美国进口INCONEL718SPF合金棒英科乃尔718SPF无缝管

进口INCONEL 718SPF合金棒英科乃尔718SPF无缝管
INCONEL 718SPF
牌号:Inconel 718SPF
C(％):≤0.05
Si(％):≤0.35
Mn(％):≤0.35
Cr(％):17.0～21.0
Ni(％):50.0～55.0
Mo(％):2.80～3.30
Co(％):≤1.00
W(％):—
Al(％):0.20～0.80
Cu(％):≤0.30
Ti(％):0.65～1.15
Fe(％):余量
其他(％):Nb 4.75～5.25,B≤0.006,N≤0.01,P≤0.015,S≤0.015
INCONEL?alloy 718SPFTMis a specifically “tailored”version of INCONELalloy 718, designed for the super-plastic forming process. The alloy is optimized for theprocess by rigorous control of composition, melt prac-tice and rolling conditions. INCONELalloy 718SPF was developed to meet theneed for a nickel-base alloy suitable for manufactureinto complex shaped components subject to a combina-tion of high temperature, high temperature corrosionand high stress. INCONELalloy 718SPF meets all themechanical property requirements of AMS 5596G, asannealed plus aged, as well as all requirements of AMS5950, which is specific to INCONELalloy 718SPF.Superplastic forming, now highly sophisticated andused extensively for producing commercial and militaryaircraft components, is an ideal process for manufactur-ing complex shaped parts. Use of superplastic formingcan enhance component performance and reliabilitywhile lowering overall manufacturing cost by reducingthe need for extensive welding or other joining meth-ods, lowering the inventory of parts and simplifying themanufacturing process
INCONELalloy 718SPF has the same composition andphysical properties as INCONELalloy 718. Limitingchemical composition is shown in Table
1; physicalconstants in Table
2; and elastic properties as a functionof temperature in Tables 3 and 4 on page
3. Thermaland electrical properties are listed in Tables 5 to 7. Thedata in Tables 2 to 7 are typical and can vary slightly,depending on the composition and condition of the testspecimen.
INCONELalloy 718SPF is produced with an annealed tem-per. Typical annealed and annealed plus aged properties arepresented in Table 8. The effect of varying gauge on stressrupture life is presented in Table 9 for two aging conditions.The alloy is produced to a grain size of ASTM No. 10 (0.01mm/0.0004 in) or finer. As produced, INCONELalloy718SPF sheet meets the strength and ductility requirementsof AMS 5596G, as annealed plus aged. Table 10 presents data on the tension-tension fatigue-resistance of INCONELalloy 718SPF (ASTM grain size#13), and compares the results with those for conventional-ly produced alloy 718 (ASTM grain size #4.5) in similar testconditions. The axial fatigue testing was carried out at a fre-quency of 59 Hz.
INCONELalloy 718SPF possesses two essential character-istics that make the alloy amenable to superplastic forming:Grain size stability over the time and temperature
regime employed for superplastic forming (See Figure 1).Acombination of low flow stress and significant ductility using typical superplastic forming process conditions (See Figure 2).The effect of lower temperatures on flow stress and totalengineering strain at constant strain rate is depicted in Figure3. For the typical initial strain rates currently employed forsuperplastic forming, the expected range of engineeringstrain for INCONELalloy 718SPF is given in Figure 4. Theeffect of lower temperatures on the engineering strain as afunction of the initial strain rate is shown in Figure 5. Forthe same initial strain rates, the expected true stresses forINCONELalloy 718SPF are given in Figure 6 and for lowertemperatures in Figure 7.
The superplastic forming process for INCONELalloy718SPF involves the shaping of sheet between ceramic ormetallic platens at temperatures near 1750°F (954°C). Thesheet is subjected to an inert gas pressure of about 300 psi(2.1 MPa) for periods up to four hours. Table 13 compares the annealed properties of INCONELalloy 718SPF with that of superplastic alloy formed materi-al with reductions in gauge of 13%, 19% and 33%. Notethat, under these conditions, the alloy exceeds the maximumannealed strength requirements of AMS 5596G but not theminimum requirements for ductility and hardness. This islargely due to the ultra-fine grain size of the material whichremains essentially constant during superplastic forming.While grain size remains constant, increasing deformationas a result of the superplastic forming process reduces hard-ness, tensile strength and elongation. Table 14 shows the effect of annealing time (0.33 and 1.0h) at 1750°F (954°C) on restoring aged room temperaturetensile ductility (the minimum elongation of AMS 5596G is12%). Tensile properties and hardness are satisfactory, asare all tensile properties at 1200°F (649°C) for the timesevaluated. Because of the fine grain size of the post-super-plastically formed material, it is not possible to achieve thestress rupture life of AMS 5596G without incorporating agrain growth annealing step prior to the aging heat treat-ment, as indicated in Table 15. HIPing (hot isostatic pro-cessing) of superplastically formed components may beespecially advantageous for enhancing stress rupture andfatigue properties.
Like most nickel alloys, INCONELalloy 718SPF is subjectto cavitation. As shown in Figure 10, the area of cavitation,while minimal at elongations of less than 150%, increasessignificantly with increasing elongations beyond 200%.Decreasing strain rates at any given elongation also increasethe area of cavitation. The area of cavitation for two initialstrain rates and total strains of less than 200% are presentedin Table 16 along with the average cavity size for each totalstrain. Use of background pressure during the superplastic form-ing operation is an effective method for reducing cavitation.Cavitation data as a function of maximum true strain andbackground pressure are presented in Figures 11 and 12 forinitial strain rates of 1 x 10-4s-1and 3 x 10-5s-1, respectively.Hot isostatic pressure exposure at 1750°F (954°C) and 15ksi (103 MPa) has been found to eliminate cavitation insuperplastically processed sheet that has been reduced 33%in thickness.