STUDY OF THE EFFECT OF TEMPERING ON K-IEAC OF A NI-CR-MO STEEL USING UNPRECRACKED CHARPY TYPE SPECIMENS

The threshold stress intensity factor for environment assisted crackin g, K-IEAC, has been investigated on a Ni-Cr-Mo structural steel in 3.5 % sodium chloride solution with the help of a new test principle using unprecracked Charpy type specimens. The estimated values of K-IEAC fo r different tempered conditions of the steel and the trend of variatio n of these values with tempering temperature are shown to be in good a greement with similar reported results. Using results of hardness test , dilatometric measurements and scanning electron microscopic examinat ion, it is demonstrated that K-IEAC is susceptible to tempered martens ite embrittlement.