Variation Of Welding Parameters Research Articles

Effects of Parametric Variations on Bead Width of Gas Tungsten Arc Welding of AISI 1020 Low Carbon Steel Plate

Variations of welding parameters and their effects on weld bead width of gas Tungsten Arc Weldment of 10 mm (thickness) AISI 1020 low carbon steel plate was investigated in this paper. Welding experimentation was carried out for Twenty seven (27) runs with three (3) ranges of current (120A, 150A and 190A), three (3) ranges of voltage (19V, 21V and 25V) and three (3) ranges of gas flow rate (13, 15 and 18 L/min) respectively. Applying the same range of parameters as inputs in Solid Works 2017 version, Finite Element Method (FEM) was employed to predict the weld bead width variations. To avoid wider weld bead width which can contribute to poor weld quality, a condition was established, in which the bead width values from both experimental and FEM prediction must not exceed 1.25 mm. Thermal transient flow simulation was also carried out with Solid Works 2017 version to determine the melting behavior of the material which revealed 1694 K as the solidus temperature and 1738 K as the liquidus temperature. It was observed that varying the welding current, arc voltage and the gas flow rate for the welding experimentation and finite element simulation, alternating weld bead widths of close proximity were produced. However, certain sets of parameters used for the welding experimentation met the aforementioned condition (≤1.25 mm) with the following values 1.02 mm, 1.05 mm, 1.10 mm, 1.07 mm, 1.15 mm and 1.19 mm while the same combination of parameters in the FEM met the condition with the following FEM predicted values 1.0 mm, 1.03 mm, 1.08 mm, 1.05 mm, 1.13 mm and 1.15 mm respectively. These findings are only applicable to AISI 1020 low carbon steel, therefore, melting point of materials should be adequately understood with proper knowledge of welding parameters prior to commencement of welding operation to avoid excessive increase in weld bead width.

A study on welding quality for the automatic vertical-position welding process based on Mahalanobis Distance method

Purpose: The welding quality and reducing production cost could be achieved by developing the automatic on-line welding quality monitoring system. However, investigation of welding fault to quantify the welding quality on the horizontal-position welding has been concentrated. Therefore, MD (Mahalanobis Distance) method on the vertical-position welding process by analysing the transform arc voltage and welding current gained from the on-line monitoring system has been applied. Design/methodology/approach: The transformed welding current and arc voltage data were taken from the experiment whereby the data number was 2500 data/s. The prediction of Contact Tip to Work Distance (CTWD) to gain best welding quality using the waveform variations were then taken from the experimental results. MD was employed to quantify the welding quality by analysing the transformed arc voltage and welding current. Finally, the optimal CTWD setting has verified the developed algorithms through additional experiments. Two kinds of experiments has been carried out by changing welding parameters artificially to verify the sensitivity and feasibility of WQ (Welding Quality) based on the concepts of MD and normal distribution. Findings: The results represented that WQ was fully capable of quantifying and qualifying the welding faults for automatic vertical-position welding process. Research limitations/implications: The arc welding process on the vertical-position compared to a horizontal-position welding is much more difficult because the metal transfer is influenced by the gravity force. To solve the problem, a new algorithm to monitor and control the welding fault during the arc welding process has been developed. Furthermore, optimization of welding parameters for the vertical-position welding process was really difficult to use the developed algorithms because they are only useful in selecting stored data and not for evaluating the effect of the variation of welding parameters on the weld ability. Practical implications: The developed algorithm could be achieved the highest welding quality at 15mm CTWD setting which the welding quality is 99.50% for the start section and 99.68% at the middle section. Originality/value: This paper proposed a new algorithm which employed the concepts of MD (Mahalanobis Distance) and normal distribution to describe a good quality welding.

Friction stir spot welding ABS using triflute-pin tool: Effect of process parameters on joint morphology, dimension and mechanical property

A triflute-pin tool and a clamping plate with a circular hole were utilized to friction stir spot weld acrylonitrile butadiene styrene sheets. The influences of rotational speed, plunge depth and dwell time on the joint morphology, dimension and mechanical performance were investigated. Joint micromorphology was analyzed by the optical microscope and lap-shear tensile tests were conducted to assess the joint quality. Results showed that excessive rotational speed and plunge depth resulted in linearly distributed pores and gaps, and long dwell time caused the formation of cavities. With the increase of rotational speed, bonded area diameter increased first and then decreased. Plunge depth slightly affected joint dimension while dwell time had a positive effect on it. Four failure modes, namely shear fracture, pull lower nugget, pull upper nugget and the mixed shear and pull nugget, were observed in the tests. The fracture load of the joints varied significantly with the variation of welding parameters. Joints produced with the least tool stirring showed the maximum shear strength of 20.7 MPa, which was 92.8% of the base material. In addition, triflute pin was advantageous to produce joints with higher strength than the cylindrical pin.

Resistance Spot Welds of 304I Austenitic Stainless Steel, Part 1:Fundamental, Simulation, Weld Growth, Tensile Strength And Failure Mode Analysis

Austenitic stainless steel(ASS) is very common material that used in many industries today. Suitable joining method should be of low cost; reliable and long life. In such situation, the industries may prefer to use the resistance spot welding (RSW) for such ASS sheet. The weld quality of RSW joint is usually considered by nugget size which relies on the welding parameters. This paper analyzes the weld nuggets' characteristic of 304L austenitic stainless steel with relevant to its basic welding parameters (current, weld time and force). The entire experiment is carried out by varying the welding current and welding time at first attempt and the welding current and electrode force at second attempt. The increment of current and weld time has resulted proportional increment of nugget diameters; whereas the force increment has resulted reduction of nugget diameters. These results have been relatively compared with simulation results for the proper weld region identification. Eventually the welded joints were characterised by tensile shear test, macro graph and elongation measurement to relate the changes that happened due to the variations of welding parameters.

