SU704995A1 - Method of thermal processing of stainless martensite aging steels - Google Patents

Description

(54) THE METHOD OF THERMAL TREATMENT. THE STEELS OF 1B1C1 OF THE MARTEN-LESSING STEELS were aging at a decrease from temperature to 7 hours. Tests of samples with a transverse direction of the fiber gave the correct results; . 161.5 kg / mm 149.0 kg / mm 8% N, 32.0% dts poper. 3.2 kgm / cm. The heat treatment according to the indicated regime provided high strength with satisfactory plasticity and viscosity. Example 2. The workpiece was subjected to processing twice; heated at a rate of 15 ° / min to a temperature of 980 ° C, kept for 2 hours and cooled in oil. The third time was heated with the same scurry to a temperature of 800 ° C, which exceeded the temperature of the end of the polymorphic transformation at 100 ° C, held for 2 hours and cooled in oil. After that, the blanks were cold-treated at -70 ° C for bh and subjected to aging at temperatures ranging from up to 400 ° C for 7 hours. Tests of samples with a transverse direction of the fiber gave the following results: bv. 13.5..R kg / mm (about, 143.0 kgUm d, 6.5% U 25,, 0% of the accumulator, 2.5 kgm / cm "Comparison with the results of the application of 1 reveals a decrease in temperature final quenching from 920 to 800 ° C. Example 3. The blanks were heated at a rate of up to a temperature of 980 ° C, held for 2 hours and cooled in oil.This cycle was repeated three times, i.e. the final quenching temperature was also equal to 980С, which corresponds to Asz temperature + 280 ° C. After quenching, the billet was chilled at a temperature of -70 ° C for 6 hours and then subjected to aging at lower temperatures from 530 ° C to 40 ° C: temperatures during 7 hours Sample testing with a transverse direction of the fiber and the following results: (151.0 kg / mm god, 140.5 kg / mm if, 8.5% H 35.0% 01c pop., 3.7 kgm / cm A comparison of the results of the tests in examples 1, 2, 3 shows that in the case of a final zakag.khi with a temperature of 980s, the ductility and viscosity are only slightly higher than after quenching from 920 ° С, but the strength is lower than. lower values of both strength and viscosity are obtained. Thus, testing three heating temperatures for final quenching, corresponding to temperatures exceeding the temperature of the end of polymorphic transformation by 100, 220, and 280 ° C, showed the advantage of final quenching from temperature Ac a + 220 C. Example 4. The blanks were heated at a rate of 15 ° / min to a temperature of 980 ° C, kept for 2 hours and cooled in oil. This cycle was conducted twice. The third time was heated at the same speed to a temperature of 920 ° C, kept for 2 hours. and cooled in oil. After that, the blanks were cold-treated at -40 ° C for 6 hours and subjected to aging at temperatures falling from 530 ° C to 400 ° C for 7 hours. Tests of samples with a transverse direction of the fiber gave the following results: GB, 154.0 kg / mm (5-2, 145.0 kg / mm cf, 8.2% 436.5% Oj, backwards, 3.5 kgm / cm with the previous example, it shows that the temperature during cold processing (-40 ° C) is not low enough to measure strength. The third time was heated at the same speed to a temperature of 920 s, kept for 2 hours and cooled in oil. After this, the blanks processed in cold at a temperature of 6 hours and subjected to aging at a temperature of 530 ° C for 7 hours. Results, tests that follow. & b, 149.0 kg / mm boa 137.0 kg / mm, cJ, 7.5%, H, ab, 5% with Gnpop., 3.4 kgm / cm. The above examples justify the optimality of the selected parameters of the heat treatment mode. The results obtained after heat treatment of the proposed and known methods are shown in the table. y and a l and c

1. Heating up to 980 ° С at a rate of 15 ° / min, holding for 2 hours, cooling in oil.

The cycle is repeated three times.

2. Aging, 7 o'clock

3.5

34.5

8.0

Heat Treatment Mode

The proposed method

1. Heating up at a speed of 15 / min, shutter speed 2 hours, cooling in oil.

The cycle is repeated twice.

2. Heating up to 920 C at IS / MHH speed, 2 hour aging, oil cooling

3. Cold treatment

at -TO ° C for 6 hours

4. Aging at lower temperatures from to

7 o'clock Distinctive features of the proposed method, namely, a decrease in the temperature of the final quenching, cold treatment at a temperature of (-60 (-80) ° C, aging at lower temperatures from 550-530 ° C to 400 ° C. Temperatures, increase the strength by 15 Kr / K "Vi without lowering below the required plasticity and viscosity standards, which ultimately significantly increase the structural strength. Reducing the final quenching temperature allows obtaining a more dispersed martensite structure, which provides a certain improvement in strength. However The final quenching temperature should significantly exceed the temperature of the end of the polymorphic transformation, since forming with austenite at temperatures higher than Asl even by can retain significant heterogeneity in composition, which subsequently leads to significant amounts of stable residual austenite that reduces strength. Indeed, as you can see from examples 1, 2, after final hardening, strength and viscosity are lower than after hardening from 920С. Cold treatment destabilizes residual austenite and contributes to its transformation into martensite, which also increases strength. Stripping at lower temperatures increases strength by realizing the release of hardening particles of various types. The use of the proposed method of heat treatment of products from

. With p -kg / Mvfj f, ° / o y,% U.

161 ,, 5

149.0

8.0

Claims (1)

32,03,2 stainless martensiton 1S1 their steels Provides high strength. level 160 kg / mm (see table), while the existing method allows to obtain strength only at the level of 143 kg / mm. However, the proposed method, alike. as well-known, it provides sufficiently high ductility and viscosity in the direction across the fiber, respectively T-34.5% and H-32% and OH-3.5 kgm / cm and OH- 3.2 kgm / cm, rather high impact viscosity and ductility are created by cyclic quenching after heating at a rate of 10-30 ° / min. An increase in strength after treatment is provided by lowering the final quenching temperature, cold working and aging at lower temperatures. High strength in combination with availability of plasticity and strength provides a significant increase in the structural strength of products, which, in turn, will increase their reliability. The method of the invention The method of heat treatment of stainless martensite steels, including multiple quenching after heating at a rate of 10-ZO / min from Acj to 980-lOOO C n, holding and aging, characterized in that, in order to increase strength at a given level of ductility and viscosity, the last quenching is carried out at the Lez + temperature (200-220 s), and after it the treatment 7704995 -,  . to, “and and with. heh „, -„; .., 2 bi T2Go; Go 19bG  - - ,, ss.