| Abstrakt: |
1.Aging of steel N18K9M5T under stress in the macroelastic region (s > (0.3–0.4)s0.2) substantially improves the values of s0.02, s0.2, and sb, especially s0.02 (?s0.02=30–40 kgf/mm2), and also the resistance to crack propagation. The increase in the values of the mechanical properties with aging under stress depends on the original condition of martensite (freshly hardened, partially aged), the applied stress (the higher the stress, the greater the improvement), the temperature, and the aging time. The optimal temperature is 500°.2.The anamalously low value of the fracture toughness of steel N18K9M5T after aging at low temperatures is doubled by aging under stress.3.The improvement in the mechanical properties is due to the effect of applied stress on the aging of martensite — decomposition of martensite is accelerated and also relaxation or microstresses.4.Aging under stress can be recommended as a promising method for improving the mechanical properties of high-strength maraging steels. |
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