Mechanical properties of a dissimilar aluminum alloy joint welded by hybrid laser–MIG welding

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744037 ◽  
Author(s):  
Qiuying Wang ◽  
Hui Chen ◽  
Zongtao Zhu ◽  
Yunlong Cui
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Welded Joint ◽  
Probability Of Failure ◽  
Dissimilar Joint ◽  
Mig Welding ◽  
Welded Structure ◽  
Fatigue Data ◽  
Service Conditions ◽  
The Mean

Two dissimilar Al alloys, 5083-H111 and 6005A-T6, were joined by hybrid laser–MIG welding method. Mechanical properties of the welded joint were investigated and compared. The results show that the tensile strength of the dissimilar joint is 219.8 MPa, 11.7% higher than that of 6005A-T5 joint. After statistical analysis of the fatigue data, the [Formula: see text]–[Formula: see text]–[Formula: see text] curves of the dissimilar joint were obtained. The mean fatigue strength at [Formula: see text] of the dissimilar joint is 112.5 MPa. The fatigue strength at [Formula: see text] of the dissimilar joint for a given 10% probability of failure, at a confidence level of 95%, is 101.4 MPa. The fatigue strength at [Formula: see text] of the dissimilar joint is almost same as that of the 6005A-T6 joint. In welded structure designing, different [Formula: see text]–[Formula: see text]–[Formula: see text] curves should be chosen according to the different service conditions and reliability requirements.

scholarly journals Mechanical Properties of Plug Welds after Micro-Jet Cooling

2016 ◽  
Vol 61 (4) ◽  
pp. 1771-1776 ◽  
Author(s):  
D. Hadryś
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Weld Joint ◽  
Welded Joint ◽  
New Technology ◽  
Mig Welding ◽  
Jet Streams ◽  
Welding Method ◽  
Jet Cooling ◽  
Metal Deposit

Abstract New technology of micro-jet welding could be regarded as a new way to improve mechanical properties of plug welds. The main purpose of that paper was analyzing of mechanical properties of plug welds made by MIG welding method with micro-jet cooling. The main way for it was comparison of plug welds made by MIG welding method with micro-jet cooling and plug welds made by ordinary MIG welding method. It is interesting for steel because higher amount of acicular ferrite (AF) in weld metal deposit (WMD) is obtained in MIG welding method with micro-jet cooling in relation to ordinary MIG welding method. This article presents the influence of the cooling medium and the number of micro-jet streams on mechanical properties of the welded joint. Mechanical properties were described by force which is necessary to destroy weld joint.

scholarly journals Effect of Long-term Service on Microstructure and Mechanical Properties of NiCrMoV Steel Welded Joint

2019 ◽  
Vol 269 ◽  
pp. 03012
Author(s):  
Manjie Fan ◽  
Peng Wang ◽  
Qixing Sun
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Welded Joint ◽  
Welding Process ◽  
Turbine Rotor ◽  
Optical Microscope ◽  
Turbine Plant ◽  
Nicrmov Steel ◽  
Service Conditions

The influences of prolonged service on microstructure evolution and mechanical properties of NiCrMoV steel welded joint in an ex-service welded steam turbine rotor were investigated. The welded rotor had been operated for 22 years since 1991. The specimens for the present study were taken from the location where the temperature was as high as 230°C. The optical microscope (OM) showed that even after long-term service, there were no obvious defects such as creep cavities, cracks found in the microstructure of the whole welded joint after such a long term service. The microstructure was uniform and no obvious grain coarsening was observed. However some black strip-shaped zones were found in base metal and heat affected zone (HAZ). The distribution of hardness across the welded joints showed no anomalies. The results of tensile strength and fracture toughness tests demonstrated that the welded joint still exhibited excellent. Mechanical performance after long-term service, indicating that the welding process of Shanghai Turbine Plant was reliable and stable. With the improvement of forging and welding qualities and improved heat treatment furnaces with more accurately controlled temperature, it is reasonable to assume that the current large low-pressure (LP) welded rotors are definitely safe to operate under similar service conditions for designed life.

