The Evolution of a Microstructure during Tempering and Its Influence on the Mechanical Properties of AerMet 100 Steel

In order to provide guidance for furthering the balance of strength and toughness of AerMet 100 steel through tempering treatment, the effects of the tempering time on microstructure and mechanical properties are investigated. The microstructure evolution, especially M2C precipitates and austenite in AerMet 100 tempered at 482 degrees C for 1 similar to 20 h, was characterized, and its influences on the mechanical properties were studied. The tensile strength decreases gradually, the yield strength increases first and then decreases, and the fracture toughness K-IC increases gradually with an increasing tempering time. The strength and toughness matching of AerMet 100 steel is achieved by tempering at 482 degrees C for 5 similar to 7 h. Without considering the martensitic size effect, the influence of the dislocation density on the tensile strength is more significant during tempering at 482 degrees C. The precipitation strengthening mechanism plays a dominant role in the yield strength when tempering for 5 h or less, and the combined influence of carbide coarsening and a sharp decrease in the dislocation density resulted in a significant decrease in tensile strength when tempering for 8 h or more. The fracture toughness K-IC is primarily influenced by the reverted austenite, so that K-IC increases gradually with the prolongation of the tempering time. However, a significant decrease in the dislocation density resulting from long-term tempering has a certain impact on K-IC, giving rise to a decrease in the rising amplitude in K-IC after tempering for 8 h or more.

Automated summary

The effects of tempering time on the microstructure and mechanical properties of AerMet 100 steel were investigated. It was found that a tempering time of 5 to 7 hours at 482 degrees C achieved the desired balance of strength and toughness. Tempering time influenced the tensile strength, yield strength, and fracture toughness of the steel.