Characteristics of an autogenous single pass electron beam weld in thick gage CA6NM steel

  1. Get@NRC: Characteristics of an autogenous single pass electron beam weld in thick gage CA6NM steel (Opens in a new window)
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Journal titleInternational Journal of Advanced Manufacturing Technology
Pages15231535; # of pages: 13
SubjectCorrosion; Electron beam welding; Electron beams; Filler metals; Heat affected zone; Heat treatment; Low carbon steel; Martensitic stainless steel; Microhardness; Microstructure; Preheating; Welding; Welds; CA-6NM martensitic stainless steels; Defocused beams; High energy densities; Micro-structural characteristics; Microstructural variation; Post weld heat treatment; Pre-heat treatment; V-groove joints; Stainless steel
AbstractCA6NM is a low carbon martensitic stainless steel that is widely applied in hydroelectric turbine manufacturing. Using conventional fusion welding techniques, the fabrication of a thick section in CA6NM requires a V-groove joint design and multiple passes to achieve the required penetration. However, exposure to a substantial heat input through this process renders large fusion and heat-affected zones, microstructural variations, as well as distortion of the assembly, which pose difficulties for the manufacture and performance of the component. The application of a high energy density technique, namely electron beam (EB) welding, was used in the present work to penetrate a 60-mm-thick section in CA6NM with a single pass without filler metal. To prevent cracking in the weldment, the CA6NM was heated to 100–170 °C before EB welding using a zonal preheat treatment, which was applied in situ using a defocused beam. The as-welded CA6NM exhibited a narrow fusion zone (FZ) and a series of distinct yet very small heat-affected zones (HAZ) with different microstructural characteristics. As compared to the base metal (BM) hardness of 289 ± 4 HV, the EB weldment exhibited a hardness maximum of 425 HV in the HAZs and an average hardness of 395 ± 6 HV in the FZ. Post-weld heat treatment (PWHT) was effective in lowering the hardness in the FZ of the EB weldment to a mean value of 346 ± 13 HV.
Publication date
PublisherSpringer International Publishing
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace
Peer reviewedYes
NPARC number21275692
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Record identifierad2b8836-80a8-49f7-bf37-2cc7164d064c
Record created2015-07-14
Record modified2016-05-09
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