Properties of heat-resistant steels after vacuum heat treatment

Conclusions

• 1. Heating in vacuum (10⁻² and 10⁻³ mm Hg) does not change the microrelief on the surface and produces the required surface finish of Δ7.

• 2. Heating and cooling in vacuum (10⁻² and 10⁻³ mm Hg) in treatments 3, 4, 5, 6, 9, 13, and 17 produce a bright surface.

• 3. After heating for quenching the depth of the surface layer depleted of alloying elements was ≤50–60 μ (determined from the microhardness, metallographic analysis, and microanalysis).

• 4. Heating at a pressure of 1·10⁻³ mm Hg for tempering and aging does not cause additional changes in the condition of the surface or the formation of a depleted surface layer.

• 5. The change in the average chemical composition by layers (C, Cr, Mo, W, Ti, Al), determined by sectioning and chemical analysis, does not exceed the limits established by GOST 5632-61 for steels 2Kh13 and 1Kh11MF or for ÉI893 (ChMTU/TsNIIChM 138-66).

• 6. Cooling in inert gases (argon A, GOST 10157-62; nitrogen, GOST 9293-69) at pressures of 400 and 700 mm Hg does not change the chemical composition as compared with cooling in vacuum.

• 7. The mechanical properties of samples heat treated in vacuum (quenching and tempering) indicate that the vacuum treatment, ensuring degassing of the steels, increases the ductility and does not lower the strength.