Effects of Shape Size of Specimens on Creep and Rupture Properties of Low Carbon Steel

Abstract

The effects of changes in shape and size of specimens on creep and rupture properties of low carbon steel were investigated on the plate specimens having various thickness (t0), breadth (b0) and parallel length (L0). t0 ranged from 2 to 30mm, b0 from 30 to 60mm, and L0 from 32 to 180mm. L0/√A (A: area of cross section) varied between 2 and 13.7. Creep and rupture tests were carried out at 450°C and 550°C.It is shown that, with increasing L0/√A, the rupture time decreases in the case of plate specimens when L0/√A≤6, but it is constant when L0/√A>6. On the other hand, it increases with L0/√A in the case of round specimens when L0/√A≤6. With increasing L0/√A, the minimum creep rate increases in the case of plate specimens when L0/√A is small, but it is constant when L0/√A>6. The changes in t0, b0 and L0 of the plate specimens affect both the rupture time and the minimum creep rate little if L0/√A is maintained constant.In the case of short rupture time, the plate specimens with the dimensions of b0/t0>10 show the fracture oblique to the tensile axis across the broad sides. The angle of inclination made by the line of fracture is approximately 60°.