In the present research, similar and dissimilar resistance spot welding (RSW) process of St12 and galvanized steel sheets with thickness of 0.9 mm was investigated. The experiments were carried out based on the statistical design of experiments (DOE) approach to investigate the effect of RSW parameters on the welding quality, achieving the mathematical regression equations and predicting the new results. Welding time and electrode force were considered as the input process variables while the tensile-shear strength of the joints was considered as the process response. By comparing three RSW types, galvanized steel has the highest tensile-shear strength. Statistical analysis shows that tensile-shear strength is increased with increasing electrode force and welding time. Verification experiments for three types of RSW joints were carried out in order to analyse the obtained results via software. Good agreement between the verification tests and the optimization results revealed that the statistical modelling would be appropriate for RSW process. Welding time (T)  = 5 s and electrode force (P)  = 925 N, welding time (T) = 5 s and electrode force (P) = 1100 N and welding time (T) = 3 s and electrode force (P) = 925 N were obtained as the optimum settings for similar RSW of St12, dissimilar RSW of St12 to galvanized steel and similar RSW of galvanized steel, respectively. Manuscript profile

In this study EDM milling process parameters of AISI H13, have been investigated by using Response Surface Methodology (RSM). Current (16-32A), pulse-on time (100-700 µs) and depth of cut (1-3mm) were considered as independent variables, while surface roughness, tool wear ratio (TWR), and material removal rate (MRR) as process output responses. Results reveal that increases in the current and decreases in pulse-on time cause more MRR and more TWR and depth of cutting has no significant effect on them. Minimum surface roughness, minimum TWR and maximum MRR were considered as optimization criteria. Verification experiments were carried out in order to analyze the results via software. Optimized settings were used for EDM Milling and die sink EDM experiments to compare the results. The results indicate that using EDM milling has considerable economic savings than die sink EDM, better surface roughness, and higher MRR. Manuscript profile

This study is focused on investigating the parameters of laser percussion drilling process of nickel-base super alloy Inconel 718 with thickness of 1 mm. Fiber laser with the power of 500 watts was used as the laser source. Laser pulse frequency, duty cycle, laser power, focal point position, were assumed as the laser drilling process variables. The hole geometry features, i.e. entrance hole diameter, circularity of entrance hole, and hole taper were measured. The results indicated that pulse frequency of laser has a direct influence on the entrance hole diameter. Increasing the duty cycle leads to increases in hole taper. By increasing the laser power, entrance diameter and hole taper increases. Manuscript profile

Rene-80 nickel-base superalloy as an alloy for production of the jet turbine blades shows high mechanical properties as well as microstructure stability during the high temperature engine operation. In this research, age hardening heat treatment cycle was done on the as-cast Rene-80 superalloy. In the following, microstructure, elemental analysis of phases and macro-hardness of the alloy before and after of heat treatment were compared together with scanning electron microscopy (SEM) observation, X-ray spectrometry (EDS) and hardness test, respectively. The obtained results showed that γ’ carbide particles in the as-cast alloy had cubic morphology, while these particles showed more spherical morphology after heat treatment and also the amount of this phase was reduced after heat treatment. Based on hardness test results, hardness of as-cast sample was reduce from 38.17 to 35.01 HRC after age hardening heat treatment, which can be due to the reduction of carbide particles and their morphological modification. Manuscript profile

In this paper, a three-dimensional finite element model has been developed to simulate the laser-TIG hybrid welding (HLAW) of stainless steel 1.4418 with thickness of 4 mm. Transient temperature profile and dimensions of the fusion zone and heat affected zone (HAZ) during welding process are calculatedusing finite element method (FEM) and were solved in the ABAQUS/Standard software.The heat source model is a combination of Goldak distribution for the arc heat flux, a body Gaussian distribution for laser heat flux and a surface heat flux model. The DFLUX subroutine was used for implementation of the movable welding heat sources of the models.To validate the model, several HLAWexperiments were performed with a pulsed Nd:YAG laser and TIGsources. Good agreement between the simulated and the experimental measurements revealed that the model would be appropriate forHLAWnumericalsimulation. Among the material properties, the material conductivity is the most important term which influences on the weld bed dimensions. Manuscript profile