Welding Of AISI Research Articles

Influence of Heating Stage Parameters on the Joint Strength of Rotary Friction Welded AISI 1045 and AISI 304 Steels: A Polynomial Model

Rotary friction welding (RFW) result is much affected by heating and joining stage parameters. Heating stage is the period where friction takes place to generate heat at the interface. Parameters that alter the heating are friction pressure, friction time and rotation speed. In this work, experiment of RFW AISI 1045 and AISI 304 under different friction pressure and friction time was carried out. The objective was to investigate the relation between those parameters with the welding strength. The experiments were performed using one-factor-at-a-time (OFAT) strategy. A polynomial model of relation between joint strength with friction pressure and friction time was developed. Welding efficiency of 81.7% from the AISI 304 base metal was attained. Optimum setting friction pressure of under constant friction time was 40 bar, whereas the optimum setting friction time under constant friction pressure was 5 seconds.

Influence of degree of deformation on welding pore reduction in high-carbon steels

Locally adapted properties within a machine component offer opportunities to increase the performance of a component by using high strenght materials where they are needed. The economic production of such hybrid components on the other hand represents a major challenge. The new tailored forming process chain, which is developed within the collaborative research center (CRC 1153) represents a possible solution to produce hybrid components. This is made possible by the use of pre-joined hybrid semi-finished products made from two different steel alloys, which are subsequently formed. The semi-finished products can be manufactured for example by means of deposition welding. Due to a thermal mechanical treatment, an overall higher component strength of the joining zone can be achieved. The deposition welding processes can be used to generate a cladding on a base material. During the welding, one of the most difficult tasks is to reduce the amount and size of pores in the joining zone. These pores can reduce the strength in the joining zone of the welded parts. However, additional pores can occur in the intermediate zone between the substrate and the cladding. In the presented study, the influence of the forming process on the closing of pores in the cladding and in the intermediate zone was investigated. Therefore, cylindrical specimen were extracted in longitudinal direction of the welding track by wire-cut eroding. These welding tracks are manufactured by plasma-transferred arc welding of AISI 52100 on a base plate made of AISI 1015. Further, specimens were prepared transversely, so that the base material, the intermediate layer, and the welded material are axially arranged in the specimen. The prepared specimen were checked for pores by means of scanning acoustic microscopy. Subsequently, an uniaxial compression test was carried out with various degrees of deformation and the two specimen designs were examined again for pores. A microstructure analysis was carried out after each step. The investigations show that there is a need for a minimum degree of deformation to reduce pores in the welded material. However, this required plastic strain cannot be achieved in the welded material of the hybrid specimen, which is a result of the homogeneous temperature distribution in the specimen. The homogeneous temperature distribution leads to different flow properties in the specimen, which means that the main plastic deformation is taking place in the base material.

CO2 laser spot welding of thin sheets AISI 321 austenitic stainless steel

Purpose: The present work aims to investigate the influence of CO2 laser spot welding (LSW) parameters on welding profile and mechanical properties of lap joint of AISI 321 thin sheet metals, and analyze the welding profile numerically by finite element (FE) method. Design/methodology/approach: The weld carried out using 150 W CO2 continues wave laser system. The impact of exposure time and laser power on the welding profile was investigated using an optical microscope. Microhardness and tensile strength tests were used to evaluate the mechanical properties of the joint. Ansys software was utilized to simulate the welding profile numerically. Findings: The results revealed that 2 s exposure time and 50 W power have led to uniform welding profile and highest shear force (340 N), lower hardness gradient across the heat affected zone (HAZ) and fusion zone (FZ). Finite element (FE) analysis of the welding profile showed good agreement with experimental analysis. Research limitations/implications: The selection of laser spot welding parameters for thin sheet metal was critical due to the probability of metal vaporisation with extra heat input during welding. Practical implications: Laser welding of AISI 321 steel is used in multiple industrial sectors such as power plants, petroleum refinement stations, pharmaceutical industry, and households. Thus, selecting the best welding parameters ensures high-quality joint. Originality/value: The use of CO2 laser in continuous wave (CW) mode instead of pulse mode for spot welding of thin sheet metal of AISI 321 austenitic stainless steel consider a real challenge because of the difficulty of control the heat input via proper selection of the welding parameters in order to not burn the processed target. Besides, the maintenance is easier and operation cost is lower in continuous CO2 than pulse mode.

Prediction of effects of process parameters and thermo-mechanical simulation of GMAW process for welding of AISI 430 steel

The present study is focused on welding of AISI 430 steel using AISI 309L wire rod using gas metal arc welding process. The welding voltage, welding speed, wire feed rate and gas flow rate are considered as input process parameters and their ranges are found out for good appearance of weld bead. The experiments are conducted using central composite design matrix and weld bead geometry parameters like bead height, bead width and bead penetration and mechanical properties like tensile strength and hardness are measured. The mathematical models for bead geometry parameters and mechanical properties are developed and the adequacy is checked using analysis of variance. The effects of process parameters on the bead geometry parameters, mechanical properties and microstructure are found out. The thermo-mechanical simulation is carried out using ANSYS simulation software to predict the temperature and stresses distribution in the weldment.

Prediction of effects of process parameters and thermo-mechanical simulation of GMAW process for welding of AISI 430 steel

Prediction of effects of process parameters and thermo-mechanical simulation of GMAW process for welding of AISI 430 steel

Temperature and Time Dependent Analysis of Tungsten Inert Gas Welding of Low Carbon Steel Plate using Goldak Model Heat Source

In this study, temperature and time dependence analysis was carried out on Tungsten Inert Gas (TIG) Welding of AISI 1020 Low Carbon Steel Plate of 10 mm thickness. The TIG welding parameters deduced from design of experiment for current ranging from 96-213 A, voltage ranging from 16-25 V and gas flow rate ranging from 11-19 L/min was used as input variables for the welding experimentation and simulation using Finite Element Method (FEM) based on Goldak model heat source. There was proximity in the regression plot of temperature outputs for both the experimental and FEM predicted values. The temperature and time dependence transient thermal analysis was simulated for 20 seconds at welding speed of 1.5 mm/s in steps of 2.5 seconds for each heat source and the result revealed that at each increasing step, the heat distribution characterized by intense heat, phase transformation and alteration in mechanical properties gradually formed a spiral transient patterns from the weldment known as Heat Affected Zone (HAZ). Hence the longer the arc heat at a given weldment the wider the HAZ which result in high Keywords: Welding, Temperature, Time, Welding current, Heat distribution, Flat plate

Experimental Analysis of Corrosive Impact of Oxidizing and Non-oxidizing Environment on Sensitized Welded and Unwelded Samples of AISI 316

An experimental analysis was carried out to investigate the corrosivity of sensitized welded and unwelded austenitic stainless steel AISI 316, in oxidizing (H₂SO</sub>4</sub>) and non-oxidizing (HCL) media. The selected samples were cut into several equal pieces. To induce sensitization, the samples were heated and soaked at 750°C at different soaking time intervals such as 30 minutes, 60 minutes, 180minutes, 300 minutes and 600 minutes followed by water quenching. The sensitized welded and unwelded samples each were subjected to immersion duration test in the oxidizing and non-oxidizing media for 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 minutes, respectively. It was concluded from the results obtained that corrosion rate of welded and unwelded decreases as soaking time and immersion duration increases at constant soaking temperature, in non-oxidizing medium of hydroChloric acid (HCL); but the decrease in corrosion rate is more in the unwelded samples. In the oxidizing medium of sulphoric acid (H₂SO</sub>4</sub>); corrosion rate of the samples decreased as immersion duration/soaking time increases. However, the welded samples experienced erratic behaviour in the oxidizing medium, having a lower corrosion rate than their unwelded counterpart surprisingly, at immersion duration between 25-50 minutes as soaking time increases at constant soaking temperature of 750°C.

Enhancing the Fatigue Properties of Friction Welded AISI 1020 Grade Steel Joints using Post Weld Heat Treatment Process in Optimized Condition

Abstract Fatigue life is the most important criteria in each and every areas subjected to loading. The prediction of fatigue life is essential in the field of engineering sciences and it only defines the quality and life time of the materials subjected to loading. Therefore, the ultimate aim of this research work article is to predict the fatigue life of friction welded AISI 1020 grade low carbon steel joints before and after Post Weld Heat Treatment (PWHT) process for which the welding parameters have been optimized by Response Surface Methodology (RSM) as per ANOVA design matrix in order to obtain the maximum strength in the joints. The different size of the grains encountered due to the variation of temperature, pressure and solidification at various zones during the process before and after the post weld heat treatment in As-welded and post welded conditions were analyzed using an optical microscope. The microstructural features and the fracture surfaces of friction welded AISI 1020 grade steel joint using optimized parameters with parent metal microstructure are compared and analyzed.

Induction Pre-Heated Linear Friction Welding

A two-level factorial design of experiments (DOE) approach is used to study the effect of four factors (average rubbing velocity, weld pressure, burn-off distance, and preheat temperature) on two response variables (weld strength and energy input) for the induction heating and linear friction welding of AISI 1020 steel. Weld strength, as analyzed though three-point bending, was insensitive to all four of the design factors. Pressure, upset, and velocity show statistically significant inverse, linear, and linear relationships with energy used, respectively. Pressure has the largest effect on energy used, followed by velocity and upset.

