded sample with heat input of 0.4 kJ mm−1 possesses superior mechanical properties irrespective of type of filler wire used. Mechanical properties obtained by using 304 L filler wire were found to be better than those obtained using 308 L filler wire, irrespective of heat input provided during welding.

The full width at half maximum (FWHM) of XRD profiles is used to characterize different material properties and surface integrity features. However, there is no literature available that discusses the nature of the correlation between the FWHM of XRD peaks with induced surface residual stress upon grinding with simultaneous occurrence of plastic deformation, formation of white layer, grain elongation, change in microhardness, etc. AISI 1060 steel samples were ground under different grinding domains, i.e. conventional abusive grinding, conventional grinding, cBN grinding and high speed grinding with moderately deep cut. Induction of tensile and compressive residual stress, microstructural changes, white layer formation, grain refinement, plastic deformation, grain elongation and change in microhardness were observed upon grinding AISI 1060 steel. A correlation was established between the FWHM of XRD peaks and surface residual stress when simultaneous changes in microhardness and microstructure, grain elong...

An experimental study was undertaken to compare the role of process parameters on the grindability of bearing steel (unhardened and hardened) in conventional grinding domain with particular emphasis on surface integrity. Surface residual stress on the ground specimens has been assessed using X-ray diffraction technique and Barkhausen noise analysis. The aim of this article was to compare the applicability of Barkhausen noise analysis technique to assess the state of residual stress with simultaneous change in microstructure along with the formation of white layer, microhardness, the incorporation of plastic deformation, etc. The results indicate a significant effect of downfeed and work speed on surface integrity parameters like residual stress, microstructure, and microhardness. Residual stress varied in the present work over a domain of 50–700 MPa. Despite simultaneous variation in the microhardness, microstructure, and residual stress during grinding, a linear correlation could be established between Barkhausen noise parameters and residual stress.

The Barkhausen Noise Analysis (BNA) technique has been utilised to assess surface integrity of steels. But the BNA technique is not very successful in evaluating surface integrity of ground steels that exhibit poor micro-magnetic response. A new approach has been proposed for the processing of BN signal and two newly proposed parameters, namely ‘count’ and ‘event’, have been shown to correlate linearly with the residual stress upon grinding, with judicious choice of user defined ‘threshold’, even when the micro-magnetic response of the work material is poor. In the present study, residual stress induced upon conventional plunge surface grinding of hardened bearing steel has been investigated along with unhardened bearing steel for benchmarking. Moreover, similar correlation has been established, when primarily compressive stress is induced upon high speed grinding using cBN wheel with moderately deep cut suppressing the micro-magnetic response from the ground medium carbon steel as the work material.

Application of external magnetic field over a ferromagnetic material results in change in its global magnetization. Change in global magnetization occurs due to motion of magnetic domain walls to align themselves in the direction of applied magnetic field. The motion of magnetic domain wall generates hysteresis loop consisting of magnetizing curve and de-magnetizing curve. Hysteresis loop is generally characterized by its characteristics such as remnance, coercivity and permeability. In the present study, hysteresis loops were obtained from Ni based sample at different magnetizing field intensity and magnetizing frequency. Hysteresis loops were clubbed together to study the changes in shape owing to variation in magnetizing field strength and magnetizing frequencies. Changes in applied magnetic field strength and magnetizing frequencies affect the process of change in global magnetization process of material. Variation in hysteresis loop shape and its characteristics such as coercivity, remnance and permeability clearly reflects effect of magnetizing field intensity and frequency. A good correlation was obtained between analysis parameters such as magnetizing field intensity and magnetizing frequency with coercivity, permeability and remnance.

An experimental study was undertaken to investigate the role of process parameters on grindability of medium carbon steel with particular emphasis on surface integrity. Grinding with miniature monolayer electroplated cBN wheels provided compressive residual stress throughout the experimental domain unlike conventional grinding. This can be attributed to desirable temperature control as the wheel takes away substantial part of grinding heat flux owing to its better thermal conductivity. Micromagnetic or Barkhausen Noise (BN) parameters correlated linearly with the residual stress indicating its applicability in assessing surface integrity of cBN ground products. Increase in maximum grit depth of cut (hm) provided more grain elongation and surface hardness due to more chip load during chip formation.

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.

Low carbon steel substrates have been grit blasted using alumina grits of various sizes under varying pressure, time, angle and standoff distances and the corresponding effect on surface roughness and surface residual stress has been studied. The mechanism of material removal in grit blasting has been analyzed. The effect of blasting process parameters on substrate surface residual stress has been studied using a statistically designed experiment. For this purpose the Barkhausen noise analysis (BNA) of the blasted surface has been undertaken. Then the BNA results have been calibrated against and complemented using the residual stress values measured using X-ray diffraction. The correlation between BN signal and the measured residual stress has been studied. The material removal in blasting takes place by microcutting, indentation or by a mixed mode depending on the blasting angle. During blasting the alumina grits themselves also undergo erosion. The analysis of the experimental results shows that the surface roughness increases with grit size, blasting pressure and to an extent with blasting time and blasting angle as well. The compressive residual stress of the surface and subsurface hardness increases with blasting pressure and blasting angle. The Barkhausen noise signal has a strong correlation with the magnitude of the compressive residual stress on the blasted surface.

An experimental investigation was carried out to study the effect of stresses that approach and exceed the yield point, on the magnetic properties of ground samples of medium carbon steel upon surface grinding. The observed magnetic behaviour included magnetic Barkhausen emission measurements, characteristics changes in the shape of hysteresis loop and magnetic properties derived from hysteresis loop. Relation between Barkhausen Noise (BN) parameters and other magnetic properties with stress have been discussed in term of degree of plastic deformation. It was observed that peak of BN signal, saturation magnetization and permeability derived from hysteresis loop depend to some extent on residual stress and degree of plastic deformation while other magnetic properties obtained from BN profile and hysteresis loop are stress insensitive. X-ray diffraction (XRD), metallographic study and microhardness measurement of ground samples have been undertaken to confirm the results obtained by analysis of magnetic parameters.