WELDING CHARACTERISTICS OF COMMERCIAL COLUMBIUM ALLOYS

Journal Article · Fri Feb 01 04:00:00 EST 1963 · Welding J. (N.Y.)

OSTI ID:4711500

Gerken, J M; Faulkner, J M

The welding characteristics of three commercial Nb-base alloys (FS82, D31, and F48) were investigated. Both gas tungsten-arc and electron beam welding were included. Welds were evaiuated for bend ductility transition temperature, hardness, tensile strength, and microstructure. The effects of travei speed, shielding gas composition and purity, filler metal additions, preheat, and postheat were investigated. Gas tungsten-arc welding was performed in a vacuum purge atmosphere chamber; however, for comparison, some welds were made without the use of a chamber but with careful back shielding and traiier shielding. Thermal cycles were measured in the fusion and heat, affected zones of gas tungsten-arc welds to help explain mechanicai properties and microstructure on the basis of physical metallurgy of each alloy. The most significant effect of welding on all alloys investigated was the lowering of ductility or increasing the ductile to brittle transition temperature. Postweld aging studies were conducted on FS82 alloy welds to determine the effect on ductility. Electron micrographs of the heat-affected zone and fusion zone indicate that the loss of ductility is caused by an aging reaction and that ductllity is regained as overaging takes place. Electron beam welds in D31 and F48 were signiftcantly more ductile than gas tungsten-arc welds in these alloys. It is believed that ductility is lowered in welds in these materials by solution of an embrittling phase follow by precipiiation during the weld thermal cycle. The smaller loss in ductility associated with electron beam welding may be the result of two factors-- -a higher purity weld puddle provided by the vacuum environment and a much shorter time the weld was at elevated temperature. (P.C.H.)

• Research Organization: Thompson Ramo Wooldridge Inc., Cleveland
• NSA Number: NSA-17-011243
• OSTI ID: 4711500
• Journal Information: Welding J. (N.Y.), Journal Name: Welding J. (N.Y.) Vol. Vol: 42
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS