Resistance spot welding of a thin 0.7 mm EN10130: DC04 material onto a thicker 2.4 mm 817M40 engineering steel

The effects of welding current, electrode force, and welding time in a resistance spot weld were studied to investigate the effectiveness of welded joints between a thin EN10130: DC04 material and a thicker 817M40 part, through analysis of the microstructural and mechanical properties. All welded specimens were subjected to tensile testing at room temperature (25°C) and sub-zero temperature (-46°C) to test the strength of the welded joints. No full button failure was observed at either room temperature or sub-zero temperature after optimization of the weldng parameters. The fusion zone was observed to consist mainly of martensitic phase, due to rapid quenching, while the HAZ was composed of clusters of martensite in a ferrite and bainite matrix. The base 817M40 metal remained fully ferritic after welding. The hardness was found to increase with increasing welding current. An increase in nugget size, indicating good fusion of the weld, was observed with an increase in the welding current.

Optimization of Parameters and Prediction of Response Values Using Regression and ANN Model in Resistance Spot Welding of 17-4 Precipitation Hardened Stainless Steel

17-4[Formula: see text]PH steel, also known as UNS 17400 steel or called SAE type 630 stainless steel, is a very important category of steel which has tremendous and extraordinary properties. The superior properties include high corrosion resistance, high hardness and high strength due to the conversion or phase change of the austenite to martensite by cooling the material to room temperature after heating to a temperature around 1030[Formula: see text]C. Normally, this procedure is called as precipitation hardening and hence the name. Due to its extensive properties, the 17-4[Formula: see text]PH steel finds its applications in a variety of industries including pump shafts, oil path, mechanical seals, and within the aerospace industry, parts of the aircrafts, chemical industries and petroleum industries. When a material is used in any kind of applications, fastening is the major process involved. Hence, there should be a standard welding procedure involved in generating a permanent fastening. In this work, resistant spot welding is considered as the welding process and the major parameters are considered which have a crucial effect on the whole process. The responses are considered to be the nugget diameter and tensile strength which denote the weld quality majorly. The process parameters with the help of literature are considered and they are electrode force, voltage and weld current. Taguchi method is used to design the experiments along with the NN tool to generate and predict the new response values. The results show that the major affecting factor is electrode force followed by current and then the voltage. Comparison is done to choose a better model for predicting the optimum responses with the given values of the input parameters. The results are pretty much accurate for both but still the regression model yields better results and almost similar values to the experimental values. Therefore, better results can also be obtained by ANN model by continuous training of the model.

Investigation of Dissimilar Resistance Spot Welding Process of AISI 304 and AISI 1060 Steels with TLBO-ANFIS and Sensitivity Analysis

In this work, the process of dissimilar resistance spot welding (RSW) for AISI 304 and AISI 1060 steel sheets is experimentally investigated. The effects of the main process parameters such as welding current, electrode force, welding cycle, and cooling cycle on the tensile-shear strength (TSS) of dissimilar RSW joints are studied. To this aim, using a central composite experimental design based on response surface methodology (RSM), the experimental tests were performed. Furthermore, from the test results, an adaptive neuro-fuzzy inference system (ANFIS) was developed to model and estimate the TSS. The optimal parameters of the ANFIS system were obtained using a teaching-learning-based optimization (TLBO) algorithm. In order to model the process behavior, the results of experiments were used for the training (70% of the data) and testing (30% of the data) of the adaptive inference system. The accuracy of the obtained model was investigated via different plots and statistical criteria including root mean square error, correlation coefficient, and mean absolute percentage error. The findings show that the ANFIS network successfully predicts the TSS. In addition, the network error in estimating the TSS in the training and test section is equal to 0.08% and 5.87%, respectively. After modeling with TLBO-ANFIS, the effect of each input parameter on TSS of the dissimilar joints is quantitatively measured using the Sobol sensitivity analysis method. The results show that increasing in welding current and welding cycle leads to an increase in the TSS of joints. It is concluded that TSS decreases with increases in the electrode force and cooling cycle.

Resistance Spot Welding of Dissimilar Alloys 1008 Low Carbon Steel- 1100 Aluminum Alloy

The resistance spot welding is adopted to joint dissimilar alloys such as aluminum alloy 1100 , and low carbon steel alloy 1008 by using cover plate. This study aims to optimization the best conditions of dissimilar welding of Aluminum with low carbon steel by RSW, and improving the properties of joints by many method. three different variables were used for the welding process: welding current (5, 6 ,7 and 8 KA), weld time (0.5, 1 and 1.5 sec) and electrode force (13.2 and 15.5 N).The welding joints are ―examined by a scanning electron microscope SEM and a X-ray diffraction‖ for the purpose of discussing the causes of the improved characteristics. The results revealed that the best welding conditions were under welding current 7 KA , weld time 1 sec and electrode force 13.2 KN, where the joint possessed the maximum shear force (4.8KN) and after improvement the tensile shear force become (6.02 KN), in addition to presence of the intermetallic compounds at optimum condition , such as AlFe3,Al5Fe4 and Al13Fe4, in the joint layer between dissimilar metal improves of the tensile shear forces and hardness in fusion zone.

Expulsion investigation and fracture characteristics in spot welded advanced high strength auto steels

Increased use of advanced high strength steels in resistance spot welding (RSW) is necessary for manufacturing safe and affordable vehicles. Unfortunately, the investigation of expulsion monitoring and control of advanced high strength steels (AHSS) is limited. A data acquisition system was designed for monitoring weld expulsion via the measurement of voltage, current, dynamic resistance, electrode force and displacement. Three control strategies were proposed on the basis of the rate of change in the dynamic resistance, the electrode force and the electrode displacement. Micro-hardness tests, tensile shear tests and fatigue tests were carried out. The expulsion effects on the mechanical properties, fracture modes, and metallurgical features were investigated using optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Fatigue crack initiation locations were also observed, which were verified by the theorectical stress analysis. In addition, the causes of interfacial fracture were discussed in relation to weld parameters.

