EFFECT OF SOLUTION TREATMENT ON THE TRANSFORMATION BEHAVIOR OF COLD-ROLLED DUPLEX STAINLESS-STEELS

The transformation kinetics of the gamma --> alpha transition in duple x stainless steels (Feroplug materials) within the solution treatment temperature range of 1050-1250 degrees C and the accompanying ageing b ehaviour have been studied by the use of optical/scanning electron mic roscopy, an image analyzer and magnetic measurements. Increasing the s olution treatment temperature increases the amount of ferrite and redu ces the anisotropy in the morphology of the ferrite phase in the matri x. In addition, an increase in the ferrite content leads to less chrom ium and more nickel within the ferrite phase. Ageing at 600 degrees C and 700 degrees C showed that the starling time of ferrite transformat ion (decomposition) is independent of the solution treatment temperatu re. The main influence of solution treatment temperature is on the ove rall time required for completion of transformation and the morphology of the secondary austenite (gamma(2)) formed during transformation. a higher solution treatment temperature produces a ferrite phase of low er chromium content, this increases the time required for the alpha -- > gamma(2) + sigma transformation and produces needle-shaped intragran ular gamma(2)