In order to achieve better strength and toughness matching for the newly developed Fe-C-Cr-Ni-Mo-Co-Al co-precipitation hardening ultra-high strength steel,this study deeply discussed the mechanism of dual-aging process on the microstructure evolution and mechanical properties of experimental steel,and determined the optimal aging pro-cess parameters to achieve excellent strength and toughness.The results show that the experimental steel could achieve higher ultimate tensile strength(1 924 MPa)under normal aging treatment,but lower yield strength and toughness.The dual-aging technology(570℃×0.5 h+480℃×20 h)could achieve superior combination of strength and toughness.After the optimal dual-aging treatment,the yield strength has been increased by 224 MPa and the im-pact work has been increased by 77% while the ultimate tensile strength was merely decreased by 42 MPa,with an er-ror range of±0.5 J for the impact toughness.The microstructure characterization and theoretical calculation results show that the content of precipitation-hardening phases and reversed austenite play decisive role in the strength and toughness of the experimental steel.The higher pre-aging temperature is benefit to the nucleation and growth of the re-versed austenite and the secondary hardening precipitates in the experimental steel.The formation of reversed austen-ite is helpful to increase the impact energy of the test steel,but high austenite content would significantly reduce the strength of the steel.When continuously aged at 610℃,precipitates coarsening and martensite microstructure recov-ery would lead to a decrease in strength and toughness.
关键词
复合析出强化型超高强度钢/双时效工艺/强韧性/动力学计算
Key words
Co-precipitation Hardening Ultra-high Strength Steel/Dual-aging Process/Strength and Toughness/Dynamic Calculation
维普
万方数据