Enhanced Mechanical Properties of AA5083 GTA Weldments with Current Pulsing and Addition of Scandium

2013 ◽  
Vol 765 ◽  
pp. 716-720 ◽  
Author(s):  
N. Kishore Babu ◽  
Patil Yogesh Bhikanrao ◽  
K. Sivaprasad
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fusion Zone ◽  
Weld Zone ◽  
Solidification Structure ◽  
Grain Structure ◽  
Welding Parameters ◽  
Pulsed Current ◽  
Current Technique ◽  
Aa5083 Alloy

AA5083 alloy is welded with gas tungsten arc welding using optimized welding parameters. Al-Si-Sc master alloy filler with varying contents of scandium is used for welding. Welding was carried out with and without AC-pulsed current techniques. A narrow heat affected zone with more refined grain structure is observed in the case of the pulsed current technique. Furthermore, it is observed that the columnar solidification structure in the fusion zone was suppressed and fine equiaxed grains were formed in the weld zone with increasing scandium content, which is attributed to the grain refinement effect of scandium with the generation of increased nucleating sites during weld solidification. This effect is reflected in mechanical properties also. An increased hardness of about 10 % results with pulsed current technique compared to about 20 % with an addition of 0.75 % scandium. However, in the case of tensile properties pulsing resulted in about 8 % increase in tensile strength and addition of 0.75 % scandium resulted in about 40 % increase in tensile strength. Both the pulsed current technique and the addition of scandium were observed to be better in increasing not only strength but also elongation due to the refined grain structure in the weld fusion zone.

scholarly journals Optimizing the Integrity of Linear Friction Welded Ti2AlNb Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 802
Author(s):  
Xi Chen ◽  
Zhao Zhang ◽  
Faqin Xie ◽  
Xiangqing Wu ◽  
Tiejun Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Process Parameters ◽  
Precipitation Hardening ◽  
Weld Zone ◽  
Aging Treatment ◽  
Weld Interface ◽  
Welding Parameters ◽  
Linear Friction ◽  
O Phase

The knowledge of process parameters–weld integrity-aging treatments–tensile property relationship is of great concern for linear friction welded (LFWed) Ti2AlNb-based alloy and requires a systematic characterization. Thus, the Ti2AlNb-based alloy was LFWed under various process parameters and then subjected to different aging treatments. Twelve welding conditions were used to evaluate the weld integrity, showing that impurities and cracks at weld interface can be eliminated under strong welding parameters and the feed rate has the greatest influence on the weld integrity among all process parameters. Relationships among aging temperatures, microstructure evolution, and mechanical properties were investigated. After aging treatment, acicular O phase has precipitated in B2 grains both in the weld zone and thermo-mechanical affected zone (TMAZ). The size of precipitated O phase increases along with the increase of temperature, and the α2 +·O mixtures have finally decomposed into the aggregated acicular O phase. The microhardness and tensile strength of the joints have been enhanced due to the precipitation hardening of O phase and refined grain strengthening after aging treatments.

Pulsed TIG Welding of Al–SiC Composite: Welding Parameter Optimization

2019 ◽  
Author(s):  
P. Sivachidambaram ◽  
Raghuraman Srinivasan ◽  
Venkatraman Ramamoorthy
Keyword(s):  
Tensile Strength ◽  
Cooling Rate ◽  
Weld Zone ◽  
Pulse Frequency ◽  
Regression Equation ◽  
Welding Parameters ◽  
Pulsed Current ◽  
Base Current ◽  
Bending Load ◽  
Pulse On Time

Pulse on time, pulse frequency, peak current, and base current are the important parameters to be optimized in pulsed current tungsten inert gas (PCTIG) welding of Al–SiC metal matrix composite. Experiments were designed and conducted using the L9 orthogonal array technique. The regression equation was developed using Design Expert® statistical software package to predict the weld center’s micro hardness, yield strength, ultimate strength, elongation (%), bending load, weld depth, weld width, cooling rate, and peak temperature near the weld zone of Al-8% SiC composite, welded using PCTIG welding. Correlation coefficient shows 0.9 for all the mechanical properties. This showed that the regression equation and the mathematical model developed were adequate. Analysis of contour plot, interaction effect, signal-to-noise ratio, and mean response were developed, the influence of each pulsed current parameter was evaluated at each level, and the percentage of influence was calculated by using pulsed current parameters. Ultimate tensile strength and bending load values depend on the microstructure. When the cooling rate is higher, fine microstructures are observed due to grain refinement; higher tensile strength and bending load are also observed. Due to the decreased cooling rate, coarse microstructures are observed, which result in poor tensile strength and bending load. PCTIG welding parameters are responsible for the change in the cooling rate of the weld zone. The optimization of the PCTIG welding parameters shows that the peak current and base current should be 160 and 60 A, respectively. Pulse on time is recommended to be 50%–55% and pulse frequency to be 5 Hz.

