The influence of long-term aging on microstructures and static mechanical properties of P92 steel at room temperature

The heat-resistant steel P92 aged at 650°C for up to 200h, 500h, 1000h, 2000h, 3000h, 5000h, has been investigated on the static mechanical properties and microstructural evolution using post-aged tensile tests, OM observations, SEM examinations and TEM investigations. Variation of the static mechanical property parameters, including yield strength (σ_ys), ultimate tensile strength (σ_ult), the modulus of elasticity (E), elongation (δ) and reduction of area (φ_f), were exhibited systematically and the microstructures of the aged specimens were also discussed to reveal the possible reason for the deteriorations during aging. Experimental results indicate that martensitic lath structure gradually recovers during long-term aging, and the precipitation of spheroidal M₂₃C₆ grows continuously with increasing aging time, but MX seems to be stable. Moreover, Laves phase nucleates and grows rapidly during aging, which plays a key role in the variation of the static mechanical properties in this study.