Effects of Heating Temperature on Microstructures and Properties of X80 Grade Hot-bending Bends

The effects of heating temperature on microstructures and properties of X80 grade heating bending were studied through thermal simulation, mechanical property test and microscopic analysis. The results showed that the strength of X80grade hot-bending bends increases while plasticity and toughness decrease with the heating temperature increasing. When the heating temperature is 950 ℃, the microstructures of the experimental steel mainly consist of granular bainite and bainitic ferrite, including some soft-plastic mixture microstructure, and a better combination of strength and toughness can be obtained due to the fine effective grains and the mixed multiphase microstructure. The coarse BF laths traversing the austenite grain boundary can lead to a severe deterioration of the toughness when heating temperature is above 1 050 ℃. The PF is not in favor of the strength improvement when heated at 850 ℃ in the two-phase region.