scholarly journals Residual Stress in Laser Welding of TC4 Titanium Alloy Based on Ultrasonic laser Technology

2018 ◽  
Vol 8 (10) ◽  
pp. 1997 ◽  
Author(s):  
Yu Zhan ◽  
Enda Zhang ◽  
Yiming Ge ◽  
Changsheng Liu
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Laser Welding ◽  
Welding Speed ◽  
Heat Input ◽  
Welding Process ◽  
High Energy ◽  
High Energy Density ◽  
Tc4 Titanium Alloy ◽  
Longitudinal Residual Stress

Laser welding is widely used in titanium alloy welding due to its high energy density, small heat affected zone, and rapid processing ability. However, problems with laser welding, such as deformation and cracking caused by residual stress, need to be resolved. In this paper, the residual stress in laser welding of TC4 titanium alloy was studied using an ultrasonic laser. The residual stress in titanium alloy plates is considered a plane stress state. A pre-stress loading method is proposed and acoustoelastic coefficients are obtained. Based on the known acoustoelastic coefficients, the transverse and longitudinal residual stresses in laser welding are measured using an ultrasonic laser. The results show that longitudinal residual stress is greater than the transverse stress. The distribution regularity of the residual stress is similar to normal welding, but the tensile stress zone is much narrower. Then, the influence of heat input and welding speed on residual stress is discussed. With increasing heat input, the welding zone widens, and the peak value of the residual stress increases. A higher welding speed should be chosen when the welding power is constant. This research has important significance for the measurement and control of residual stress in the laser welding process.

Dissimilar and Similar Laser Beam and GTA Welding of Nuclear Fuel Pin Cladding Tube to End Plug Joint

2017 ◽  
Vol 24 ◽  
pp. 40-47
Author(s):  
Aravind Murugan ◽  
R. Sai Santhosh ◽  
Ravikumar Raju ◽  
A.K. Lakshminarayanan ◽  
Shaju K. Albert
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Laser Beam Welding ◽  
Welding Process ◽  
High Energy ◽  
Optical Microscope ◽  
High Energy Density ◽  
Fuel Pin ◽  
Gtaw Process ◽  
Welding Processes

The end plug to cladding tube of fast reactor fuel pin is normally welded using Gas Tungsten Arc Welding (GTAW) process. The GTAW process has large heat input and wide heat-affected-zone (HAZ) than high energy density process such as laser welding. In the present study Laser Beam Welding (LBW) is being considered as an alternative welding process to join end plug to clad tube. The characteristics of autogenous processes such as GTAW and pulsed Nd-YAG laser welding on fuel cladding tube to end plug joints have been investigated in this study. Dissimilar combinations of modified stainless steel (SS) alloy D9 cladding tube to SS316L end plug, and similar combinations of SS316L cladding tube to SS316L end plug were successfully welded using the above two welding processes. The laser welding was performed at the butting surfaces of the cladding tube and the end plug, and also by shifting the laser beam by 0.2 mm towards the end plug side to compensate the heat balance and for improving the Creq/Nieq ratio in the molten pool. Helium Leak Test (HLT) and Radiography Test (RT) were carried out to validate the quality of the welds. The microstructures of the weld joints were analysed using optical microscope. In the present study, it has been demonstrated that it is possible to obtain welds free from hot cracks by shifting the laser beam by 0.2 mm towards end plug side, while the weld produced using the beam positioned at the interface shows cracks in the weld.

Numerical investigation on the effect of welding speed and heat input on the residual stress of multi-pass TIG welded stainless steel pipe

2020 ◽  
pp. 095440542098133
Author(s):  
Parviz Asadi ◽  
Samaneh Alimohammadi ◽  
Omid Kohantorabi ◽  
Ali Soleymani ◽  
Ali Fazli
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Numerical Investigation ◽  
Welding Speed ◽  
Heat Input ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Stress States ◽  
Three Dimensional Finite Element

A numerical investigation is provided to study the residual stress states in multi-pass TIG welding of stainless steel SUS304 pipe. An uncoupled thermomechanical three-dimensional finite element model is developed using the ABAQUS software for a circular weld design around the pipe. The effects of weld pass numbers, electrode moving speed, and heat input on the internal and external surface tensions of the pipe are investigated. The simulation results show that by increasing the welding speed, the axial tensile stresses decrease on the pipe surfaces. In the case of hoop stress, as the welding speed raises, the tensile and compressive stresses are increased for both two- and three-pass welding. However, the width of the stress zone becomes narrower in higher welding speeds. The hoop stresses, in comparison with the axial stresses, are more strongly influenced by the welding speed and the heat input. Furthermore, using the three-pass welding process results in much lower stresses in comparison with the two-pass one.

