A study was undertaken to describe the effects of various annealing treatments, both intercritical and supercritical, on the mechanical properties and microstructures of six dual-phase, manganese-silicon, manganese-silicon-chromium (Mn-Si-Cr), manganese-silicon-molybdenum, and manganese-silicon-vanadium (Mn-Si-V) steels having nearly equal hardenability. Results indicate that the combination of tensile strength and total elongation after intercritical treatments is slightly better than after supercritical treatments. Although hardenabilities of the alloys are more or less equal, it appears that the strength-ductility relationship varies a little with chemistry. The strength-ductility behavior of Mn-Si-Cr steels compares quite favorably with that of commercial Mn-Si-V steels with optimum processing conditions for both. It was confirmed that the tensile strength of dual-phase steels is primarily a function of the hard-phase (mainly martensite and bainite, if any) content at a given ferrite grain size. The full curve "n" (strain hardening exponent) values of the six alloys are higher than the uniform true strain "n" values. The observed variations of uniform true strain "n" values with volume fraction hard-phase content are satisfactorily explained in terms of the Araki et al. theory (1977). On the other hand, full curve "n" values follow those predicted by the Davies-Mileiko theory (1978). The minimum amount of hard-phase content needed for the elimination of yield point elongation in these alloys varied from one alloy to the other.

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  • Supplemental Notes:
    • Presented at SAE Congress and Exposition, Detroit, 26 February-2 March 1979.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Aichbhaumik, D
    • Goodhart, R R
  • Publication Date: 1979

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Filing Info

  • Accession Number: 00394087
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 790010, HS-026 876U
  • Files: HSL, USDOT
  • Created Date: May 31 1985 12:00AM