Mechanical Properties of Forged Ti-6Al-4V Structure by Electron Beam Welding

2012 ◽  
Vol 455-456 ◽  
pp. 308-313
Author(s):  
Hong Yu Qi ◽  
Jian Xie ◽  
Shao Lin Li ◽  
Xiao Guang Yang
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Fusion Zone ◽  
Electron Beam Welding ◽  
Welded Joint ◽  
Base Material ◽  
Structure Design ◽  
Large Gradient ◽  
Welded Structure ◽  
Aero Engine

The blisk (bladed disk) is a new structural component of the modern aero-engine and plays an important role in improving its performance. Ti-6Al-4V alloy joints welded by electron beam have been widely used for compressor blisk in advanced aero engine. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded structure by electron beam welding (EBW) for failure analysis and structure design of blisk. Microstructure of Ti-6Al-4V welded structure by EBW was investigated by microscopic observation and micro indentation testing. Experiment results show grain coarsening in fusion zone (FZ) and heat affected zone (HAZ) appears large gradient organization structure, which presents significant local heterogeneity. On the centerline perpendicular to the welding direction, Vickers microhardness was measured in increments of 1mm, 0.5mm, 0.25mm and 0.1mm. Due to the presence of martensite, microhardness of the fusion zone is about 20% higher than that of the base material. The size of joints in different regions was acquired, 2.5 to 3.0-mm-wide in FZ and about 0.7-mm-wide in HAZ respectively. Three different types of EBW samples were designed for tensile test, including welded structure, welded joint and base material. Three different stress-strain curves of specimens were acquired, including welded joint. The experiment data indicates that the tensile strength of welded joints is 8% more than that of the base metal.

Codes and Practice of Fatigue Design for Welded Structure

2007 ◽  
Vol 353-358 ◽  
pp. 2828-2831
Author(s):  
Haruo Sakamoto
Keyword(s):  
Statistical Study ◽  
Welded Joint ◽  
Fatigue Testing ◽  
Fracture Probability ◽  
Initial Configuration ◽  
Testing Method ◽  
Japanese Industrial Standard ◽  
Fatigue Design ◽  
Welded Structure ◽  
Fatigue Data

This paper describes codes and practice for designing welded structures such as railroad truck frames. For designing an initial configuration, rather simple criteria are desired, although most codes such as AWS, AISC, etc. are complex. They consist of a variety of welded joint categories, which make a designer feel difficult when deciding the initial configuration. Therefore, such codes are considered to be mainly used for the evaluation of designed and constructed structures, and not to be used for deciding the initial configuration. The JIS (Japanese Industrial Standard) for a railroad truck frame is explained as an example of a simple code, and is compared with some fatigue data. This standard is thought to be useful for a designer. However, the result of this investigation suggests a modification of the JIS for obtaining more reasonable criteria. Desirable criteria should be simple for a designer and sufficiently safe for structures. Additional fatigue data of welded joints, a statistical study for desirable non-fracture probability, and methods of structural stress analysis are to be researched in the future. A practical fatigue testing method is also needed for investigating the strength in a high cycle region such as 108.

scholarly journals Fatigue Strength Evaluation of Welded Structure on Aluminum Alloy Car Body Based on Multi-Axial Stress

2021 ◽  
Author(s):  
Yiming Shangguan ◽  
Wenjing Wang ◽  
Chao Yang ◽  
Anrui He
Keyword(s):  
Shear Stress ◽  
Aluminum Alloy ◽  
Fatigue Strength ◽  
Normal Stress ◽  
Welded Joint ◽  
Axial Stress ◽  
Stress Component ◽  
Local Coordinate System ◽  
Strength Evaluation ◽  
Welded Structure

