Identification of Transformation Plasticity Coefficient by Four-Point Bending Tests and Some Data under Pearlite Transformation
Takayuki OTSUKA and Tatsuo INOUE
Abstract:Four-point bending tests are employed to identify the coefficient of transformation plasticity, which plays an important role in the inelastic constitutive equation applied to more sophisticated heat treatment process simulation. In this paper, a slender bar type specimen is chosen for the bending tests to identify the transformation plasticity coefficient during pearlite reaction, which is also possible for martensite transformation under high cooling rate when using a pipe specimen. An austenized steel bar is cooled down in the air by free convection under four bending load. When the temperature reaches the pearlite start point, so remarkable deflection progress due to the effect of transformation plasticity until pearlite finish temperature. The TP strain is easily evaluated from the data of the deflection as a function of applied deviatric stress, which gives the value of the coefficient. Some data under different applied stress by choosing the diameter of the bar with 5 or 3mm and taken by other method in references. The obtained data of coefficient of transformation plasticity will be piled up in the materials database MATEQ (MATerial database for Quenching process simulation) now released by the Society of Material Science, Japan (JSMS) available for heat treatment simulation. Key Words:Four-point bending, Transformation plasticity, Pearlitic transformation, MATEQ, Constitutive equation