Characterizing and Modeling Transformation-Induced Plasticity in 13Cr-4Ni Welds upon Cooling

Dilatometric experiments were conducted with the main purpose of measuring the transformation-induced coefficients of 13% chromium and 4% nickel, which are martensitic stainless steel base and filler materials used for hydraulic turbine manufacturing. To this end, a set of experiments was conducted in a quenching dilatometer equipped with loading capabilities. The measurement system was further improved by means of modified pushrods to allow for the use of specimens with geometries that are compliant with tensile test standards. This improvement allowed for the measurement of the materials' phases and respective yield strengths. The dataset was further used to determine the relationship between the applied external stress and the martensitic start temperature (Ms) upon cooling. The TRIP coefficient's K values for both the S41500 steel and E410NiMo filler material were measured at 8.12×10-5 and 7.11×10-5, respectively. Additionally, the solid phase transformation model parameters for both the austenitic and martensitic transformation of the filler material were measured. These parameters were then used to model austenitic-phase-transformation kinetics and martensite transformation, including transformation-induced plasticity effects. Good agreement was achieved between the calculation and the experiments.