Effect of reverse austenite transformation on the microstructure and properties of 3J33B alloy

This study investigates the changes in microstructure, mechanical properties, and frequency-temperature coefficients of 3J33B high-elasticity alloy under different aging heat treatment conditions. As a significant material in aerospace and precision instruments, the 3J33B alloy exhibits an ultra-low carbon martensitic structure in its solution-treated state, which can reversibly transform into austenite after aging treatment, significantly affecting its physical and mechanical properties. By systematically adjusting the aging temperature and duration, the study found that aging treatment not only promotes the precipitation of nanoscale γ′ strengthening phase, enhancing the alloy's strength, but also regulates the alloy′s toughness and frequency-temperature coefficient through the formation and growth of reversed austenite. The tensile strength of the alloy reaches its peak of 2 173 MPa at 500 ℃ aging, while the frequency-temperature coefficient is minimized at 625 to 650 ℃ aging, approximately (10-20)×10^-6/℃. These findings provide a theoretical basis and optimization direction for the application of 3J33B alloy in high-precision navigation systems.