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Alloy X-750

  • Material

    UNS N07750,Alloy X-750,W.Nr.2.4669, GH4145

  • Overview

    Alloy X-750 is a precipitation-hardenable nickel-chromium alloy used for its corrosion and oxidation resistance and high strength at temperatures to 1300°F. Although much of the effect of precipitation hardening is lost with increasing temperature over 1300°F, heat-treated material has useful strength up to 1800°F. Alloy X-750 also has excellent properties down to cryogenic temperatures.

  • Characteristics

    Alloy X-750 Characterized by:

    ◇ high tensile strength up to 705°C (1300°F)

    ◇ high creep and rupture strength up to 820 °C (1500 °F)

    ◇ high oxidation resistance up to 980 °C (1800 °F)

    ◇ excellent mechanical properties in cryogenic environments

    ◇ good corrosion resistance at high and low temperatures and high resistance to stress corrosion cracking

    ◇ good weldability by resistance and fusion processes

  • Application

    The economics of alloy X-750 coupled with its availability in all standard mill forms has resulted in applications in a wide variety of industrial fields. In gas turbines, it is used for rotor blades and wheels, bolts, and other structural members. Alloy X-750 is used extensively in rocket-engine thrust chambers. Airframe applications include thrust reversers and hot-air ducting systems. Large pressure vessels are formed from alloy X-750. Other applications are heat-treating fixtures, forming tools, extrusion dies, and test machine grips. For springs and fasteners, alloy X-750 is used from sub-zero to 1200°F.

    Depending on the application and the properties desired, various heat treatments are employed. For service above 1100°F, particularly where loads are to be sustained for long times, optimum properties are achieved by solution treating (2100°F) plus stabilization treating (1550°F) plus precipitation treating (1300°F). For service below 1100°F, the alloy may be strengthened by precipitation treating after hot or cold working or by precipitation treating after equalizing or solution treating. A furnace-cooling treatment is also used to develop optimum properties for some applications.

    Due to its high temperature strength up to 820 °C (1500 °F) and its excellent corrosion resistance, Alloy X-750 finds a wide range of applications.

  • Chemical Composition (wt%)








    Alloy X-750














    Alloy X-750







  • Mechanical Property (AMS 5582)

    Tensile strength

    ksi (MPa)

    Yield strength at

    0.2 offset ksi (MPa)

    Elongation in 2” 

    % min.

    Rupture life (1350°F/45 ksi)

    155 (1069)

    100 (690)

    15 (strip specimen)

    20 (full tube)

    23 hours

  • Corrosion Resistance

    Alloy X-750 is resistant to a wide variety of industrial corrosives under both oxidizing and reducing conditions. It resists oxidation and attack by other high-temperature corrosion mechanisms.

    In hot corrosion tests for automotive applications, weight loss after exposure for 100 hours in 90% Na2SO4 + 10% NaCl mixture in air was about 5%. Samples precoated with sodium chloride (by dipping in a hot saturated salt solution), suspended in a furnace at 1700°F and exposed for 100 hr to a moving gas stream of air containing 1% SO2 exhibited a corrosion penetration of approximately 0.007 in. An interesting feature of this alloy is its high resistance to chloride-ion stress-corrosion cracking even in the fully precipitation-hardened condition. Standard U-bend specimens of precipitation-hardened material (hardness, 33 Rc) showed no signs of cracking when exposed to boiling 42% magnesium chloride for 30 days.

  • Heat Treatment

    The heat treatment described by AMS Specification 5582

    For high strength to 1300°F, Alloy X-750 seamless tubing (cold-drawn, annealed) is given the following precipitation treatment: 1300°F/20 hr, A.C.

  • Available Process

    (1) Hot formed, solution annealed, descaled

    (2) Cold worked and bright annealed

    (3) Cold worked, annealed and descaled

    (4) Cold worked, polished (MP, EP etc.)

    (5) Cold worked, bright annealed, polished (MP, EP etc.)

  • Common Tests

    Chemical composition






    Micro structure



    Intergranular Corrosion

    Surface condition

    Shape and dimension

    Positive Material Identification

  • Product Forms


    Size range

    Capillary tube

    OD 0.08 ~ 6.0 mm

    WT 0.015 ~ 1.5 mm

    Thin wall & Ultra thin wall seamless tube

    OD6.0 ~80.0 mm

    WT 0.05 ~4.5 mm

    Micro ID and heavy thick wall seamless tube

    OD3.0 ~50.0 mm

    ID 0.30 ~5.0 mm

    Precision conic seamless tube

    Bigger end: OD3.0 - 426.0mm

    Smaller end: OD2.5 - 346.0mm

    WT: 0.15 - 40.0mm

    HP /UHP BA+ tube

    EP tube

    OD 1.0 ~ 76 mm

    WT 0.10 ~ 10.0 mm

    Small caliber precision seamless tube

    OD6.0 ~89 mm

    WT 0.50 ~9.0 mm

    Profiled seamless tube

    Build to drawing

    Build to specification

    Bourdon tube

    Y40, Y50, Y60, Y70, Y100, Y150

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