Prediction of Weld Strength of PC-TIG Welded Al-8% SiC Metal Matrix Composite – An Empirical Model (EM) Approach

2015 ◽  
Vol 813-814 ◽  
pp. 467-473
Author(s):  
Sivachidambaram Pichumani ◽  
Krishnamoorthy Balachandar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Empirical Model ◽  
Metal Matrix ◽  
Tig Welding ◽  
Weld Strength ◽  
Welding Parameters ◽  
Pulsed Current ◽  
Bend Strength

This work is focused on the development of empirical model to predict the mechanical properties of welded Al-SiC metal matrix composites. Autogenous pulsed current-Tungsten inert gas (PC-TIG) welding was performed on 5mm thick Al-8%SiC composite plates. Regression equations were developed to predict the tensile strength, yield strength, percentage of elongation and bend strength of pulsed current TIG weld Al-SiC composite by varying weld parameters such as peak current, base current, pulse on time and pulse frequency. The effect of each pulsed current TIG welding parameters and interaction between two more parameters on the ultimate tensile strength, yield strength, percentage of elongation and bend strength were studied for clear understanding of PCTIG welding parameters. Improved mechanical properties viz. 136 MPa tensile strength, 117 MPa yield strength with 15% elongation were achieved using optimal PCTIG welding parameters. The predicted values were experimentally verified for consistency and validation. This study also resulted in understanding the significant factors which were responsible for improved weld strength of the chosen candidate material.

scholarly journals Effect of molybdenum addition on microstructure and mechanical properties of plain carbon steel weld

10.30544/245 ◽  
2016 ◽  
Vol 22 (4) ◽  
pp. 269-284
Author(s):  
Jyoti Menghani ◽  
Kunal Dwivedi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Process Parameters ◽  
Welding Speed ◽  
Welding Process ◽  
Grain Structure ◽  
Welding Parameters ◽  
Bead Width ◽  
Arc Voltage ◽  
Molybdenum Carbides

The present investigation has two main objectives; first is optimization of welding process parameters of submerged arc welding (SAW) using Taguchi philosophy and second is to improve the mechanical properties such as strength and microhardness of weld joint by alloying with varying amounts of molybdenum. For optimization of welding process, parameters Taguchi philosophy have been applied on a mild steel plate (AISI C- 1020) of 10 mm thickness with 60o groove angle with arc voltage and welding speed as variables and bead width as output variables. A mathematical relationship between bead width, arc voltage and welding speed has also been found using multiple regression analysis for the present base metal plate geometry. After optimizing welding parameters, molybdenum has been added individually to the welding area in varying percentages. The properties of alloyed and unalloyed weld metal bead are compared. The mechanical characterization of weld has been done in terms of microhardness, tensile strength, whereas microstructural characterization has been performed using optical microscopy, XRD and EDS. The presence of molybdenum resulted in bainite structure in weld bead having a refined grain structure, enhancement in tensile strength and microhardness. The XRD results showed the formation of molybdenum carbides justifying the increase in microhardness value.

Effects of bottom plate in friction stir welding of AA6061-T6

2020 ◽  
Vol 118 (1) ◽  
pp. 108
Author(s):  
M.A. Vinayagamoorthi ◽  
M. Prince ◽  
S. Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Axial Load ◽  
Weld Zone ◽  
Welding Process ◽  
Bottom Plate ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Friction Stir ◽  
Weld Joints ◽  
Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

scholarly journals Influence of the Heat Input on the Dendritic Solidification Structure and the Mechanical Properties of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal

2021 ◽  
Author(s):  
Hannah Schönmaier ◽  
Ronny Krein ◽  
Martin Schmitz-Niederau ◽  
Ronald Schnitzer
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Heat Input ◽  
Stress Rupture ◽  
Pressure Vessels ◽  
Rupture Time ◽  
Solidification Structure ◽  
Welding Parameters ◽  
Austenite Grain Size ◽  
Submerged Arc

AbstractThe alloy 2.25Cr-1Mo-0.25V is commonly used for heavy wall pressure vessels in the petrochemical industry, such as hydrogen reactors. As these reactors are operated at elevated temperatures and high pressures, the 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep properties. The mechanical properties are known to be influenced by several welding parameters. This study deals with the influence of the heat input during submerged-arc welding (SAW) on the solidification structure and mechanical properties of 2.25Cr-1Mo-0.25V multilayer metal. The heat input was found to increase the primary and secondary dendrite spacing as well as the bainitic and prior austenite grain size of the weld metal. Furthermore, it was determined that a higher heat input during SAW causes an increase in the stress rupture time and a decrease in Charpy impact energy. This is assumed to be linked to a lower number of weld layers, and therefore, a decreased amount of fine grained reheated zone if the multilayer weld metal is fabricated with higher heat input. In contrast to the stress rupture time and the toughness, the weld metal’s strength, ductility and macro-hardness remain nearly unaffected by changes of the heat input.

