Microstructure and Impact Properties of Heat Resistant Steels with Different Aluminum Contents

According to the bulk non-ferrous net reprinted: Ultra-supercritical power generation technology is the main direction of development of China's thermal power units, which is more stringent requirements on the high temperature strength and anti-oxidation corrosion performance of the unit materials. ZG1Cr10NiAlMoVNbN is a newly developed ferrite type heat-resistant steel. Among them, the addition of aluminum can improve the material's resistance to oxidation, high temperature strength, coking resistance and carburization resistance. At the same time, since aluminum is a ferrite forming element, the single-phase region of austenite is reduced and shifted to the right. When the mass fraction is too high, δ-ferrite may remain in the room-temperature structure of the material, but δ-ferrite will reduce the steel. The impact toughness and long-term strength and other properties.

The scholars of Harbin Engineering University used Thermo-Calc thermodynamic software and experimental research methods to simulate the equilibrium phase and non-equilibrium solidification of ZG1Cr10NiAl-MoVNbN heat-resistant steel with different aluminum mass fractions between 200 and 1600°C. In the process, the microstructures of the three test steels were studied and subjected to impact tests. The results show that the equilibrium phase of aluminum test steel with mass fraction of 0.10% is γ single phase at 1050°C; the equilibrium phase of aluminum test steel with mass fraction of 0.91% is γ phase + δ ferrite phase; the mass fraction is 3.67 The equilibrium phase of % aluminum test steel is δ-ferrite single phase, and the simulation results are in good agreement with the test results. At the same time, with the increase of aluminum mass fraction in steel, the impact energy is greatly reduced, and the fracture mode of impact test specimens is improved by the toughness. The foliation becomes a cleavage fracture.