THE CRYOGENIC AND ELEVATED TEMPERATURE PROPERTIES OF "SUPER ALPHA" TITANIUMALLOY WELDMENTS

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

OSTI ID:4749736

Mitchell, D R; Day, D L

Good welded properties were exhibited by all three of the advanced titanium-base sheet alloys with Ti-8Al- 1Mo- 1V and Ti-7Al-12Zr developing 10 to 15 ksi higher strength than Ti-5A1-5Sn-5Zr. Welded strengths were nearly equal to or surpassed the strength of the corresponding base metal. As-welded minimum bend radii were 4.0 to 6.0 T; tensile and bend ductility levels were moderately improved by postweld stress relief or annealing treatments. Weld strengths comparable to those of the base material were also observed at 800 and 1000 deg F, i.e., Ti-8Al- 1Mo- 1V and Ti-7Al- 12Zr developed higher strengths than Ti5A1- 5Sn-5Zr. Good stability was obtained in as-welded sheet of the three compositions as creep exposed at 800 deg F. However, some deterioration of tensile elongation was noted after creep exposure at 1000 deg F, particularly in Ti8Al- 1Mo- 1V and Ti-7Al- 12Zr. Postweld duplex annealing at 1800 to 1850 deg F (5 miN ac + 1100 deg F (8 hr) markedly improved the stability of Ti-8Al- 1Mo- 1V, but annealing at 1660 deg F had little or no effect on the stability of welded Ti- 5Al-5Sn-5Zr and Ti-7Al- 12Zr. Creep resistance of as-welded Ti-8Al- 1Mo-- 1V sheet was superior to that of the mill annealed base metal and was as good as or better than duplex annealed base metal. Thus, an improved combination of creep properties in the weld zone and adjacent base metal would be obtained by welding duplex annealed sheet or by duplex annealing after the welding operation. Resistance to creep of as-welded Ti-5A1-5Sn-5Zr and Ti-7Al- 12Zr was comparable to that of the 1350 deg F (8 hr) mill annealed base metal; welded and unwelded creep properties were both greatly enhanced by annealing at 1650 deg F. However, the incomplete stress relieving treatment of 1100 deg F (1 hr) ac offered no improvement in welded creep resistance and stability of Ti-5Al-5Sn-5Zr and Ti- 7Al12Zr. Subzero temperature notch tensile strengths of welded and unwelded Ti- 8Al- 1Mo- 1V exceeded the corresponding unnotched values at temperatures as low as -300 to -320 deg F using theoretical stress concentration factors (K/sub t/) of 3.0 and 6.0. Subsequent duplex annealing of both welded and 1350 deg F mill annealed base Ti- SAl- 1Mo- 1V improved the subzero temperature notch properties, particularly in the base metal, at a sharper notch of K/sub t/ = 8.0. Higher unnotched ductility and notch strength ratios were measured at subzero temperatures in 1650 deg F annealed Ti5Al-5Sn-52r unwelded sheet, compared to Ti- 7Al- 12Zr. In the as-welded condition, however, the low-temperature characteristics of the two alloys were similar except for the lower unnotched tensile elongation of Ti- 7Al- 12Zr. Postweld annealing at 1650 deg F improved the notch behavior and ductility of Ti-5A1-5Sn-5Zr; however, it had little beneficial influence on welded Ti--7Al- 12Zr except for higher tensile elongation. Of the three alloys, Ti-8Al1Mo-- 1V and Ti-5A1-5Sn-5Zr provided better cryogenic properties than Ti-7Al- 12Zr. As measured by the relaxation of restrained base metal bend specimens, complete stress relief of all three alloys was achieved in short practical periods (5 hr or less) only by using higher temperatures of 1100 to 1300 deg F. Compared to treatments at 1100 or 1200 deg F, stress relief annealing at 1300 deg F (1/2 to 3/4 hr) ac produced somewhat better weld ductility at strengths commensurate with those of the base metal. However, in the case of duplex annealed Ti- 8Al- 1Mo- 1V, this cycle would provide lower base metal creep resistance than if a 1100 deg F postweld stress-relieving treatment were used. (auth)

• Research Organization: Titanium Metals Corp. of America, Toronto, Ohio
• NSA Number: NSA-17-014886
• OSTI ID: 4749736
• Journal Information: Welding J. (N.Y.), Vol. Vol: 42; Other Information: Orig. Receipt Date: 31-DEC-63
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ALUMINUM ALLOYS
ANNEALING
CREEP
CRYOGENICS
DIFFUSION LENGTH
DUCTILITY
HIGH TEMPERATURE
LOW TEMPERATURE
MEASURED VALUES
MOLYBDENUM ALLOYS
NOTCHES
RELAXATION
SHEETS
STABILITY
STRESSES
TEMPERATURE
TENSILE PROPERTIES
TITANIUM ALLOYS
VANADIUM ALLOYS
WELDING
WELDS
ZIRCONIUM ALLOYS