Effect of ultrasonic impact treatment on surface microstructure and fatigue properties of 6082 aluminum alloy butt joint

2018 ◽  
Vol 32 (21) ◽  
pp. 1850239 ◽  
Author(s):  
Bolin He ◽  
Yaming Feng ◽  
Li Li ◽  
Zhaoxia Chen
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Crack Initiation ◽  
Welded Joint ◽  
Butt Joint ◽  
Fatigue Properties ◽  
Ultrasonic Impact Treatment ◽  
Transmission Electron ◽  
Weld Toe ◽  
6082 Aluminum Alloy

Effect of ultrasonic impact treatment (UIT) on microstructure and fatigue properties of the aluminum alloy 6082 was studied at room temperature. The change of microstructure on the surface and the grain size after impact treatment was observed by metallographic microscope and transmission electron microscopy, respectively. The residual stress was measured by residual stress tester. The experimental results show that the UIT can lead to obvious plastic deformation layer in the treated surface, and nanocrystals were formed. Compressive residual stress of 50.4 MPa was maximum at the surface after the UIT. With an impact current of 1.0 A and impact time of 2 min, compared with untreated specimens, the fatigue strength of the 6082 aluminum alloy joint increases by about 11.18%. The fracture position for the treated specimen has been changed, the crack initiation is seen in the weld toe surface for the as-welded joint, and the crack initiation in the sub-surface for the treated specimen is comparable to the as-welded joint fatigue.

Research about the Effect of Ultrasonic Impact on the Mechanical Property of Welded Butt Joint of P355NL1 Steel

2014 ◽  
Vol 644-650 ◽  
pp. 4752-4755
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Zhi Jun Zhang ◽  
Jian Ping Shi
Keyword(s):  
Mechanical Property ◽  
Residual Stress ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Butt Joint ◽  
Impact Machine ◽  
Ultrasonic Impact Treatment ◽  
Weld Toe ◽  
The Impact ◽  
Scanning Electron

Surface treatment was carried out on the butt joint weldment of P355NL1 steel by using the HJ-II-type ultrasonic impact machine. The ultrasonic impact current is 1.5A, the impact amplitude is 20 microns and ultrasonic impacting time is 5min. Tensile test was carried out for both treated specimen and un-treated specimen. The fracture observed with the scanning electron microscope of 6360LA type. The experimental results show that although the compressive residual stress can be obtained in the surface of weld toe area, and the grain size in the welded joint can be refined, but the mechanical property of the butt joint of P355NL1 steel can not be improved through the ultrasonic impact treatment. The main reason is that the ultrasonic impact layer is only 120um, it is to thin to compared to the thickness of the specimen.

Research about the Effect of Ultrasonic Impact on the Fatigue Life of Butt Weld Joint of 16MnR Steel

2011 ◽  
Vol 189-193 ◽  
pp. 3296-3299
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Huang Huang Yu ◽  
Jian Ping Shi
Keyword(s):  
Fatigue Life ◽  
Welded Joint ◽  
Butt Joint ◽  
Impact Machine ◽  
Ultrasonic Impact Treatment ◽  
Butt Weld ◽  
Impact Time ◽  
Weld Toe ◽  
The Impact ◽  
Fatigue Experiment

Surface treatment was carried out on the butt joint weldment of 16MnR steel by using the HJ-II-type ultrasonic impact machine. The ultrasonic impact current is 1.2A, the impact amplitude is 30 microns and ultrasonic impacting time is 30min and 60 min,respectively. Fatigue experiment was carried out for both treated specimen and un-treated specimen. The fatigue fracture observed with the scanning electron microscope of 6360LA type. The experimental results show that the fatigue life of the butt joint weldment of 16MnR steel can be significantly improved through the ultrasonic impact treatment. The main reason is that the ultrasonic impact can reduces the stress concentration in the weld toe, decrease the tensile stress, and even change to compressive stress in the weldment, the grain size in the welded joint can be refined. The longer the impact time, the greater increasing range of fatigue life will be. Compared to the sample without treatment, its fatigue life was increased 375.22%, 521.24%, respectively, when the impact time was 30, 60min, respectively.

scholarly journals Study on Microstructure and Fatigue Damage Mechanism of 6082 Aluminum Alloy T-Type Metal Inert Gas (MIG) Welded Joint

2018 ◽  
Vol 8 (10) ◽  
pp. 1741 ◽  
Author(s):  
Chenfeng Duan ◽  
Shanglei Yang ◽  
Jiaxing Gu ◽  
Qi Xiong ◽  
Yuan Wang
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Fracture ◽  
Molten Pool ◽  
Welded Joint ◽  
Fatigue Cracks ◽  
Weld Line ◽  
Grain Morphology ◽  
Inert Gas ◽  
Fatigue Properties ◽  
6082 Aluminum Alloy

