CAST LOW-TEMPERATURE STEEL

To obtain sufficiently low brittle threshold temperatures, steels should contain as little C, P and S as possible and be alloyed with Ni. Inherently fine-grained steels are used, in order to secure a fine austenite grain structure in the finished components. Superior low-temperature properties are difficult to obtain in cast steels, because of the additional structural imperfections in the primary austenite grain boundaries and on the dendrite interfaces. Steel 35GTRL contained 0.30-0.40 percent C, 0.9-1.4 percent Mn, 0.4-0.9 percent Si, 0.001-0.003 percent B, 0.005-0.003 percent Ti, 0.05 percent S and 0.06 percent P. Melting as described ensured a high degree of purity with respect to refractory nitrides and high-silica silicates; the fine non-metallic inclusions, of suitable form and location, occurred as scattered globules inside the primary austenite grains. The low-temperature toughness of the steel from 10 melts was determined in the normalized and quenched martensitic states. The austenitisation temperatures were 890 and 1050 deg C and the soaking period 45 min; the quenched testpieces were tempered for 90 min at 180-200 deg C. It was established that when steel 35 GTRL is quenched from the ordinary low austenitising temperature its threshold lies between 0 and +20 deg C, i.e., it is already brittle at room temperature. Quenching from 1050 deg C lowers the threshold below-60 deg C and makes the steel superior to other cast steels in low-temperature toughness. The threshold temperature for steel 35 GTRL normalized from 890 deg C is also below-60 deg C and thus lower by 20-40 deg C than for other cast steels currently used in mass production. When the normalizing temperature for steel 35 GTRL is raised to 1050 deg C, its brittle threshold temperature once again shifts back to the room-temperature range.

  • Corporate Authors:

    British Cast Iron Research Association

    Alvechurch
    Birmingham,   England 
  • Authors:
    • Yakimova, A I
    • Shvedunov, A I
  • Publication Date: 1974-6

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Filing Info

  • Accession Number: 00128890
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Feb 4 1976 12:00AM