The characteristics of high power fibre laser welding

2010 ◽  
Vol 224 (5) ◽  
pp. 1019-1029 ◽  
Author(s):  
A Salminen ◽  
H Piili ◽  
T Purtonen
Keyword(s):  
Laser Welding ◽  
High Power ◽  
Focal Point ◽  
Beam Quality ◽  
Welding Process ◽  
High Energy ◽  
High Energy Density ◽  
Fibre Laser ◽  
Line Energy ◽  
Laser Welding Process

Laser welding has an ever growing role in manufacturing technology. Keyhole laser welding is the most important laser welding process in metal industry when exceeding the 1 mm weld penetration. This process uses efficiently the high energy density of a laser beam to vaporize and melt materials, thus producing a keyhole in the material via which the energy is brought to it. The requirements from customer side and the development of new materials have been giving justification for the development of new laser types suitable for material processing with ever higher power values. In contrast, the development of laser technologies has made it possible to build more powerful lasers with excellent beam properties and good electrical efficiency. New laser sources with good absorption and beam quality make the laser welding even more efficient when throughput and efficiency are considered. They show their ability to produce narrower welds with lower line energy. However, the validation of actual keyhole shape, size, and behaviour against the models is still lacking because of the difficulties in performing the measurements of the actual dimensions. It has been shown that the better the beam quality the higher the welding speed. When welding with high power, good beam quality, and wavelength close to 1000 nm, there are some obstacles to overcome, which are caused by high absorption and power density. Typically, problems, such as thermal lensing, can be avoided with proper parameter and tool selection. Typically, the size of the keyhole is according to the focal point size, and the stability of the keyhole plays a major role when considering the ability of the laser welding process to produce high quality welds.

Residual Stress Analysis and Weld Bead Shape Study in Laser Welding of High Strength Steel

2013 ◽  
Author(s):  
Wei Liu ◽  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Laser Welding ◽  
Welding Speed ◽  
High Strength Steel ◽  
Laser Power ◽  
Measurement Data ◽  
Welding Process ◽  
High Strength ◽  
Weld Bead

The X-ray diffraction (XRD) technique is employed to measure residual stress induced by the laser welding of 6.7 mm thick ASTM A514 high strength steel plates. The distribution of residual stress in the weld bead is investigated. The results indicate that the fusion zone (FZ) has the maximum tensile stress, the transition from tensile to compressive stress tends to appear in the heat affected zone (HAZ), and the initial stress far from the weld center are not influenced by the welding process. Based on the measurement data, the influence of the laser power and the welding speed on residual stress is obtained. The magnitude of residual stress near the weld bead increases with an increase in laser power or a decrease in welding speed. The welds with incomplete penetration have a considerably lower magnitude of residual stress in FZ than ones with full penetration. Post-weld heat treatment is utilized to relieve residual stress in the weld bead. Although residual stress is not completely relieved after the heat treatment, a dramatically reduced magnitude and much more uniform distribution are achieved. In addition, the effects of the laser power, the welding speed, the laser spot diameter, and the gap between two plates on the weld shape are also studied.

Study of Metallurgical and Mechanical Behavior of Laser Butt-Welded Dissimilar Joint of Inconel and Stainless Steel

2019 ◽  
Author(s):  
Sanjib Jaypuria ◽  
Santosh Kumar Gupta ◽  
Sulthan Suresh-Fazeela ◽  
Dilip Kumar Pratihar ◽  
Debalay Chakrabarti ◽  
...  
Keyword(s):  
Laser Welding ◽  
Welding Speed ◽  
Inconel 718 ◽  
Electron Beam Welding ◽  
High Energy ◽  
High Energy Density ◽  
Laser Source ◽  
Laves Phases ◽  
Xrd Phase Analysis ◽  
Welding Processes

Abstract High energy density welding processes like laser and electron beam welding are capable of welding dissimilar plates with much ease due to high power density and low heat input in spite of the varying thermos-physical properties of the used alloys. The present work is aimed to check the feasibility of joint prepared with laser welding of SS 316L and Inconel 718 plates. The experiments are designed to study the effect of welding speed on the mechanical and metallurgical behavior of the joints without any offset to joint line. The formation of laves phases is confirmed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) phase analysis. These laves phase are micro-segregation of Nb, Fe, C and Cr, which is because of high temperature in a small area of fusion zone (FZ) due to intense heat of laser source. Micro-segregation of different elements has led to micro-fissures, which is detrimental for the joints operating at elevated temperature. Cooling rate and peak temperature during welding play the significant role in obtaining a sound quality joint. The present work gives an insight on feasibility of laser welded joint of SS 316L and Inconel 718 with suitable selection of welding speed during laser welding.

The porosity formation mechanism in the laser-welded butt joint of 8 mm thickness Ti-6Al-4V alloy: Effect of welding speed on the metallurgical pore formation

2020 ◽  
Vol 34 (04) ◽  
pp. 2050056
Author(s):  
Deyong Tian ◽  
Zhuanni Gao ◽  
Feiyun Wang ◽  
Tingyan Yan ◽  
Min Yu ◽  
...  
Keyword(s):  
Welding Speed ◽  
Electron Beam Welding ◽  
Welding Process ◽  
High Energy ◽  
Industrial Applications ◽  
Butt Joint ◽  
Hydrogen Gas ◽  
High Energy Density ◽  
Porosity Formation ◽  
Alloy Effect

The high energy density beam welding techniques, such as laser and electron beam welding process, have been widely used in industrial applications. In this study, the butt structures of Ti-6Al-4V alloys with the thickness up to 8 mm are successfully joined by the laser welding process. The macromorphology and microstructures of the welded joints are investigated by a scanning electron microscope (SEM). The penetration increases from 5.91 mm to 9.37 mm with the decrease of welding speed from 1.2 m/min to 0.8 m/min under the condition of equal laser power. The acicular [Formula: see text] is formed in the fusion zone, resulting from high cooling rate during the process. The metallurgical porosity formation is proposed by investigating the distribution of Al and H elements around the pores. It is concluded that the pores in the weld bead are induced by aluminum vapor and hydrogen gas from the molten pool. The diameter of metallurgical pore has a tendency to increase with the decrease of welding speed.

