Atmosphere protection heat treatment technology of ultrahigh strength D6AC steel thin-wall tube

Abstract

The invention discloses an atmosphere protection heat treatment technology of an ultrahigh strength D6AC steel thin-wall tube. The atmosphere protection heat treatment technology is characterized by comprising the steps of atmosphere protection quenching, secondary nitrogen protection tempering, and vacuum heat aging after semi-finishing. Compared with the prior art, the solution strengthening effect, the phase change strengthening effect and the dispersion strengthening of ultrahigh strength steel can be improved, the internal stress is reduced, and oxygenation and decarbonization are eliminated, so that the tensile strength, the yield strength, the percentage elongation after fracture, the percentage reduction of area, and the size stability and precision after finishing of the thin-wall tube are improved, and a machining allowance before heat treatment is reduced.

Description

technical field [0001] The invention belongs to the technical field of metal heat treatment, and in particular relates to an atmosphere protection heat treatment process for ultra-high-strength D6AC steel thin-walled pipe fittings. Background technique [0002] Atmosphere protection heat treatment has the advantages of no oxidation and decarburization, high strength, good toughness and plasticity, small internal stress, good dimensional stability and high precision after machining, and is a metal thermal processing method pursued by the heat treatment industry for a long time. Atmosphere protection heat treatment has been widely used in the heat treatment of tempered steel precision parts, but it is rarely used in the heat treatment of ultra-high strength D6AC steel. [0003] At present, domestic heat treatment of ultra-high-strength D6AC steel, especially thin-walled pipe fittings made of ultra-high-strength D6AC steel, mainly relies on quenching and tempering heat treatmen...

AI Technical Summary

Problems solved by technology

[0003] At present, domestic heat treatment of ultra-high-strength D6AC steel, especially thin-walled pipe fittings made of ultra-high-strength D6AC steel, mainly relies on quenching and tempering heat treatment process. , box furnace tempering heating, heat preservation, tap water tempering cooling, this process has thick oxide skin, large machining allowance, low strength, low toughness and plasticity, large internal stress, large deformation after subsequent machining, and poor dimensional stability; The tensile strength obtained by the process is within 1530Mpa, the yield strength is within 1420Mpa, the elongation after fracture is within 9%, and the reduction of area is within 35%.

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