Development of multiple-beam techniques for electron beam welding of thick-walled components of duplex stainless steels without filler material

摘要

Electron beam welding is especially suited to produce joints of thick-walled components. The high power density of the electron beam allows welds with a depth/width ratio up to 200:1 which can be produced in one pass. In case of electron beam welding of duplex stainless steels the characteristic high cooling rate associated with this welding method induces an unfavorable ferrite content in the weld metal, with the consequent degradation of the mechanical properties and the corrosion resistance. The usage of the multiple-beam techniques can have a significant effect on the cooling rate in the temperature range between 1200 and 800℃ in which the diffusion controlled transformation from ferrite to austenite occurs. To avoid the high ferrite content in the weld the different multiple-beam techniques with the aim to achieve slower cooling rates from 1200 to 800℃ have been investigated. The development and the programming of these techniques as well as the results of electron beam welding duplex stainless steel X2CrNiMoN22-5-3 (material IDN 1.4462) using these methods are presented and discussed in this article.