Experimental study of friction taper plug welding for low alloy structure steel: Welding process, defects, microstructures and mechanical properties

A research investigation has been undertaken to identify the various stages and variation of welding parameters in friction taper plug welding (FTPW) process and to explore their effects on the performance and properties of the welds. According to the variation of axial force, the overall FTPW process is divided into feeding phase, pressing phase, welding phase, and forging phase. The rotating speed, welding force, and burn-off rate remain nearly constant in welding phase. However, the torque peaks in welding phase when after few seconds of welding force setting is reached. Rising the welding force would increase the peak torque, welding torque, and burn-off rate, but decrease the welding time. When improper welding parameter is used lack of bonding and incomplete filling defects would form within the weld. The microstructure of the weld metal is consist of retained austenite, pearlite, and various Widmanstätten ferrite. In heat affect zone, it is mainly of lathy upper bainite. Defect free welds exhibit favorable tensile properties of which 548.3MPa tensile strength and 27.5% elongation that equal to the base metal could be found.

Effect of the Heat Input in the Mechanical and Metallurgical Properties of Welds on AHSS Transformed Induced Plasticity Steel Joined with GMAW Processes in the Automotive Industry

ABSTRACTThe effect of the heat input on the mechanical and metallurgical properties of the welds has been investigated in the heat affected zone (HAZ) of welds joined with gas metal arc welding (GMAW), using normal production welding parameters. The thermal effect in the HAZ of the welds is important for the optimization of the welding parameters used when weld transformed induced plasticity (TRIP) steels, because this will have a great influence in the mechanical and metallurgical properties of the weld. In this work 3 samples was welded a high, average and low heat input, with the variation of welding parameters to obtain different thermal affectation to investigate the variations in different parts of weld joint: weld, HAZ and base metal, due the heat applied for the welding process used. Mechanical properties were evaluated by tension test, microhardness and fatigue testing and metallurgical evaluation with optical metallograpy, scanning electron microscopy (SEM), fractograpy and X-Ray diffraction (XRD).The results obtained shows that the mechanical properties of the tension test decrease when the heat input increase and the microhardness exhibit a softening zone in the HAZ with lower hardness and the fatigue life were similar for all heat inputs for the high stress levels, but only in low stress there is a difference. For metallurgical properties the metallographic evaluation shows ferrite, bainite - martensite and retained austenite, and the fractography analysis exhibit a ductile fracture in all cases and the content in volume fraction of retained austenite increases in the HAZ of welds when increasing heat input in to the base metal due the thermal effect.

ANALYSIS OF THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF DUAL PHASE STEEL UNDER THE EFFECTS OF DIFFERENT BRAZING RATES

ABSTRACTEnvironmental, concerns regarding reducing CO2 emissions and the drive of having better fuel economy have already enthused the car manufacturer to use the weight materials having better mechanical properties. Automotive industry has shown a great interest in Dual Phase steels due to the possibility of reducing weight of vehicles and increasing the passenger safety at a very competitive cost. Automotive applications unavoidably entail welding and joining in the manufacturing process and the fatigue resistance of welded joints due to the integrity and safety requirements. The variation of welding parameters (voltage, current and speed of welding) affects weld performance, mechanical, and metallurgical properties.The CMT (Cold Metal Transfer) braze welding is a relatively new technology that partially decouples the arc electrical transients from the filler wire feed rate. It allows reducing the heat required for welding and permits higher joining speeds.The aim of this work is to study the interfacial microstructures and intermetallic compounds produced by cold metal transfer welding of two plates of galvanized DP600 dual phase steel with CuSi3 as filler metal. The study was performed by applying a CMT braze welding with three different joining speeds. The welded microstructures and microhardness were determined and related to the welding process conditions.A small HAZ, constituted by martensite, bainite and coarse ferrite grains, has been highlighted. Furthermore, an intermetallic Fe-Si-Cu compound layer formed at the interface between steel and filler metal. The joining speed sways the size of ZTA since the heat input Q affects the phase transformation in the weld and heat affected zoneThis parameter also affects the thickness of the compound layer and the size of precipitates in the filler metal, likewise the mechanical characteristics. The fracture starts at the interface steel-copper where intermetallic compounds formed.

Real Time Monitoring Weld Quality of Resistance Spot Welding for Stainless Steel

Resistance spot welding (RSW) is one of the most widely used processes in sheet metal fabrication. Although used in mass production for several decades, RSW has a major problem of inconsistent quality from weld to weld, which results from both the complexity of basic process as well as from various process conditions, noise and errors. There have been a number of investigations on monitoring and controlling the resistance spot welding of low carbon steel by using dynamic resistance, but those for stainless steel are limited because the dynamic resistance has descent property. Dynamic resistance curve in spot welding for low carbon steel has a typical shape: the resistance drops sharply at the beginning, and then rises; before the current is terminated, the resistance starts to drop, which results in a peak. Unlike low carbon steel, dynamic resistance for stainless steel decreases rapidly at the beginning and then decreases at a reducing rate.The objective of this research is to explore the effects of various process conditions in spot welded stainless steel on quality by using dynamic resistance. The process conditions studied in this research are chosen to be the most often observed in production, such as variations of welding parameters, edge weld, small weld spacing, poor fitup and axial misalignment. A series of experiments will be conducted to research how process conditions affect the dynamic resistance. The results show that dynamic resistance responds well to the variations of process conditions and can serve as an important indicator of weld quality.