Effect of aging regime on amount of residual austenite in fuel equipment parts
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The existing methods of quenching fix the residual austenite in the structure of ShKh15 and KhVG steels.
The aging of tempered specimens at 130–140° for 24–48 hours does not cause any further reduction in the residual austenite and should not be recommended.
The aging of parts made of ShKh15 and KhVG steels at 160° reduces the amount of residual austenite by 1.5–2.5%, the most intensive decomposition occurring in the case of KhVG steel within the first 2 to 4 hours, and in the case of ShKh15 steel within the first 5–7 hours. Further soaking is technologically inadvisable.
Tempering at temperatures not above 160° as well as prolonged aging at 130–140° do not harden the residual austenite. Stable dimensions of parts made of ShKh15 and KhVG steels are only obtained after cold working (−30–70°) if the latter is applied immediately after quenching.
We can recommend the following heat treatment regime for parts made of ShKh15 or KhVG steels for fuel equipment:
quenching from 830–840° in alkali or oil;
cold working at −30–−70°;
tempering at 160° for 4 or 5 hours, cooling in air;
aging after machining for 2 or 3 hours at 160°.
KeywordsHeat Treatment Austenite Treatment Regime Cold Working Stable Dimension
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