Effect of the temperature gradient on hot cracking susceptibility for electron beam welding Alloy 247 LC

Abstract Conventionally cast Alloy 247 LC is characterized by good creep rupture strength and corrosion resistance at high temperatures and is therefore frequently used for cast components in the aero-engine and power generation industries. From a welding technology point of view, the precipitation- hardening nickel-based alloy has an increased susceptibility to hot cracking. Due to its high segregation tendency and its γ’ precipitation formation, the material is even classified as non-weldable. However, electron beam welding in a vacuum as the method of choice for joining and repairing nickel-based components in industrial practice, provides a variable beam welding process with high energy density. This allows varied temperature gradients to be implemented. In this paper, results of welding parameter optimization with regard to hot crack reduction are presented. For this purpose, a comprehensive crack analysis was carried out using scanning electron microscopy, metallography and X-ray microtomography and was then compared with the temperature gradient along the fusion line. Two hot cracking phenomena were identified and differentiated. Thereby, a clear dependence between temperature gradient and crack reduction becomes obvious.

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

Journal of Nuclear Engineering ◽

10.3390/jne2030021 ◽

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.

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Development of Cathode Filament Power Supply for EBW Based on ARM

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.960-961.1300 ◽

2014 ◽

Vol 960-961 ◽

pp. 1300-1303

Author(s):

Ze Ting Wang ◽

Peng Liu ◽

Sheng Wen Fan

Keyword(s):

Electron Beam ◽

Power Supply ◽

Electron Beam Welding ◽

High Volume ◽

High Energy ◽

High Energy Density ◽

Shipping Industry ◽

Soft Start ◽

Power Frequency ◽

Low Efficiency

The electron beam welding has high energy density, and has been widely applied in air space, the car and shipping industry. Traditional electron beam welding machine power supply system adopts the technology of the power frequency or medium frequency, with high volume, low efficiency and poor stability of electron beam. I put forward a digital filament power control scheme based on STM32, and introduce the hardware and software implementation method in detail. Experiments show that it can realize soft-start and soft-down process, and also be quickly identified and promptly forbid the output when filament fracture, which realize the intellectualization of filament power supply.

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Heat Transfer Modeling for Vaporizing in Vacuum Electron Beam Welding on Magnesium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.681.314 ◽

2013 ◽

Vol 681 ◽

pp. 314-318

Author(s):

Yi Luo

Keyword(s):

Heat Transfer ◽

Electron Beam ◽

Magnesium Alloy ◽

Electron Beam Welding ◽

High Energy ◽

High Energy Density ◽

Deep Penetration ◽

Transfer Model ◽

Metal Elements ◽

Short Period

A heat transfer model for vaporizing in vacuum electron beam welding on magnesium alloy is developed based on the laws of heat conduction and energy conservation. The vaporizing time of the main metal elements in AZ series magnesium alloy is calculated using the model. The results show that the vaporization of Mg element will precede the Zn element under the affecting of high energy density electron beam. The vaporizing times of alloying elements are not entirely dependent on the level of the boiling point, to a certain extent, also dependent on the thermal diffusivity and are closely related to the latent heat of vaporizing and melting of the materials. The change of beam spot diameter of electron beam also greatly alters the heat transfer characteristics of electron beam heat source beam. As the strong vaporizing effect of Mg element will occur within several milliseconds, the keyhole induced by the metal elements vaporizing is formed only within several milliseconds, but also the deep penetration welding effect of vacuum electron beam welding of magnesium alloys will be obtained in a very short period of time.

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Experimental Evaluation and Characterization of Electron Beam Welding of 2219 AL-Alloy

Indian Journal of Materials Science ◽

10.1155/2016/5671532 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Mohamed Sobih ◽

Zuhair Elseddig ◽

Khalid Almazy ◽

Mohamed Sallam

Keyword(s):

Electron Beam ◽

Aluminum Alloys ◽

Weld Joint ◽

Electron Beam Welding ◽

High Energy ◽

High Energy Density ◽

Welding Parameters ◽

Deep Penetration ◽

Al Alloy ◽

Aircraft Industry

Aiming to reduce the weight of components, thus allowing a profit in terms of energy saving, automotive industry as well as aircraft industry extensively uses aluminum alloys. The most widely used joining technology in aircraft industry is riveting, while welding seems to be used in the car industry in the case of aluminum alloys. However, welding technology is characterized by many defects, such as gas porosity; oxide inclusions; solidification cracking (hot tearing); and reduced strength in both the weld and the heat affected zones which could limit its development. Many techniques are used for aluminum alloys welding, among them is electron beam welding (EBW), which has unique advantages over other traditional fusion welding methods due to high-energy density, deep penetration, large depth-to-width ratio, and small heat affected zone. The welding parameters that yield to optimal weld joint have been previously obtained. These optimal parameters were validated by welding a specimen using these parameters. To evaluate this optimal weld joint, complete, microstructural observations and characterization have been carried out using scanning electron microscopy, optical microscopy, and energy dispersive X-ray analysis. This evaluation leads to description and quantification of the solidification process within this weld joint.