Expulsion investigation and fracture characteristics in spot welded advanced high strength auto steels

Increased use of advanced high strength steels in resistance spot welding (RSW) is necessary for manufacturing safe and affordable vehicles. Unfortunately, the investigation of expulsion monitoring and control of advanced high strength steels (AHSS) is limited. A data acquisition system was designed for monitoring weld expulsion via the measurement of voltage, current, dynamic resistance, electrode force and displacement. Three control strategies were proposed on the basis of the rate of change in the dynamic resistance, the electrode force and the electrode displacement. Micro-hardness tests, tensile shear tests and fatigue tests were carried out. The expulsion effects on the mechanical properties, fracture modes, and metallurgical features were investigated using optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Fatigue crack initiation locations were also observed, which were verified by the theorectical stress analysis. In addition, the causes of interfacial fracture were discussed in relation to weld parameters.

Microstructure Investigation, Hot Tensile and Hot Corrosion of IN600 to Nimonic 75 heterogeneous Connection in Spot Welding

Nimonic 75 and Inconel 600 alloys are the Nickel-based superalloys which are used in manufacturing gas turbine components. In the current research, a superalloy Ni-based Nimonic sheet and Inconel 600 were used, joint by resistant spot welded (RSW) machine at currents of 2, 4, and 6 kA, pressure of 5 and 7 bar, and times of 0.6, 0.9 and 1.2. Non- destructive inception methods and light and scanning electron method (SEM) and light optic microscope (LOM) were used to evaluate joints' quality. Shear and micro-hardness test was used to check the mechanical properties of the joint. The findings indicate that the most appropriate welding connection of inhomogeneous points at the current of 4 kA was the holding time 0.9 second and electrode force 7bar. The analysis of microstructure consisted of 3 welding zones which are affected by heat and the base metal. The warm corrosion scanning microscope test results at 600 °C and 800 hours confirmed that the existence of a chromium oxide layer on the surface of the superalloy, which has the main role in protecting the piece in the output temperature.

The Effect of Welding Current and Electrode Force on the Heat Input, Weld Diameter, and Physical and Mechanical Properties of SS316L/Ti6Al4V Dissimilar Resistance Spot Welding with Aluminum Interlayer

Welding parameters obviously determine the joint quality during the resistance spot welding process. This study aimed to investigate the effect of welding current and electrode force on the heat input and the physical and mechanical properties of a SS316L and Ti6Al4V joint with an aluminum interlayer. The weld current values used in this study were 11, 12, and 13 kA, while the electrode force values were 3, 4, and 5 kN. Welding time and holding time remained constant at 30 cycles. The study revealed that, as the welding current and electrode force increased, the generated heat input increased significantly. The highest tensile-shear load was recorded at 8.71 kN using 11 kA of weld current and 3 kN of electrode force. The physical properties examined the formation of a brittle fracture and several weld defects on the high current welded joint. The increase in weld current also increased the weld diameter. The microstructure analysis revealed no phase transformation on the SS316L interface; instead, the significant grain growth occurred. The phase transformation has occurred on the Ti6Al4V interface. The intermetallic compound layer was also investigated in detail using the EDX (Energy Dispersive X-Ray) and XRD (X-Ray Diffraction) analyses. It was also found that both stainless steel and titanium alloy have their own fusion zone, which is indicated by the highest microhardness value.

Small-scale resistance seam welding of 304 stainless steel with capacitor discharge welding machine

In this paper, small scale resistance seam welding (SSRSEW) of 304 stainless steel sheet with a thickness of 0.1 mm with a capacitor discharge (CD) welding machine is investigated. The effect of the main parameters such as discharged energy, electrode force, and electrode speed on the quality of the weld seam was investigated. In order to control the speed of the electrode, the electrode wheel was mounted on a CNC machine. Mechanical tests such as tensile-shear and peel tests were used to evaluate the quality of the weld seam. Also, the failure modes were investigated in different welding conditions. The results show that the discharged energy has more effect on the weld seam strength and the maximum strength in the peel test is usually lower than the strength of the tensile-shear test. Also, discharge energy level of 14 ws and electrode force of 20 N and electrode speeds of 200 and 300 mm/min are the optimum welding condition for welding the 304 stainless steel sheets with a thickness of 0.1 mm.

Resistance Welding of Aluminium Alloys with an Electromechanical Electrode Force System

The idea presented in this chapter is an innovative welding machine electrode force system. The operation, advantages of the new solution and the optimisation of the welding process were illustrated by the welding of aluminium bars (5182) (ø 4 mm). The solution involves controlling the force and/or displacement of welding machine electrodes. The modulation of electrode force significantly improves welding, particularly as regards aluminium alloys (requiring a very short welding process). The tests involved the numerical analysis of two electrode force systems, i.e. a conventional Pneumatic Force System (PFS) and an Electromechanical (Servomechanical Force) System (EFS). The numerical tests were performed using SORPAS software. FEM calculation results were verified experimentally. The technological welding tests were conducted using inverter welding machines (1 kHz) equipped with various electrode force systems. The research included metallographic and strength (peeling) tests and measurements of characteristic parameters. The welding process optimisation based on the EFS and the hybrid algorithm of force control resulted in i) more favourable space distribution of welding power, ii) energy concentration in the central weld zone, iii) favourable melting of the material within the entire weld transcrystallisation zone, iv) obtainment of the full weld nugget and v) longer weld nugget diameter.