In this experiment, the T-joint of a 6082 aluminum alloy was welded by metal inert gas (MIG) welding and a fatigue test was carried out at room temperature. The mechanisms of generating pores and of fatigue fracture in welded joints are revealed in the case of incomplete penetration. There are two main types of pores: pores that are not welded and pores that are near the upper weld line of the weld. During welding, bubbles in the molten pool are adsorbed on the surface oxide film that is not penetrated, and cannot be floated to form pores; since it is a T-shaped welded joint, the molten pool is overhanged during welding, thereby forming pores near the fusion line. The fatigue strength of the welded joint based on the S–N curve at 107 cycles is estimated to be 37.6 MPa, which can reliably be predicted in engineering applications. Fatigue tests show that fatigue cracks are all generated in the pores of the incomplete penetration, and it and the pores form a long precrack, which leads to large stress concentration, and the fracture occurs under a small applied load. Grain morphology around the pores also has a large effect on the fatigue properties of the T-weld joint. In the weld’s fatigue fracture, it was found that the crack stable-extension zone exhibited ductile-fracture characteristics, and the instantaneous fault zone is composed of a large number of tear-type dimples showing ductile fractures.

Effect of Different Filler Towards Welding of AA6061 Al Alloy by X-Ray CT Scan

2010 ◽  
Vol 146-147 ◽  
pp. 1402-1405 ◽  
Author(s):  
Che Lah Nur Azida ◽  
Azman Jalar ◽  
Norinsan Kamil Othman ◽  
Nasrizal Mohd Rashdi ◽  
Md Zaukah Ibel
Keyword(s):  
Aluminum Alloy ◽  
Ct Scan ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
Butt Joint ◽  
Al Alloy ◽  
X Ray ◽  
Metal Arc Welding ◽  
Joint Quality ◽  
Filler Metals

AA6061 Aluminum alloy welded joint using two different filler metals were studied by using X-ray CT-Scan. The filler metals ER 4043 and ER 5356 were used in this present work in order to investigate the effect of using different filler metals on the welded joint quality of AA 6061 aluminum alloy in welded zone microstructure. Gas metal arc welding (GMAW) technique and V grove butt joint with four layers and five passes welded joint were performed. From this investigation, it is found that AA6061 with ER 4043 showed less distribution of porosity compared to AA6061 with ER 5356 welded joint confirmed by X-ray Ct-Scan. The decreasing of porosities and presence of very fine grains in weld region area with ER 5356 compared to ER 4043 will be discussed in term of microstructure analysis.

Effect of the Rheocasting Process and of the SLS Layer on the Fatigue Behavior of 357 Aluminum Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 227-234 ◽  
Author(s):  
Alain Abou Antoun ◽  
Myriam Brochu ◽  
Heinrich Möller
Keyword(s):  
Aluminum Alloy ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Initiation Mechanism ◽  
Liquid Segregation ◽  
Surface Liquid ◽  
Effect Of Surface

Two objectives were targeted: 1) compare the high cycle fatigue behavior of rheocast aluminum alloy 357 prepared by the swirl enthalpy equilibration device (SEED) and by the Council for Scientific and Industrial Research (CSIR) process, and 2) study the effect of surface liquid segregation (SLS) on the fatigue behavior of the CSIR material. Rectangular hourglass specimens machined from rheocast plates were tested at four stress amplitudes in axial fatigue with a stress ratio of R = -1 and a frequency of 20 Hz. Results obtained for SLS free specimens show that the SEED and the CSIR processes produce rheocast materials with comparable high cycle fatigue properties, 115 MPa at 107 cycles. In order to study the influence of surface liquid segregation, slightly polished specimens with a remaining SLS of nearly 750 microns thick were also tested. According to the results, the SLS reduces the average fatigue strength by approximately 5% (110 MPa vs. 115 MPa at 107 cycles). For SLS free specimens, the fatigue crack initiated at shrinkage cavities, oxide films or in the alpha globules. On the other hand, for specimens with SLS, no crack initiation in the alpha globules was observed. The main crack initiation mechanism was identified to be a deformation incompatibility between regions characterized by higher silicon content compared to nominal eutectic regions. The originality of the work is provided by the rigorous comparative analysis of the fatigue performance of components produced in two different rheocasting facilities, but tested in a single laboratory. It is also the first fundamental research published on the mechanical effect of surface liquid segregation. It confirms that SLS should be removed in critical areas in order to optimize the fatigue resistance of rheocast components.

