STP890

    Developments in Premium High-Strength Powder Metallurgy Alloys by Kaiser Aluminum

    Published: Jan 1986


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    Abstract

    Powder metallurgy (PM) development by the Kaiser Aluminum & Chemical Corp. began in 1953 with a U.S. Air Force contract to make high-modulus, high-temperature alloys. From 1957 to 1959, alloy supersaturation studies were undertaken on binary, ternary, and more complex alloys. The development of powder products with good room-temperature properties followed in 1959 to 1961. Some of the Al-Zn-Cu-Mg-based PM alloy extrusions had tensile yield strengths of > 760 MPa (> 110 ksi). In the late 1960s, the high-strength, heat-treatable 7XXX alloy PM61 was developed. In the early 1970s, an improved powder vacuum degassing method was developed, which removes essentially all of the volatile contaminants at lower temperatures and shorter times than required by previous vacuum degasification processes. Using this new degassing technology, PM61 alloy seat track extrusions were produced for use in Boeing 727 aircraft in 1977. Two new alloys, PM62 (a 7XXX type) and PM63 (a 2XXX type) were developed in 1976 and 1977; these alloys exceeded the minimum allowable strength levels of high-strength ingot metallurgy (IM) 2XXX and 7XXX alloy extrusions by about 30%. During 1978 and 1979, Alloy PM64, a 7XXX alloy having improved damage tolerance, was developed. A subsequent U.S. Navy contract with the Northrop Corp. showed that PM64 alloy extrusions exhibited a combination of properties superior to those of contemporary high-strength IM or PM alloys. Recently, slight chemistry and fabrication modifications of PM63 and PM64 alloys have produced significant improvements in fatigue crack growth resistance without adversely affecting other properties. It has also been demonstrated that PM64 alloy sheet has attractive superplastic properties.

    Keywords:

    aluminum alloys, powder metallurgy, aluminum powder metallurgy, Al-Zn-Mg-Cu (7XXX) alloys, Al-Mg-Cr alloy, 2XXX alloys, hot vacuum degassing, elevated-temperature aluminum alloys, extrusion, forgings, superplastic forming, Al-SiC composites, weldable PM aluminum alloys


    Author Information:

    Ping, SW
    Staff research engineer, Kaiser Aluminum & Chemical Corp. Center for Technology, Pleasanton, CA


    Paper ID: STP33040S

    Committee/Subcommittee: B09.09

    DOI: 10.1520/STP33040S


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