Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Modulus of Elasticity of steel at 1000degC 1
- Thread starter markeee
- Start date
-
1
- #2
CalvinKelly
Materials
Hooke's law is repealed above roughly 540C (1000F).
Above this temperature neither steel, stainless steel nor nickel base superalloys behave in an elastic manner. That is, stress is no longer proportional to strain. "Time-dependent properties" rule. For just about any stress level, the material will "creep", deform slowly with time. One cannot use elastic modulus data, even that which is published, to calculate a deflection from load. There will be an initial more-or-less elastic deflection, then that deflection will increase slowly with time. The creep rate (deflection rate) will depend upon stress and upon the strength of the material in question. The measure of strength in this range is either creep or time to rupture. Creep may be total creep, more commonly used in Europe, or minimum creep rate, commonly used in USA. More written discussions of this topic may be had from Special Metals, Huntington West Virginia, or Rolled Alloys, Michigan.
James Kelly
Above this temperature neither steel, stainless steel nor nickel base superalloys behave in an elastic manner. That is, stress is no longer proportional to strain. "Time-dependent properties" rule. For just about any stress level, the material will "creep", deform slowly with time. One cannot use elastic modulus data, even that which is published, to calculate a deflection from load. There will be an initial more-or-less elastic deflection, then that deflection will increase slowly with time. The creep rate (deflection rate) will depend upon stress and upon the strength of the material in question. The measure of strength in this range is either creep or time to rupture. Creep may be total creep, more commonly used in Europe, or minimum creep rate, commonly used in USA. More written discussions of this topic may be had from Special Metals, Huntington West Virginia, or Rolled Alloys, Michigan.
James Kelly
Modulus of elasticity has been determined for specific alloy steels and published by their manufacturer's at the alloy steels' maximum usable temperatures (generally less than 1350 F). The values are based on short term tensile testing and have little relevance to design per the reasons given by CalvinKelly above.
- Status
Similar threads
- Question
- Question
