PROPOSED MODIFICATION TO SCHAEFFLER DIAGRAM FOR CHROME EQUIVALENTS AND CARBON FOR MORE ACCURATE PREDICTION OF MARTENSITE CONTENT

The austenitizing effect of carbon strongly alters the microstructure of Cr-Ni steels, which is not taken into consideration by the Ni equiv alent in the Schaeffler diagram. By determining the austenitizing effe ct of carbon and the alloying elements, a mathematical formula was dev ised to calculate a new nickel equivalent, denoted as Ni-eqB. On the b asis of this, the Schaeffler diagram can be improved. A new regression equation was constructed that gives a good estimation of the measured M-s temperatures. It was concluded that M-s temperatures for the hard enable high-alloy creep-resistant steels, depending on the composition of the steel heats, vary over a wide range. That is why the crack sen sitivity of weld metal changes strongly during the welding operation.