Investigation on Weld Pool Dynamics in Laser Welding of AISI 304 Stainless Steel With an Interface Gap Via a Three-Dimensional Dynamic Model and Experiments

This paper reports on numerical and experimental investigations involving examination of the effects of an interfacial gap in the range of 0–0.3 mm on keyhole and molten pool dynamics. A numerical model was developed to investigate the three-dimensional transient dynamics of the keyhole in lap welding processes with an interface gap. The model was able to reliably predict the weld profile. In addition, the modeling results provided detailed information regarding the interaction between the molten pool and the solid/liquid boundary that led to the extended weld width. Experimentally, AISI 304 stainless steel was joined in a lap welding configuration using an IPG YLR-1000 fiber laser. The tensile shear and T-peel testing of the lap joints showed that adding an adequate amount of interface gap improves weld strength.

Welding of Austenitic Stainless Steel AISI 304 by Fiber Laser

Paper deals with the welding of AISI 304 thin sheets with the thickness of 1 mm by fiber laser. Statistical software MiniTab was used for planning the experiment. The influence of laser power, welding speed and focal point position on width and depth of weld bead was examined. Output power, welding speed and focus point position were used as variable factors for DOE. Samples were prepared by standard metallography. Weld bead width and depth were evaluated. Statistical results were afterward verified by welding reference samples with material the thickness of 0.25 mm. The difference between real width of weld bead and predicted width obtained from statistical software was 8.26 %. In case of weld depth measurement, the difference was 23 %.

Numerical Analysis of Gas Tungsten Arc Welded AISI 316LN Austenitic Stainless Steel Joints using Response Surface Methodology and Finite Element Anlysis

Numerical Analysis of Gas Tungsten Arc Welded AISI 316LN Austenitic Stainless Steel Joints using Response Surface Methodology and Finite Element Anlysis

Effect of Heat Treatment on the Microstructure and Mechanical Properties of a Welded AISI 410 Martensitic Stainless Steel

2 Abstract: Although martensitic stainless steel materials are not used in large quantities compared to austenitic and ferritic grades, they play a huge and often unseen part in our modern world due to their combination of strength, toughness and moderate corrosion resistance. However, after welding the martensitic stainless steel tend to lose their mechanical/microstructural integrity. In this study, the microstructures and mechanical properties of a welded AISI 410 martensitic stainless steel after different heat treatments were studied, with aims to restore the hardness and improve grain refinement of the materials. The results show that the structures of the steel after austenitizing treatment at 1020°C are of lath martensite mixed with a small amount of retained austenite. Apart from TP2 specimen, where martensite phase was transformed into ferrite structure, the structures of the tempered steel are mixtures of tempered martensite, carbides and reversed austenite dispersed in the martensite matrix. The result indicated that the tempering regimens (500, 600 and 700°C) carried out improved the hardness and grain refinement leading to the existence of finely distributed carbides in the materials. TheTP3 specimen experienced secondary hardening phenomenon, displays the best comprehensive mechanical properties and has the highest hardness value of 370.7 HV close to the parent metal after tempering at 700 °C.

Numerical modeling of non-Fourier heat transfer and fluid flow during plasma arc welding of AISI 304 stainless steel

ABSTRACTThis paper is an attempt to study the evolution of temperature profiles and weld pool geometry during plasma arc welding (PAW) by solving the transient Navier–Stokes and Energy equations. The analysis for an AISI 304 stainless steel rectangular plate was carried out using a flexible written program in Fortran. Due to the low accuracy of the Fourier heat transfer equation for short times and large dimensions, a non-Fourier form of heat transfer equation was used. Gaussian heat source is considered as the heat source model. The fluid flow in the molten pool is of interest because it can change the temperature distribution in and around the molten zone. The governing equations for fluid flow were solved by the finite-volume method in which the SIMPLE method was utilized for pressure–velocity coupling. The effects of heat conduction, fluid flow, and force actions at the weld pool were considered. Thermo-physical properties such as thermal conductivity, specific heat, and dynamic viscosity vary as a function of temperature. There are two mechanisms involved which actively cause heat transfer to the surroundings: radiation and convection heat transfer. The numerical results are compared to the experimental data. The results corroborate that the weld pool thickness in the cross section of PAW and the time taken by molten metal to reach the end of thick metal are in good agreement with the experimental measurements. Finally, the results obtained from the assumed Fourier heat transfer are compared for the same study.

