THE FUNDAMENTAL FACTORS INFLUENCING THE BEHAVIOR OF WELDED STRUCTURES: THE EFFECT OF SUBCRITICAL HEAT TREATMENT ON THE TRANSITION TEMPERATURE OF A LOW CARBON SHIP PLATE STEEL AND SUPPLEMENT ON EMBRITTLEMENT OF "C" STEEL BY NITROGEN

The dependence of transition temperature upon subcritical heat treatment has been investigated in a low carbon ship plate steel (Project Steel "C"). The effect of time at temperature in the 700 deg--1200 deg F range has been determined, employing three different cooling rates--air cool, furnace cool, water quench. In addition, a limited study was made of the room temperature and the accelerated aging effects after water quenching from 1200 deg F. The degree of embrittlement was evaluated by means of eccentric notch tensile and Charpy V-notch impact tests, with the as-received plate as a basis of comparison. No change in microstructure could be noted between the subcritically treated specimens and the as-received plate with these exceptions: (1) a general precipitation was evident after accelerated aging, and (2) slight spheroidization was apparent at the long isothermal times. Rockwell B hardness tests showed that, in general, appreciable hardening occurred when specimens were embrittled. Previous work on welded plate showed that the necessary conditions for quench-aging are present in the welded material and this phenomenon appears to be the only possible explanation for the zone of minimum ductility located in a region adjacent to the weld which was not heated above the lower critical temperature. Cooling rate curves are presented for the critical zone in weldments made with various preheat temperatures to show that not only does the embrittlement increase with increasing cooling rate, but that the degree of embrittlement is about the same for the critical zone in weldments as for subcritically heat treated base plate cooled at the same rate from the same temperature.

  • Corporate Authors:

    Case Western Reserve University

    Department of Civil Engineering
    10900 Euclid Avenue
    Cleveland, OH  USA  44106

    Ship Structure Committee

    National Academy of Science, 2101 Constitution Avenue, NW
    Washington, DC  USA  20418
  • Authors:
    • Evans, E B
    • Klingler, L J
  • Publication Date: 1953-10-30

Media Info

  • Features: References;
  • Pagination: 87 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00331004
  • Record Type: Publication
  • Source Agency: Ship Structure Committee
  • Report/Paper Numbers: SSC- 60 Prog Rpt.
  • Contract Numbers: NObs-45470
  • Files: TRIS
  • Created Date: May 21 1981 12:00AM