Abstract With the continuous development of the subway, the demand for its safety and stability is getting higher and higher. It is of great significance to accurately evaluate the fatigue life of the carbody to ensure the subway's safe operation. In this paper, the finite element model of a subway head carbody was established, and the fatigue strength of the welded structure on the carbody was evaluated based on Multi-axial stress. The local coordinate system was defined according to the geometrical characteristics of the welds. Local stresses perpendicular and parallel to the weld seam were obtained to calculate the stress ratio, stress range, and allowable stress value corresponding to the stress component. According to the joint fatigue resistance, the components of the degree of utilization and comprehensive degree of utilization are calculated to evaluate the structural fatigue strength under the survival rate of 97.5% and load cycles of 10 7 . The evaluation of the fatigue strength of the pivotal weld joints shows that the fatigue strength of the aluminum alloy carbody meets the design requirements, the weld of the carbody has a strong ability to resist fatigue damage. The fatigue strength of the weld is mainly affected by the normal stress component, while the shear stress has little effect on the fatigue strength of the structure. In addition, compared with the filleted weld joint and the butt-welded joint, the normal stress parallels to and perpendicular to the weld direction and shear stress have the greatest effect on the lap-welded joint. Meanwhile, the comprehensive degree of utilization of the lap-welded joint is the largest at 0.49. The introduction of multi-axial stress for the fatigue strength evaluation is beneficial when considering the material utilization degree in multiple structural directions. This research results provide a reference for fatigue strength evaluation of subway carbody's welded structure.

scholarly journals Effect of ultrasonic impact time on Microstructure and properties of 7A52 aluminum alloy tandem MIG welded joint

2021 ◽  
Author(s):  
Furong Chen ◽  
Yihang Yang ◽  
Nan Li
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Welded Joint ◽  
Treatment Time ◽  
High Strength ◽  
Proper Treatment ◽  
Welding Condition ◽  
7A52 Aluminum Alloy

Abstract 7A52 (Al-Zn-Mg-Cu) alloy is a high-strength aluminum alloy, its welded joints are often accompanied by defects such as poor wear resistance and low fatigue strength. Herein, we try to optimize the welded joint of 7A52 aluminum alloy by using ultrasonic impact treatment (UIT). Generally, the mechanical properties such as microhardness and fatigue strength of the welded joint after UIT will be improved. 7A52 aluminum alloy tandem metal inert gas (MIG) welded joints with UIT time per unit area of 2.5 min, 5 min, 10 min, 15 min, 30 min, and 75 min were studied. Through the surface topography, microstructure observation, and mechanical properties test, the time parameters of excessive treatment, lack of treatment, and proper treatment were selected, and the effects of UIT, excessive treatment, lack of treatment, and proper treatment on fatigue strength were analyzed. Test results show that, the mechanical properties of welded joints after UIT are improved. The proper treatment time is 15min and its fatigue strength is 37.86MPa, respectively under the stress ratio of 0.1. Compared to the original welding condition with a fatigue strength of 28.61MPa, the fatigue strength of the welded joints of 7A52 aluminum alloy increased by 32.33%. The largest percentage of grain size reduction occurs when the UIT is 15 min. Moreover, excessive treatment and lack of treatment will not further refine the grains and optimize the mechanical properties.

Fatigue Design of the Railroad Car Body Member Using a Simulated Single Spot Welded Joint

2007 ◽  
Vol 353-358 ◽  
pp. 2809-2811
Author(s):  
Dong Ho Bae ◽  
Sol Bin Lee ◽  
Sun Kyu Park
Keyword(s):  
Fatigue Strength ◽  
Welded Joint ◽  
Design Method ◽  
Lap Joints ◽  
Design Criterion ◽  
Single Spot ◽  
Car Body ◽  
Fatigue Design ◽  
Fatigue Data ◽  
Spot Welded

In order to develop a fatigue design method for the actual railroad car body structures using the fatigue data on simulated single spot welded lap joints, firstly, evaluated fatigue strength on the spot welded t-type member which is a component of the actual railroad car body structure. And next, possibility of fatigue design for spot welded T-type member using the fatigue data of single spot welded lap joints was investigated. From the results, it was found that, even though there is some difference in fatigue strength between single spot welded joint and the actual members under the same fatigue life, the fatigue design criterion could be predicted by correction between them.

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