EMBRITTLEMENT OF 5. 5%Ni STEELS ON SLOW COOLING FROM THE FINAL TEMPERING.

Kotobu Nagai, Koji Shibata, Masato Murakami, Toshio Fujita

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Abstract

Embrittlement on slow cooling was studied in intercritically heat treated cryogenic nickel steels which contain reverted austenites. The 5. 5% Ni steels with different Mo and Cr contents were QLT treated and reheated at 600 degree C for 20 min and cooled at a rate of about 0. 2 K/min to temperatures at which cooling was interrupted by water quenching. Three types of embrittlement took place depending on chemical compositions and interrupted temperatures. Intergranular failure was a characteristic feature in Mo free and 0. 4 Mo steels. In the case of 0. 2 and 0. 8 Mo steels, no intergranular fracture was observed and quasi-cleavage fracture became more dominant with a decrease in the intermediate quenching temperature. As cooling proceeded the yield strength decreased or remained at a low level at first, increased gradually and reached a constant level. For 0. 6Cr-0. 4 and 0. 8Mo steels, martensitic transformation of the unstable austenite appeared at a low tensile stress level and decreased both yield strength and toughness.

Original languageEnglish
Pages (from-to)462-469
Number of pages8
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume69
Issue number3
Publication statusPublished - 1983 Mar
Externally publishedYes

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ASJC Scopus subject areas

  • Metals and Alloys

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