The Study On Effect Of Bending Deformation On Mechanical Properties Of Sheet Metal

In the course of UOE welding pipe manufacturing, the sheet metal accepts bending deformation. The pipe outer surface receives tensile deformation, due to work hardening effect, it makes yield strength of the pipe outer surface in the circumferential direction increasing. The pipe inner surface receives compression deformation, due to the the impact of Bauschinger effect, it makes yield strength of the pipe inner surface in the circumferential direction decreasing. This makes some differences between the roughcast sheet metal and tube about yield strength. So the people who engaged in UOE forming process design will encounter such a problem as follow, when designing UOE forming process of steel pipe, how to reserve the yield strength of roughcast sheet metal. With the rapid development of large-diameter line pipe manufacturing, it will become a hot issue in the field of the discipline in the future.Based on the characteristic of bending deformation in UOE forming, this paper uses four points bending and makes use of large-scale nonlinear finite element software called MSC.MARC in order to set up 2D element simulation model of bending process. Through many numerical simulations, the allowing pre-deformation after bending achieves the requirements of UOE forming products ,then we identify the parameters of parameters and analyze the factors which influence the pre-deformation and the length of the uniformity in the process of the bending, such as the radius of the punch, the distance of the punch and the die, the thickness of the sheet metal and so on.According to API Spel 5L standard, the yield strength of the sampling tube flattened specimen indicated that the yield strength of the tube from oil(gas) line pipe. At first, we get different radius of the sheet metal by bending and flatting experiments and calculate the pre-deformation which is in the range of deformation of UOE forming products in this paper. Then, we flat the roughcast and sheet metal after the bending in order to prepare the single-direction tension experimental study.We make rectangle specimens from the roughcast sheet metal and the sheet metal after bending and flatting in order to make the tests of yield mechanical properties and analyze the variable rule of mechanical parameters such as yield strength, tensile strength, y-t strength ratio, elongation, work-hardening index and so on. At last, we get out the approximate quantitative relationship of the mechanical properties between the roughcast sheet metal and the tube.