The effect of vibratory conditioning on tensile strength and microstructure of 1018 mild steel

2020 ◽  
Vol 17 (6) ◽  
pp. 837-844 ◽  
Author(s):  
Venkata Suresh Bade ◽  
Srinivasa Rao P. ◽  
Govinda Rao P.
Keyword(s):  
Tensile Strength ◽  
Mild Steel ◽  
Fusion Zone ◽  
Dc Motor ◽  
Grain Structure ◽  
Internal Stresses ◽  
Skilled Workers ◽  
Mechanical Vibrations ◽  
Content Type ◽  
Weld Defects

Purpose The purpose of this paper is to investigate the prominence of mechanical excitations at the time of welding. In the past years, the process of welding technology has expanded its influence in manufacturing. The crucial drawback of conventional welding is prompted by internal stresses and distortions, which is the focal reason for weld defects. These weld defects can be diminished by the process called post-weld heat treatment (PWHT), which consumes more working hours and needs skilled workers. To replace these PWHT processes, mechanical vibrations are introduced during the process of welding to diminish these weld defects. Design/methodology/approach In the current research, the mechanical vibrations are transferred to weld-pool through vibro-motor and DC motor connected to the electrode. As per standards, the tensile test specimens were prepared for welding with different voltages of vibro-motor and DC motor respectively. The weld joints were tested for tensile strength and analyzed the microstructure at the fusion zone. Findings Melt-ability at fusion zone of 1018 mild steel was investigated by the single-stroke intense heat process of fusion welding. It is observed that the mechanical vibrations technique has a profound influence on the enhancement of the fusion zone characteristics and grain structure. The peak value of the tensile strength is observed at 100 s of vibration, 190 V of vibro-motor voltage and 18 V of electrode voltage. The tensile strength of the welded joints with vibrations is increased up to 22.64% when it is compared with conventional welding. The enhancement of the tensile strength of the weld bead was obtained because of the formation of fine grain structure. So, mechanical vibrations are identified as the most convenient method for improving the mild steel alloys weld quality. Originality/value A novel approach called mechanical vibrations during the process of welding is implemented for fusion zone refinement.

Optimizing Pulsed Current Micro Plasma Arc Welding Parameters to Maximize Ultimate Tensile Strength of AISI 304L Sheets Using Response Surface Method

2014 ◽  
Vol 660 ◽  
pp. 322-326
Author(s):  
Kondapalli Siva Prasad ◽  
Chalamalasetti Srinivasa Rao ◽  
Damera Nageswara Rao
Keyword(s):  
Mathematical Model ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Response Surface ◽  
Response Surface Method ◽  
Welding Parameters ◽  
Pulsed Current ◽  
Plasma Arc ◽  
Aisi 304L ◽  
Surface Method

AISI 304L is an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength and ductility. These attributes make it a favorite for many mechanical components. The paper focuses on developing mathematical model to predict ultimate tensile strength of pulsed current micro plasma arc welded AISI 304L joints. Four factors, five level, central composite rotatable design matrix is used to optimize the number of experiments. The mathematical model has been developed by response surface method. The adequacy of the model is checked by ANOVA technique. By using the developed mathematical model, ultimate tensile strength of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters ultimate tensile strength of AISI 304L steel. The developed mathematical model has been optimized using Response Surface Method to maximize the ultimate tensile strength.

Effects of Welding Wire Composition on Microstructure and Mechanical Properties of Welded Joint in Al-Mg-Si Alloy

2022 ◽  
Vol 905 ◽  
pp. 44-50
Author(s):  
Li Wang ◽  
Ya Ya Zheng ◽  
Shi Hu Hu
Keyword(s):  
Mechanical Properties ◽  
Fusion Zone ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Weld Zone ◽  
Xrd Analysis ◽  
Metallographic Analysis ◽  
Strengthening Effect ◽  
Welding Wire ◽  
Microstructure And Mechanical Properties

The effects of welding wire composition on microstructure and mechanical properties of welded joint in Al-Mg-Si alloy were studied by electrochemical test, X-ray diffraction (XRD) analysis and metallographic analysis. The results show that the weld zone is composed of coarse columnar dendrites and fine equated grains. Recrystallized grains are observed in the fusion zone, and the microstructure in the heat affected zone is coarsened by welding heat. The hardness curve of welded joint is like W-shaped, the highest hardness point appears near the fusion zone, and the lowest hardness point is in the heat affected zone. The main second phases of welded joints are: matrix α-Al, Mg2Si, AlMnSi, elemental Si and SiO2. The addition of rare earth in welding wire can refine the grain in weld zone obviously, produce fine grain strengthening effect, and improve the electrochemical performance of weld.

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