Hot tensile deformation behaviors and constitutive model of an Al–Zn–Mg–Cu alloy

A review on modelling techniques for formability prediction of sheet metal forming

Electroplated hard chromium (EPHC) is used in many industries as a wear and corrosion resistant coating. However, the long term viability of the electroplating process is at risk due to legislation regarding the toxic chemicals used. The physical vapour deposition (PVD) process has been shown to produce chromium and chromium-based coatings that could be a possible alternative for EPHC in some applications. This study investigates the microstructure and properties of two PVD chromium coatings as a possible alternative to EPHC to provide resistance to galling. Two PVD deposition processes are investigated, namely electron beam PVD (EBPVD) and unbalanced magnetron sputtering (UMS). Galling wear tests were performed according to ASTM G98-17. The results show that the two PVD coatings are of similar hardness, surface roughness and exhibit similar scratch behaviour. However, the galling wear resistance of the coating deposited by UMS is approximately ten times that of the EBPVD coating, and similar to that of the EPHC. X-ray diffraction reveals that the EBPVD chromium coating has a strong preferred orientation of the {200} planes parallel to the coating surface whilst in the UMS PVD coating, preferred orientations of the {110} and {211} planes parallel to the surface are observed. The EPHC does not exhibit relative peak intensities which conform to the International Centre for Diffraction Data (ICDD) powder diffraction pattern consistent with chromium. The crystal orientation of the PVD chromium coatings appears to play a significant role in influencing galling resistance.

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A comparison of the galling wear behaviour of PVD Cr and electroplated hard Cr thin films

Experiment research on rate-dependent constitutive model of Q420 steel

Active slip systems in bcc iron during nanoindentation: A molecular dynamics study

Tensile flow behavior of ultra low carbon, low carbon and micro alloyed steel sheets for auto application under low to intermediate strain rate

The purpose of this study is to develop a phenomenological model for prediction of the entire forming limit diagram from simple tensile material properties. The phenomenological model is based on the necking and ductile damage theories. In the proposed model, void nucleation is described as a function of the equivalent plastic strain, and void growth is a function of the stress triaxiality. The forming limit curves calculated from the proposed phenomenological model matched reasonably well in the region of uniaxial tension to balance biaxial tension with the experimental forming limit curves generated on C-Mn 440 steel, interstitial-free 340 steel, and interstitial-free steel sheets.

Prediction of entire forming limit diagram from simple tensile material properties

Formability is an important property requirement in sheet metal forming and mostly useful to automobile and aerospace industries. Every product design starts with finite element simulation before the die design and material selection stage. The forming limit curve along with finite element results acts as tool to investigate whether the design is feasible. Hence, it is of utmost importance that the forming limit curve is accurate over a wide range of strain path. Generally, a forming limit curve is derived from discrete failure strain points corresponding to different strain ratios by fitting a smooth curve. It has been observed from many studies that the generated forming limit curves are devoid of any failure points corresponding to equibiaxial strain path. This is found to be true even when the test conditions are supposed to produce biaxial state of strain. To understand the reason behind this observation, a set of forming limit diagram experiments and finite element analyses were carried out for high...

Effect of friction in stretch forming and its influence on the forming limit curve

While modelling single crystal deformation, often the hardening behaviour is approximated using a power law type hardening equation, the coefficients of which are determined by fitting predicted stress–strain curve to experimental stress–strain curve in the uniaxial tension. Also, in the literature, for BCC material either 24 or 48 slip systems have been considered with mixed conclusions. In this work, the suitability of such phenomenologically determined coefficients and the effect of using 24 and 48 slip systems on prediction capability for anisotropic hardening of an ultra low carbon interstitial free high strength steel observed during in-plane biaxial tension tests were assessed. It was found that, though there was some difference between the results for 24 and 48 slip systems, neither 24 nor 48 slip systems could predict the deformation behaviour accurately for all the cases considered.

Modelling anisotropic hardening of an ultra low carbon high strength steel using crystal plasticity

Light aluminium alloy piston is suitably reinforced at high load-bearing region with cast iron insert, and machining of such bimetallic material is more difficult with a single cutting tool material. Present study focuses on the orthogonal cutting of bimetallic material machining using cubic boron nitride as a cutting tool through finite element analysis. The effects of cutting parameters such as cutting velocity, feed rate and depth of cut on resultant cutting forces and the surface roughness were analysed. Those parameters yielding minimum cutting forces were identified as minimal cutting force parameters, so numerical simulation and experiments were carried out on these parameters. After machining, the intermediate bonding between metallic regions was studied using ultrasonic testing. Bimetallic machining is successfully simulated, and its potential is readily applied to an industrially important component.

G. Manikandan

Papers

Tensile flow behavior of ultra low carbon, low carbon and micro alloyed steel sheets for auto application under low to intermediate strain rate

Prediction of entire forming limit diagram from simple tensile material properties

Effect of friction in stretch forming and its influence on the forming limit curve

Modelling anisotropic hardening of an ultra low carbon high strength steel using crystal plasticity

Machining and simulation studies of bimetallic pistons