Phase-field study on microstructure formation in Mar-M247 during electron beam welding and correlation to hot cracking susceptibility

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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Influence of electron beam welding parameters on the weld seam geometry of Inconel 718 at low feed rates

Materials Testing ◽

10.1515/mt-2020-621211 ◽

2020 ◽

Vol 62 (12) ◽

pp. 1221-1227

Author(s):

Julius Raute ◽

Torsten Jokisch ◽

Angelina Marko ◽

Max Biegler ◽

Michael Rethmeier

Keyword(s):

Electron Beam ◽

Inconel 718 ◽

Weld Seam ◽

Electron Beam Welding ◽

Development Stage ◽

Industrial Applications ◽

Hot Cracking ◽

Welding Parameters ◽

Thick Sheet ◽

Significant Difference

Abstract Ni-based superalloys are well established in various industrial applications, because of their excellent mechanical properties and corrosion resistance at high temperatures. Despite the high development stage and a common industrial use of these alloys, hot cracking remains a major challenge limiting the weldability of the materials. As commonly known, the hot cracking susceptibility during welding increases with the amount of precipitation phases. Hence, a large amount of highstrength Ni-Alloys is rated as non-weldable. A new approach based on electron beam welding at low feed rates shows great potential for reducing the hot cracking tendency of precipitation-hardened alloys. However, geometry and properties of the weld seam differ significantly in comparison to the common process range for practical uses. The aim of this study is to investigate the influence of welding parameters on the seam geometry at low feed rates between 1 mm/s and 10 mm/s. For this purpose, 25 bead on plate welds on a 12 mm thick sheet made of Inconel 718 are carried out. First, the relevant parameters are identified by performing a screening. Then the effects discovered are further studied by using a central composite design. The results show a significant difference between the analyzed weld seam geometry in comparison to the well-known appearance of electron beam welded seams.

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

Materials Testing ◽

10.1515/mt-2020-620710 ◽

2020 ◽

Vol 62 (7) ◽

pp. 721-726 ◽

Cited By ~ 1

Author(s):

A. Senger ◽

T. Jokisch ◽

S. Olschok ◽

U. Reisgen

Keyword(s):

Electron Beam ◽

Temperature Gradient ◽

Electron Beam Welding ◽

Rupture Strength ◽

Cast Alloy ◽

Welding Process ◽

High Energy ◽

Hot Cracking ◽

High Energy Density ◽

Welding Parameter

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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