Microstructure of Al-Li Alloy Electron Beam Welding Joint after Post-Weld Heat Treatment

2012 ◽  
Vol 217-219 ◽  
pp. 1921-1927 ◽  
Author(s):  
Shao Gang Wang ◽  
Kuang Yu ◽  
Chuan Xiao Luo ◽  
Li Xing
Keyword(s):  
Heat Treatment ◽  
Electron Beam ◽  
Grain Boundary ◽  
Electron Beam Welding ◽  
Grain Morphology ◽  
Post Weld Heat Treatment ◽  
Joint Fracture ◽  
Δ Phase ◽  
Strengthening Phases ◽  
Weld Heat

Heat treatment was carried out to the 1420 Al-Li alloy electron beam welding (EBW) joints after welding, and the microstructures of welded joints are analyzed systematically before and after post-weld heat treatment (PWHT). The observation of joint microstructure demonstrates that the grain morphology of weldment changes from equiaxed dendrites in as-welded (AW) condition into equiaxed grains after PWHT, and that the fine strengthening phases precipitate within the grain. The XRD analysis of phase constituent and TEM observation of weldment indicate that the main strengthening phases in 1420 Al-Li alloy weldment are spheroidal δ′(Al3Li), β′(Al3Zr) and rod-like T(Al2MgLi) after PWHT. Furthermore, the δ′ phase precipitate free zone (PFZ) is found along the grain boundary. The scanning observation of joint fracture shows that Al-Li alloy EBW joint presents the characteristic of transgranular ductile fracture in AW condition. After PWHT, the Al-Li alloy welded joint presents the pattern of intergranular fracture. The variation of fracture mode is related to dispersed precipitation of δ′ phase and the formation of PFZ at the grain boundary in weldment after heat treatment.

scholarly journals Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel

10.30544/545 ◽  
2020 ◽  
Vol 26 (3) ◽  
pp. 279-292
Author(s):  
Akash Doomra ◽  
Sandeep Singh Sandhu ◽  
Beant Singh
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Electron Beam ◽  
Ferritic Stainless Steel ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The applicability of ferritic stainless steel is restricted due to its low weldability, and this can be attributed to the severe grain growth in the weld zone during the solidification of the weld pool and formation of fully ferritic structure. This study aims to investigate the weldability of 18 mm thick AISI 409 ferritic stainless steel plates using an electron beam welding process without the use of filler metal. The joints were investigated for metallography characterization (microstructure, macrostructure, and microhardness) and mechanical behavior (tensile strength and impact toughness) in as-welded condition and after post-weld heat treatment at 550 ºC for 75 minutes. The weld zone exhibited large columnar grains in the direction perpendicular to the weld centerline and got refined after post-weld heat treatment. The ultimate tensile strength, yield strength, and microhardness of the weld zone were found higher than the base metal. The impact toughness of weld zone was found to be reduced by 45%, but the post-weld heat treatment improved the toughness by 40%. Results revealed that the electron beam welding process could be successfully employed for welding of AISI 409 ferritic stainless steel, which will increase its application range that requires thicker section of welded plates. Post-weld heat treatment was found to be advantageous for improving the microstructure and mechanical properties.

Weldability Studies of AISI 409 Ferritic Stainless Steel Thick Plates Using Electron Beam Welding Process

2021 ◽  
Vol 11 (2) ◽  
pp. 55-67
Author(s):  
Akash Doomra ◽  
Beant Singh ◽  
Sandeep Singh Sandhu
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Electron Beam ◽  
Impact Toughness ◽  
Base Metal ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

In the present research, attempts have been made to weld 18 mm thick AISI 409 ferritic steel plate in a single pass with electron beam welding process. The welded joint was investigated for macrostructure, microstructural, microhardness, impact toughness, and tensile strength. The coarse ferritic grains of base metal were converted into fine equiaxed and columnar grains in the weld zone. The microhardness results revealed that for fusion zone and heat affected zone had 28% and 41% higher microhardness than the base metal. Further, post weld heat treatment at 550ºC/75 minutes resulted in 5% rise in ultimate tensile strength, 10% rise in yield strength, and 31% rise in impact toughness as compared to as welded specimens. The fractography of impact and tensile specimens revealed brittle mode of fracture and changed to ductile mode after post weld heat treatment.

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