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.

INFLUENCE OF THE CHEMICAL COMPOSITION AND METHOD OF SMELTING ON THE PROPERTIES OF THE METAL OF WELDED JOINTS OF ECONOMICALLY ALLOYED CHROMIUM-MANGANESE-NICKEL STEELS

The results of studies on the influence of the chemical composition on mechanical properties of the base metal and the metal of the near-seam zone of welded joints of ferrite-austenitic steels are presented. The positive effect of microalloying of steels with calcium and cerium on the resistance to embrittlement of the metal after exposure to the thermal welding cycle is shown. It is established that alloying ferrite-austenitic steels with molybdenum and vanadium reduces the tendency to grain growth during welding heating, and doping with nitrogen leads to the stabilization of the phase composition of steels under the influence of elevated welding and operating temperatures.

An intelligent Model for Defect Prediction in Spot Welding

There are more than 30% defect in the spot welding of cars and randomly chosen cars are performed ultrasound or destructive testing. This makes the process very vulnerable and unpredictable. This results in huge reworks, productivity, monetary loss and negative impact on brand name. This research paper presents the prediction of defect using machine learning models and as well forecasting models in spot welding through optimized methodology. This defect prediction model is useful in determining the defects that are likely to occur during spot welding. The forecasting model for process parameters data pattern, trends, etc. helps to identify the link between predicted defects. This model can evolve and improve over time by considering data from previous phases and history data of the spot welding cycle. Predicting the defects before testing begins improves the quality of the product being delivered and helps in planning and decision making for future spot welding. The optimized defect prediction methodology in spot welding reduces the defects and predicted sample for testing which reduces the rework and increase the productivity, monetary value and brand name. The experimental result shows that the spot-welding methodology has shown improvement over existing spot-welding method. Please see the six-sigma (Fig:13) chart for before and after improvement curve and value.

The Effect of Preheating and Non-Preheating in Cast Iron Welding Toward Mechanical Properties

Cast iron material is a material that has brittle properties and is less able to withstand stress due to the welding cycle caused by flake graphite in cast iron. Because of these problems, in connecting cast iron materials using the SMAW welding method, it is necessary to have heat treatment (preheating) to avoid the welding problems on the properties of cast iron. The purpose of this study is to determine the effect of heating and non-heating on the cast iron before the welding process. Therefore, this research will play a crucial contribution as a reference for cast iron welding researchers and cast iron welding process. The method of the research was experimental research, where the measurement results were obtained directly from the specimens. The welding was using an open V seam. The specimen used was cast iron with a thickness of 8 mm. One cast iron was given heat treatment at a temperature of 260ºC and the others did not receive heat treatment before being welded. The welding process used SMAW with CIN - 2 electrodes with a diameter of 3 mm. The test used the bending test on the face specimens according to the American Welding Society D1.1 standard. The results showed that there was an effect of the preheating treatment on cast iron, which that the non-preheating specimens were easier to fracture than the preheating specimens. Thus, it can be concluded that welding with preheating is better than welding without preheating.

Assessment and Optimization of a Clean and Healthier Fusion Welding Procedure for Rebar in Building Structures

The welding procedure for reinforcing bars used in reinforced concrete takes place at fixed industrial installations. The welders must ensure that the reinforcing bar positions are maintained throughout all stages leading up to concreting. Fusion welding offers an alternative procedure that entails fewer risks for the workers’ health. In this study, we aimed to determine the minimum parameters for the intensity, pressure, and time necessary to ensure the level of performance required by this assembly welding. A total of 2160 joints were manufactured, comprising the different thicknesses. For each thickness measurement, 45 different combinations of parameters were applied. The joints were evaluated based on the resulting dimensions and on the failure force necessary to break the joint. For different thicknesses, the breaking loads were over 7350 N. In addition, the welding cycle times did not exceed three seconds. Based on the results obtained in this study, we concluded that assembling rebar (manufacturing reinforcing bars) by electrical resistance welding is a viable option. This method is fast, safe, and clean, and reduces the risks to the workers’ health.

STRUCTURE OF HIGH-CARBON STEEL AFTER WELDING WITH RAPID COOLING

<p class="AMSmaintext1">In this paper the effect of rapid cooling during arc welding on the structure of fusion layer and heat affected zone (HAZ) of high-carbon low alloyed steel have been studied. The main idea was that despite of high carbon content (1.2%) it is necessary to achieve quenching in HAZ. Due to proper chemical composition of welded steel martensite start temperature Ms is about 20 ^oC, therefore austenitic structure of quenched metal is preserved after rapid cooling. Exposition of HAZ to excessive heat during welding cycle leads to local precipitation of carbides from austenite and thus raising of Ms. In this case some amount of martensite was present in structure after cooling along with austenite and carbides. Microstructure, microhardness and chemical composition of remelted electrode metal, fusion zone and HAZ were studied by means of optical microscopy, SEM, EDX and microhardness testing.</p>

Conditions of Possible Application of Vibration Processing in the Course of Welding

Enough works in which positive action of the vibration fluctuations imposed both in the course of welding of a design and after it is specified are known. In the article features of influence of low-frequency vibration fluctuations in the course of a welding cycle on properties of welded connections from steel A 516-55 are considered. The conducted pilot studies of influence of vibration influence of a welding bathtub in the course of welding on structure and physico-mechanical properties of metal of welded connections have allowed to prove positive action of this technology which leads to increase in durability and fatigue endurance of welded connections. This fact will allow to expand using of technology of vibration processing in the course of welding for production of the welded equipment of various type.

Numerical-experimental validation of the welding thermal cycle carried out with the MIG welding process on a 6063-T5 aluminium tubular profile

The purpose of this work is to validate the thermal welding cycle obtained experimentally with the metal inert gas (MIG) welding process on a 6063-T5 aluminium tubular profile using the finite element method. The assembly formed by the tubular profile and the weld bead obtained experimentally is represented in an accurate way, taking care of both the geometry and the contour of the weld bead. The precision achieved in the numerical-experimental validation carried out by means of the finite element method is due to the care that has been taken in drawing the welded piece together with the weld bead made experimentally. In the validation carried out, the experimental and numerical cooling curves and the critical cooling time between 400 and 300?C (t4/3 ) in both curves are compared.