Research about the Effect of Ultrasonic Impact on the Mechanical Property of Welded Cruciform Joint of P355NL1 Steel

2014 ◽  
Vol 644-650 ◽  
pp. 4748-4751
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Si Yong Lei ◽  
Jian Ping Shi
Keyword(s):  
Mechanical Property ◽  
Residual Stress ◽  
Grain Size ◽  
Compressive Residual Stress ◽  
Impact Machine ◽  
Ultrasonic Impact Treatment ◽  
Weld Toe ◽  
The Impact ◽  
Cruciform Joint ◽  
Scanning Electron

Surface treatment was carried out on the welded cruciform joint of P355NL1 steel by using the HJ-II-type ultrasonic impact machine. The ultrasonic impact current is 1.5A, the impact amplitude is 20 microns and ultrasonic impacting time is 5min. Tensile test was carried out for both treated specimen and un-treated specimen. The fracture observed with the scanning electron microscope of 6360LA type. The experimental results show that although the compressive residual stress can be obtained in the surface of weld toe area, and the grain size in the surface of welded cruciform joint can be refined, but the mechanical property of the welded cruciform joint of P355NL1 steel can not be improved through the ultrasonic impact treatment. The main reason is that the ultrasonic impact layer is only 70um, it is to thin to compared to the thickness of the specimen.

Review of Status about the Effect of Ultrasonic Impact on Fatigue Properties of Welded Joints of Magnesium Alloy

2013 ◽  
Vol 668 ◽  
pp. 835-839 ◽  
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Bin Wang ◽  
Shang Yu Zhou
Keyword(s):  
Residual Stress ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Welded Joints ◽  
Welded Joint ◽  
Development Trend ◽  
Fatigue Properties ◽  
Concentration Coefficient ◽  
The Development Trend ◽  
Stress Concentration Coefficient

The study on magnesium alloy has attracted attention at home and abroad. Status and development trend about the fatigue properties of welded joints of magnesium alloy were reviewed. The main problems and deficiencies were pointed out, and the recent development's focus was outlined. The development trend of improving the fatigue propeties and fatigue life was analyzed. The ultrasonic impact method can not only decrease the stress concentration coefficient and tensile residual stress of welded joint, but also refine the grain size of welded joints, even to compressive stress and nanograins. The method has put forward a new way for increasing fatigue properties and life of welded joint of magnesium alloy.

Study on the Fatigue Properties of the TIG Weld Joint with the Stainless Steel Conduit in Aircraft

2015 ◽  
Vol 664 ◽  
pp. 104-110
Author(s):  
Ying Liu ◽  
Dong Jie Li ◽  
Xiao Hong Li
Keyword(s):  
Stainless Steel ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Weld Joint ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Research Focus ◽  
Weld Toe ◽  
Crack Initiation Life

The research focus on the material of the stainless steel thin conduit in aircraft, named 1Cr18Ni9Ti , and the TIG weld joint of which was investigated to analysis the fatigue properties. The fracture mechanics was used to analysis the crack initiation life and crack propagation life, and the fatigue surface was characterized with scanning electron microscope (SEM). The experimental and analytical results show that, the origin position of fatigue crack is the surface of the conduit. The stress concentration at the weld toe, the crystal structure is not uniform and Stress concentration in the heat affected zone (HAZ) and fusion line, so the fatigue cracks are easily generated in these locations. Delta K increases to a certain value, the HAZ has become one of the most dangerous position. The crack initiation life of HAZ in the total fatigue life is far higher than the proportion of crack propagation life.

Influence of Deep Rolling Process Parameters on Surface Residual Stress of AA7075-T651 Aluminum Alloy Friction Stir Welded Joint

2018 ◽  
Vol 939 ◽  
pp. 23-30 ◽  
Author(s):  
Adirek Baisukhan ◽  
Wasawat Nakkiew
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Rolling Process ◽  
Rolling Speed ◽  
Deep Rolling ◽  
Friction Stir ◽  
Rolling Pressure

Friction stir welding is most commonly used for joining aluminum alloy parts. After welding, residual stresses occurred in the welded joint caused by non-uniform cooling rate. Friction stir welding usually generates tensile residual stress inside the workpiece which affects the strength in addition to the fatigue life of materials. Compressive residual stress usually is beneficial and it can be introduced by mechanical surface treatment methods such as deep rolling, shot peening, laser shock peening, etc. In this research, deep rolling was used for inducing compressive residual stress on surface of friction stir welded joint. The residual stresses values were obtained from X-ray diffraction machine. Influence of three deep rolling process parameters: rolling pressure, rolling speed and rolling offset on surface residual stresses at the welded joint were investigated. Each factor had 2 levels (23 full factorial design). The statistical analysis result showed that the rolling pressure, rolling speed, rolling offset, interaction between rolling pressure and rolling speed, interaction between rolling speed and rolling offset were statistically significant factors, with the most compressive residual stress value approximately -391.6 MPa. The appropriated deep rolling process parameters on surface residual stress of AA7075-T651 aluminum alloy friction stir welded joint were 1) rolling pressure about 150 bar 2) rolling speed about 1,400 mm/min 3) rolling offset about 0.1 mm.

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