抄録
The effect of nitrogen content on tensile properties of SUS304L with N content less than 0.21% and SUS316L less than 0.23% have been investigated at cryogenic temperatures and the following conclusions were obtained.
(1) Complicated temperature dependence of 0.2% proof stress appeared in the range of lower N content in the temperature range from 220K to 77K. This phenomenon is probably caused by the stress induced ε matensitic transformation.
(2) The increase of 0.2% proof stress with N content at 4K was larger than that with C content.
(3) Work hardening was prominent in steels with lower N content and at lower temperatures. This is attributed to instability of austenite.
(4) An elongation peak appeared slightly below the upper limit temperature of stress induced α' martensitic transformation.
