MICROSTRUCTURE AND PROPERTIES OF NITROCEMENTED LAYER OF CAST NEEDLE SPROCKETS MADE OF CARBON STEEL

Admin bo'lib kirish (www.admin.slib.uz)

Tizim sinov (TEST) rejimida ishlamoqda! Murojat uchun @slib_support

Eski talqinga o'tish link

23 июл 2021

Asosiy til:Ingliz

MICROSTRUCTURE AND PROPERTIES OF NITROCEMENTED LAYER OF CAST NEEDLE SPROCKETS MADE OF CARBON STEEL

Fan yo'nalishi:

60fa61261d0c8.pdf

PDF

Technical science and innovation

Maqola chop etish see more

MAQOLA ANNOTATSIYASI

This article presents the results of scientific and experimental investigations of cast rotary needle sprockets of earth-moving machines made of carbon steel. Chemical composition, mechanical properties and macro- and microstructure parameters of the same steels are studied. The surface layer of steel was calculated after chemical-thermal preparation - nitrocementation with a coating thickness of between 0.6 and 1 mm. On an MBS-9 metallographic macroscope, the layer thickness was measured at various magnifications. The optimal nitrocementation modes have been implemented with concurrent hardening and low tempering. The surface layer macrostructures of specially prepared samples with different carbon concentrations, consisting of a fine-grained structure, are given. The structure of the nitro-cemented layer should consist of fine crystalline martensite, small quantities of fine evenly scattered carbonitrides, and a smaller quantity of residual austenite under optimal saturation conditions. In all carbonaceous steels investigated with equivalent carbon and nitrogen content, the simple residual austenite content in the surface layer is found to be the same. Subsequent increases in nitrogen concentration in the layer lead to an increase in residual austenite content and a decrease in the hardness of the surface coating of samples and machine parts. With higher carbon and nitrogen concentrations, the structure of the steel sublayer also changes. The surface layer hardness of the samples after quenching and low tempering is also analyzed at 56-58 HRC, and the microhardness is 570-690 HB. The surface of the samples consists of a 0.6-0.8 mm thick coating, and further along the depth of the layer the structure of martensite. With the same structure of the surface zone of carbonaceous steels due to a sharp decrease in carbon concentration along the depth of the layer, the structure of martensite with austenite at a shallower depth transitions to martensitic-troostitic and then to troostitic-sorbitic structure of steel. All reference grain sizes are characterized by scores. Fine-grained steels have high hardness and wear resistance of steel parts. Further the process occurs at a lower temperature of 840-8600 C instead of 920-9500 C; layer thickness is less; less deformation and warping of parts is obtained; hardness and resistance to wear and corrosion are increased. It is established that the hardness and wear resistance of the sprocket after optimal heat treatment increases by 2-3 times.

MUALIFLAR

Teglar

# microstructure# hardness# composition and properties of st# chemical and thermal processing # optimum hardening and low temper

Maqolani baholang

0

0 ta

Maqola idintifikatorlari

ROI:

https://eroi.uz/11.0008/A0721-0046

DOI:

Mavjud emas

Foydalanilgan adabiyotlar

1. Lakhtin Y.M. Material Science. - Moscow: Mechanical Engineering, 2014. p - 527 (in Russian ).

2. Shmykov, A.A. Thermist's Handbook - Moscow: Mechanical engineering, 2005. p - 392 (in Russian).

3. Geller, Y.A. Material Science. - Moscow: Metallurgy, 1994. p - 381 (in Russian).

4. Tilabov B.N., Sherbatayev Zh.A., Normurodov U.E., Isaev S.I. Antiwear hard-alloy coatings for parts of agricultural machines and mechanisms // Technical sciences scientific journal UNIVERSUM: Part 1. - Moscow 2020. - P. 32-38.

5. Mukhamedov, A.A.; Berdiev, D.M. Increase of wear resistance of the soil cultivating machine parts by heat treatment // Composite materials. Fan wa tarakkiyot. - Tashkent, 2006. №2. Pages - 23-25 (in Russian).

6. Tilabov, B.K.; Muhamedov, A.A. About the deep surface coating of the steel parts at casting on the gasify models // Uzbek NTiP journal "Composite materials". Fan va tarakkiyot - Tashkent, 2014. №3. Pages - 70-73 (in Russian).

7. Normurodov U.E., Tilabov B.K. Nitrocementation at 840°c with subsequent hardening of the surface layer of cast rotary sprockets of earth working machines // Technical science and innovation. – Toshkent, 2020. №3(05). - pp 216-221.

8. Gulyaev, A.P. Metal science - Moscow: Alliance, 2012 p - 543 (in Russian).

9. Mosberg, R.K. Material Science - Moscow: Higher School, 1994 p - 447 (in Russian).

10. Tilabov, B.K. Development of technology of manufacturing of the loosening tines of the cultivators of the soil tillage machines with a hard alloy coating and thermal strengthening // Proceedings of the V International scientific conference. Technical sciences in Russia and abroad. - Moscow: Buki-Vedi, 2016 Pages - 33-36 (in Russian).

11. Normurodov U.E., Tilabov B.K. Hardness and microhardness of hard-alloy coatings before and after heat treatment // Scientific-technical and production journal Gorny Vestnik. –Uzbekistan January-March 2020. №80. - pp 49-52.

12. Tilabov, B.K. Methods for manufacturing foam models and producing cast harrow teeth with carbide sormatite coating by casting on gasify models and their subsequent heat treatment with double-phase recrystallisation. Universum technical sciences scientific journal. Issue. 10(67). - Moscow, October 2019 Pages - 12-17 (in Russian).

13. Tilabov, B.K. Increased durability of iron parts by thermal treatment with double phase recrystallization. European applied sciences // Europaische Fachhochschule. ORT Publishing. – Germaniy, 2015. #8. - P.49-53.

14. Tilabov B.K. Increase the service life of cast parts tillihg machines // International Conference «Global Science and Innovation» March 23-24, 2016. – USA. Chicago, 2016. - P.222-225.

15. Tilabov B.K., Normurodov U.E. Theoretical basis of steel saturation with carbon and nitrogen and their following thermal treatment // ACADEMEMICIA An International Multidsciplinari Research Journal. – India, Vol.10.oktaber 2020. – pp 491-497.

16. Nоrmurоdоv U.E., Tilаbоv B.Q., Ergashev M., Sadullayev Z.Sh., Sherbo’taev J.A., Choice of material and thermal hardening of surface layers of casting steel parts of soil processing machines and mechanisms // Solid State Technology. – USA, Volume: 63. dekaber 2020. – pp 18631-18639.