The Biaxial Strengthening of Textured Titanium

Babel, H. W.; Eitman, D. A.; McIver, Robert W.

doi:10.1115/1.3609543

Cited by 14 publications

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“…As would be expected for 0.020-inch-(0.051-cm-) thick sheet, all specimen fractures As figure 6 shows, the difference in smooth and notch properties between the two alloys was slight. Additionally, directionality effects were minimal.…”

Section: Uniaxial Propertiessupporting

confidence: 48%

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Texture Strengthening and Fracture Toughness of Titanium Alloy Sheet at Room and Cryogenic Temperatures

Sullivan

1968

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SUMMARYPreferred crystallographic orientation or texturing in metallic sheet can, under conditions of biaxial stress, result in strengthening considerably greater than that predicted f o r a n isotropic material. Certain titanium alloys exhibit texturing. After it is rolled into sheet form, titanium alloyed with about 4 percent aluminum gives close to the ideal texture f o r maximum biaxial strengthening. The commercially available titanium alloy, Ti-5A1-2. 5Sn, also exhibits texture strengthening. The effect of texturing on the yield, ultimate, notch, and weld strengths of both Ti-4A1-0.20 and Ti-5A1-2.5Sn extra-lowinterstitial (ELI) grade was determined by testing 0.020-inch-(0.051-cm-) thick sheet in uniaxial and 1 to 2 biaxial stress fields at 20°, 77' , and 294' K. The biaxial test specimens were cylinders 6 inches (15.2 cm) in diameter and 18 inches (45.7 cm) long.In addition, plastic Poisson's ratios were determined at the three test temperatures.The ratio of 1 to 2 biaxial to uniaxial yield strength ranged from 1. 36 at 20' K to 1.53 at 294' K for the Ti-4A1-0.20 alloy (room-temperature plastic Poisson's ratio 0.845) and f r o m 1.24 at 20' K to 1. 37 at 294' K for the Ti-5A1-2.5Sn ELI alloy (room temperature p 0.732). Substantial increases in ultimate strength were also obtained. Although the Ti-4A1-0.20 alloy had less uniaxial strength than did the Ti-5A1-2.5Sn ELI alloy, its more heavily textured condition generally resulted in greater 1 to 2 biaxial strength.strength. Tests of through-cracked cylinders at 20' and 77' K showed the Ti-4A1-0.20 alloy to have greater notch sensitivity. However, f o r through cracks 0.10 inch (0.25 cm) o r less, the 1 to 2 biaxial notch strengths of the two alloys are about equal. The use of plastic Poisson's ratio to predict the increase in biaxial yield strength resulted in good agreement with experimental values. pP7 P'The Ti-4A1-0.20 alloy a l s o exhibited superior biaxial weld INTRO D UCT IONCertain anisotropy in sheet materials can cause appreciable strengthening under conditions of biaxial stress. The form of anisotropy r e f e r r e d to is called texturing and is characterized by isotropy in the plane of the sheet with considerable anisotropy normal to this plane. For the purely isotropic case, yielding in a 1 to 2 stress field is predicted to occur at 1.15 times the uniaxial yield strength. For textured materials, however, yield strengths 1 . 5 times uniaxial yield strength or greater have been predicted for the same s t r e s s field (ref. 1). Uniaxial studies of texturing in titanium alloys have been made by several investigators (refs. 2 to 4). Sliney, e t al. (ref. 5) and Babel, et al. (ref. 6) have experimentally investigated the biaxial strengthening of Ti-5A1-2.5Sn alloy cylindrical p r e s s u r e vessels at room temperature. This work r e p o r t s the r e s u l t s of a n investigation of biaxial strengthening in a n experimental textured titanium alloy, Ti-4A1-0.20, at temperatures as low as 20' K.of the hexagonal close-picked crystals are parall...

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Section: Uniaxial Propertiessupporting

confidence: 48%

“…Average smooth and notch properties f o r both alloys a r e plotted as a function of test temperature in figure 6. Specimens were tested with the loading direction both parallel (longitudinal specimen) and normal (transverse specimen) to the rolling direction.…”

Section: Uniaxial Propertiesmentioning

confidence: 99%

Texture Strengthening and Fracture Toughness of Titanium Alloy Sheet at Room and Cryogenic Temperatures

Sullivan

1968

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“…Figure 2 shows a biaxial-ultimate-strength envelope for two materials, each having the same value of the strain-hardening exponent (n=0.095) : One material is isotropic (a=1) and the other is of the texture-hardening type with a = 1.36. The transitional biaxialstress ratio at which the plastic tensile instability phenomenon changes from hoop to axial (shown as dashed lines in Figure 2) is found by equating Sai = BSoi, using values from (8) and (23) for Soi and Sai, respectively. The result is:…”

mentioning

confidence: 99%

“…The ratios a and R are related by the following expression: Table 1 lists values of R, J-tp, and a determined experimentally for some titanium alloys [6,8,9,24,26,27,34]. (27).…”

mentioning

confidence: 99%