The Influence of Bending Tube Forming Process on the Microstructure and Properties of L360Q Steel

This article adopts the hot bending test method to systematically analyze the hardness, tensile properties, and Charpy impact strength of different parts of L360Q seamless steel pipes through local induction heating bending and tempering heat treatment. The metallographic structure is observed, and the mechanical properties of L360Q steel before and after hot bending and heat treatment are compared and analyzed. The experimental results indicate that due to uneven temperature distribution during the heating process, there are differences in the deformation of various parts of the bent pipe, which in turn leads to differences in microstructure and properties. The tensile strength of the transition zone of the bent pipe at the beginning of the arc is 588 MPa, and the yield strength is 520 MPa, which is significantly higher than the original base material (straight seamless steel pipe) and other parts of the bent pipe; In the vicinity of the starting and ending arc sections, the hardness value is higher than that of other parts of the pipe body; After undergoing hot bending and tempering heat treatment, the metal elongation of the original base material will decrease, but the overall change in toughness is not significant, indicating that the effect of hot bending and tempering heat treatment on the toughness of steel pipes is limited. The hot bending and heat treatment process of this study meets the requirements of GBT 9711-2017 and SY5257-2012 standards, providing technical reserves and references for the design of L360Q pipeline bends.