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Digital Filament Power Supply Designed for Electron Beam Welder

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.392.382 ◽

2013 ◽

Vol 392 ◽

pp. 382-385

Author(s):

Ze Ting Wang ◽

Peng Wang ◽

Sheng Wen Fan ◽

Tao Chen

Keyword(s):

Electron Beam ◽

Power Supply ◽

Electron Beam Welding ◽

High Volume ◽

High Energy ◽

High Energy Density ◽

Soft Start ◽

Control Scheme ◽

Power Frequency ◽

Low Efficiency

The electron beam welding has high energy density, and the advantages of small welding deformation, in the defense, automotive, shipbuilding, precision machinery and other industries has been widely applied. Traditional electron beam welding machine power supply system adopts the technology of the power frequency or medium frequency, high volume, low efficiency and poor stability of electron beam. Combining with the characteristics of electron beam welding power source and the existing shortcomings, I put forward a digital filament power control scheme based on STM32, and introduce the hardware and software implementation method in detail. Experiments show that it can realize soft-start and soft-down process, and also be quickly identified and promptly forbid the output when filament fracture, which realize the intellectualization of filament power supply.

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The Evaporation Effect of Front Keyhole Wall in Penetration Welding with an Electron Beam

Materials Science Forum ◽

10.4028/www.scientific.net/msf.686.355 ◽

2011 ◽

Vol 686 ◽

pp. 355-360 ◽

Cited By ~ 4

Author(s):

Yi Luo ◽

Jin He Liu ◽

Chang Hua Du ◽

Hui Bin Xu ◽

Chun Tian Li

Keyword(s):

Heat Transfer ◽

Electron Beam ◽

Magnesium Alloy ◽

Electron Beam Welding ◽

Process Condition ◽

High Energy ◽

High Energy Density ◽

Deep Penetration ◽

Heat Transfer Theory ◽

Keyhole Effect

The process of vacuum electron beam welding is characterized by deep-penetration with the action of keyhole effect. The assumption of simple cylindrical physical model of keyhole is reasonable according to the thermal transfer of the keyhole effect during welding. There is an intensive evaporation arises from the front keyhole wall owing to the high energy density of electron beam. Therefore, an analysis model of heat transfer at the interface of vapor phase and front keyhole wall was proposed to the temperature calculation on the basis of heat transfer theory. The evaporation of the primary elements, which are Mg, Al, Zn and Mn in AZ series magnesium alloy, can be analyzed by the model, as well as the influence of keyhole radius varying on the temperature at vapor-solid interface offront keyhole wall. And dimensionless parameters are introduced to analyze the influence of the process condition on the thermal effect. The calculation results show that Mg and Zn are vulnerable to vaporize loss during the vacuum electron beam welding on AZ series magnesium alloy, and the evaporation of Mg occurs earlier than Zn. A longer electron beam acting duration and smaller keyhole size will increase the temperature of the front keyhole wall significantly, which has a considerable influence on the evaporation effect of the elements.

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Thermally Induced Reduction of Hot Cracking Susceptibility in Electron Beam Welding of CuCr1Zr: A Numerical Approach

10.21203/rs.3.rs-783812/v1 ◽

2021 ◽

Author(s):

R. Chin ◽

P. S. Effertz ◽

I. Pires ◽

N. Enzinger

Keyword(s):

Electron Beam ◽

Heat Source ◽

Electron Beam Welding ◽

Welding Process ◽

Numerical Approach ◽

Hot Cracking ◽

Solidification Cracking ◽

Additional Heat ◽

Residual Stress State ◽

Parameter Configuration

Abstract Electron Beam Welding (EBW) is a highly effective and accurate welding process that is being increasingly used in industrial work and is of growing importance in manufacturing. In the current study, solidification cracking in EBW of a CuCr1Zr cylindrical geometry was explored. To investigate and prevent occurrence of hot cracking, a thermomechanically coupled numerical model was developed using Finite Element Method (FEM). An additional heat source was considered, in order to influence the resulting residual stress state, namely to minimize tensile stresses in the fusion zone during solidification. Hence, a methodical assessment of relevant parameters, such as the power, the diameter of the additional heat source and the distances between both heat sources was employed using Design of Experiments (DoE). It was found that for a particular parameter configuration, solidification cracking most likely could be averted.

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Effect of the temperature gradient on hot cracking susceptibility for electron beam welding Alloy 247 LC

Materials Testing ◽

10.3139/120.111538 ◽

2020 ◽

Vol 62 (7) ◽

pp. 721-726 ◽

Cited By ~ 1

Author(s):

Aleksej Senger ◽

Torsten Jokisch ◽

Simon Olschok ◽

Uwe Reisgen

Keyword(s):

Electron Beam ◽

Temperature Gradient ◽

Electron Beam Welding ◽

Hot Cracking ◽

Welding Alloy

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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

Modern Physics Letters B ◽

10.1142/s0217984920500566 ◽

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.

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