INFLUENCE OF THE AMOUNT OF AUSTENITE ON THE TOUGHNESS OF TWO PHASE STAINLESS STEELS.

In heating at 700 degree C, the ferritic alloy was embrittled by carbide precipitation. In the alloys containing more than 20% gamma , there was no embrittlement. Marked embrittlement is observed after prolonged heating by formation of sigma phase. The embrittlement by sigma phase produced by decomposition of ferrite could not be reduced by coexisting gamma . On aging at 500 degree C of water-quenched specimens, the maximum increases in hardness and Charpy impact transition temperature appeared at 20% gamma , where the maximum residual stress of ferrite was observed.