Evolution of Temperature Distribution and Microstructure in Multipass Welded AISI 321 Stainless Steel Plates With Different Thicknesses

Prediction of temperature distribution, microstructure, and residual stresses generated during the welding process is crucial for the design and assessment of welded structures. In the multipass welding process of parts with different thicknesses, temperature distribution, microstructure, and residual stresses vary during each weld pass and from one part to another. This complicates the welding process and its analysis. In this paper, the evolution of temperature distribution and the microstructure generated during the multipass welding of AISI 321 stainless steel plates were studied numerically and experimentally. Experimental work involved designing and manufacturing benchmark specimens, performing the welding, measuring the transient temperature history, and finally observing and evaluating the microstructure. Benchmark specimens were made of corrosion-resistant AISI 321 stainless steel plates with different thicknesses of 6 mm and 10 mm. The welding process consisted of three welding passes of two shielded metal arc welding (SMAW) process and one gas tungsten arc welding (GTAW) process. Finite element (FE) models were developed using the DFLUX subroutine to model the moving heat source and two different approaches for thermal boundary conditions were evaluated using FILM subroutines. The DFLUX and FILM subroutines are presented for educational purposes, as well as a procedure for their verification.

Chemical and Mechanical Characterization of AISI 304 and AISI 1010 Laser Welding

This paper addresses to the dissimilar laser welding of AISI 304 and AISI 1010 steel thin sheets. Cracks-free dissimilar edge fillet welds have been conducted using a Nd:YAG laser. Geometrical, microstructural, chemical, and mechanical proprieties of the welds were investigated using electron microscopy, EDS and tensile test assisted by digital image correlating. The proper results were achieved at an energy density of 88 J/mm2 using a 0.4 mm laser spot diameter. An austenite-ferrite structure characterizes the weld bead and the precipitation of the chromium carbide at the grain limits was observed in the heat affected zone. Good tensile behavior was obtained; dissimilar joint was fractured on the carbon steel side at 482 MPa and 0.35 stain.

Estimation of Average Spot Diameter and Bead Penetration Using Process Model During Electron Beam Welding of AISI 304 Stainless Steel

A mathematical model based on macroscopic heat balance for surface ablation phenomenon and analytical temperature profile below the vapor cavity, has been developed to estimate the average effective spot diameter and predict depth of bead penetration as a function of the processing parameters during electron beam welding of AISI 304 stainless steel. The average beam spot diameter on the work piece surface has been estimated by minimizing the difference between the model prediction and experimental depth of bead penetration. Present experimental data and data from relevant literature have been used to obtain the correlations for beam spot diameter as a function of heat input (i.e. energy input per unit length). Subsequently, a close agreement between the predicted and experimental bead depths is observed.

Effect of Continuous and Pulsed Current on the Metallurgical and Mechanical Properties of Gas Tungsten Arc Welded AISI 4340 Aeronautical and AISI 304 L Austenitic Stainless Steel Dissimilar Joints

In this research work, the weldability of low alloyed AISI 4340 aeronautical steel and AISI 304L austenitic stainless steel joined by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) techniques, using ER309L and ERNiCr-3 filler metals was investigated. The main focus of the study involves the investigation on the effect of continuous and pulsed current mode of GTA welding process on the metallurgical and mechanical properties of these dissimilar weldments. Microstructure studies revealed the formation of different zones across the weldments, vis-a-vis martensite at the HAZ of AISI 4340, vermicular δ - ferrite /ferrite stringers at the HAZ of AISI 304L, pearlite colonies at the parent metal of AISI 4340 and equi-axed cellular and/or columnar dendrites at the weld zone. Tensile results showed that current pulsing accrued better tensile properties. The structure - property relationships of these weldments were established based on the current modes employed by utilizing combined techniques of optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

Correlation of Magnetic Properties and Residual Stress Distribution Monitored by X-Ray and Neutron Diffraction in Welded AISI 1008 Steel Sheets

In this paper, two identical American Iron and Steel Institute 1008 steels sheets were welded together in a butt joint configuration, with the welding line direction parallel to the rolling direction. The sheets were welded using the electron-beam welding technique. Stress distribution was monitored in the surface and the bulk of the welded samples using X-ray Bragg–Brentano and neutron diffraction methods, respectively. Accordingly, surface and bulk magnetic properties, namely magnetic Barkhausen noise and quasi-dc permeability, were monitored in the same area. Both surface and bulk magnetic measurements exhibit good agreement with the surface and bulk stress measurements obtained by the diffraction methods, after a proper calibration procedure. Complementary measurements with scanning electron microscopy and Vicker’s microhardness tester provide similar good agreement between the microstructural characterization and the residual stress distribution.

Developing a Mathematical Model to Predict Tensile Properties of Friction Welded AISI 1035 Grade Steel Rods

In this work, frictions welding of AISI 1035 grade steel rods of 12 mm diameter were investigated with an aim to predict the value of tensile properties. Welds made with various process parameter combinations were subjected to tensile tests. Here, the three factors, five levels, central composite, rotatable design matrix are worn to limit the number of experiments. The mathematical models were developed by response surface method (RSM). The adequacies of the models were checked through ANOVA technique. From developed mathematical models, ultimate tensile strength (UTS) of the joints can be predicted by means of 95 percent confidence level. The integrity of the joints has been investigated using optical microscope.