Study the Application of Laser Welding in the Automotive Transmission Parts

2011 ◽  
Vol 189-193 ◽  
pp. 3682-3686
Author(s):  
Guo Liang Chen
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
New Technology ◽  
Welding Process ◽  
Dissimilar Materials ◽  
High Energy ◽  
High Energy Density ◽  
Whole Body ◽  
Workpiece Material ◽  
Safety Standards

Laser beam of high energy density, melting of the workpiece material welded together, can make the heating affected area and change shape minimum, without the use of flux or for dissimilar materials, particularly strong bonding strength. Laser welding is a high energy of the laser beam as heat source a high precision welding. However, the safe application of new technology is the challenge we face. Laser can damage the eyes, skin, respiratory, central nervous and the whole body. It is generally skin safety standards. View of the laser welding process currently used, the possibility of respiratory hazards in the growth of workers with chronic exposure to hazards by the possibility of laser is growing, so the above five aspects of laser hazards should pay attention.

scholarly journals A Study on the Influences of Welding Position on the Keyhole and Molten Pool Behavior in Laser Welding of a Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1082
Author(s):  
Baohua Chang ◽  
Zhang Yuan ◽  
Hao Cheng ◽  
Haigang Li ◽  
Dong Du ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fluid Flow ◽  
Laser Welding ◽  
Weld Pool ◽  
Heat Input ◽  
Welding Process ◽  
Computational Fluid Mechanics ◽  
Weld Quality ◽  
Laser Weld ◽  
Vertical Up

Various welding positions need be used in laser welding of structures with complex configurations. Therefore, it is necessary to gain knowledge of how the welding positions can influence the keyhole and weld pool behavior in order to better control the laser weld quality. In the present study, a computational fluid mechanics (CFD) model was constructed to simulate the laser-welding process of the titanium alloy Ti6Al4V, with which the keyhole stability and the fluid flow characteristics in weld pool were studied for four welding positions, i.e., flat welding, horizontal welding, vertical-up welding, and vertical-down welding. Results showed that the stability of the keyhole was the best in flat welding, the worst in horizontal welding, and moderate in vertical welding positions. Increasing heat input (the ratio of laser power to welding speed) could increase the keyhole stability. When the small heat input was used, the dimensions and flow patterns of weld pools were similar for different welding positions. When the heat input was increased, the weld pool size was increased, and the fluid flow in the weld pool became turbulent. The influences of gravity became significant when a large heat input was used, especially for laser welding with vertical positions. Too high a heat input in vertical-up laser welding would lead to oscillation and separation of molten metal around the keyhole, and in turn result in burn-through holes in the laser weld. Based on the present study, moderate heat input was suggested in positional laser welding to generate a stable keyhole and, meanwhile, to guarantee good weld quality.

scholarly journals Effect of Pre-Heating and Post-Heating on Electron Beam Welding of Reduced Activation Ferrite/Martensite Steel

2021 ◽  
Vol 2 (3) ◽  
pp. 225-238
Author(s):  
Yong Zhang ◽  
Jiefeng Wu ◽  
Zhihong Liu ◽  
Songlin Liu ◽  
Mingzhun Lei ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Electron Beam ◽  
Electron Beam Welding ◽  
Laser Beam Welding ◽  
Welding Process ◽  
High Energy ◽  
High Energy Density ◽  
Post Heat Treatment ◽  
Rafm Steel

Reduced activation ferritic/martensitic (RAFM) steels are considered the main candidate material for the water-cooled ceramic breeder (WCCB) in a fusion reactor. High-energy density welding approaches, such as electron beam welding (EBW) and laser beam welding (LBW), are frequently utilized in the welding of RAFM steels. During the welding process, cracks and other defects are prone to appear. In this paper, EBW was selected for the welding of RAFM steels. Those with and without pre-heat and post-heat treatment by electron beams are studied by finite element simulation and trials. The results show that the experimental results are consistent with the simulation. In particular, in the case of similar deformation, the residual stress after electron beam heat treatment is far less than that without heat treatment. Without heat treatment, the residual stress near the weld is more than 400 MPa, while the residual stress after heat treatment is about 350 MPa. As the reduction of residual stress is essential to prevent the occurrence of cracks and other defects after welding, pre-heat and post-heat treatment by the electron beam is deemed as an effective way to greatly improve the welding quality in RAFM steel welding.

Sign in / Sign up

Export Citation Format

Share Document