DOI: 10.52150/2522-9117-2020-34-190-201
Razdobreev Valery Guriyovych, PhD (Engin.), Senior Researcher, Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail: v_razdobreev@mail.ru; ORCID 0000-0001-7402-7992
Effect of carbon on the corrosion behavior of thermally hardened rolled products
Summary. In this work, we studied the corrosion behavior of hot-rolled and heat-hardened rolled products made of carbon steel with different carbon content in order to select the optimal conditions for its heat treatment to obtain a satisfactory combination of strength and corrosion resistance during the development of processes of general corrosion with hydrogen depolarization. The studies were carried out on samples of carbon steel (0.14-0.8% C) in hot-rolled and heat-hardened states. It has been established that the corrosion rate (K) in specimens made of steels in the quenched state is lower than in the hot-rolled state; however, even in this state, with an increase in the carbon content within the studied limits, it increases 40 times. An increase in the corrosion rate with an increase in the carbon content in hot-rolled steel is explained by an increase in the amount of pearlite and an increase in the length of the ferite-cementite interphase boundaries. It was determined that in quenched hardened steel in the carbon content range from 0.14 to 0.80 % C, an increase in the corrosion rate is apparently due to an increase in microstresses (accumulation of excess internal energy) associated with an increase in the tetragonality of the martensite lattice and the appearance of concentration inhomogeneity in the solid solution. It was found that during the course of corrosion with hydrogen depolarization, the dependences of the general corrosion rate of thermally hardened structural steels on the tempering temperatures are described by extreme dependences with a maximum corrosivity in the temperature range of 350-500 oC, while, with an increase in the carbon content in steel, rental increases. It was determined that at the tempering temperature corresponding to the maximum K, the corrosion rate is 1,5-3,6 times higher than in the quenched state, and 1,4-2,6 times higher than in hot-rolled, and with an increase in the carbon content this difference is growing. An increase in the rate of corrosion with hydrogen depolarization in the tempering temperature range of 350-450 oC is apparently associated with the process of carbide formation and the appearance of coherent stresses during the release of dispersed particles. An increase in corrosion losses in this interval with an increase in carbon content is due to an increase in the volume fraction of fine particles of the carbide phase and an increase in the level of elastic microdistortions of the crystal lattice (Δa/a).
Keywords: carbon steel, hot rolled and tempered condition, thermal hardening, tempering temperature, corrosion rate
References
Panasyuk V.V., Andreykiv O.YE. & Parton V.Z. (1988). Mekhanika ruynuvannya i mitsnist materialiv: Sprav. posibnyk [Mechanics of destruction and strength of materials: Ref. manual]. Kyiv: Naukova dumka, 1988, Vol. 1, 488. [In Russian].
Vedenkin S.G. (1975). Vliyaniye sostava nizkolegirovannykh stroitelnykh staley na ikh atmosfernuyu korroziyu [Influence of the composition of low-alloy construction steels on their atmospheric corrosion]. Zashchita metallov [Protection of metals], 1975, Vol. II, 3, 275-289. [In Russian].
Konovalov O.F., Ryzhenkov O.A. & Korolov V.P. (2004). Systemnyy pidkhid do monitorynhu koroziyi ta zakhystu metalevykh konstruktsiy [System approach to corrosion monitoring and protection of metal structures]. Fizyko–khimichna mekhanika materialiv [Physicochemical mechanics of materials], 2004, 5, 99-103. [In Ukrainian].
Kugushin A.A., Uzlov I.G. & Kalmykov V.V. et al. (1986). Vysokoprochnaya armaturnaya stal [High-strength reinforcing steel]. Moskva: Metallurgiya, 1986, 272 p. [In Russian].
Odesskiy P.D. (2018). Sovremennyye stali dlya stroitelnykh metallicheskikh konstruktsiy i voprosy ekonomicheskoy effektivnosti [Modern steels for building metal structures and issues of economic efficiency]. Stal [Steel], 2018, 12, 57-61. [In Russian].
Sokol I.Ya., Ulyanin Ye.A. & Feldgandler E.G. et al. (1989). Struktura i korroziya metallov i splavov [Structure and corrosion of metals and alloys]. Moskva: Metallurgiya, 1989, 400 p. [In Russian].
Korroziya: Spravochnik [Corrosion: Handbook]. (1981). L.L. Schreier (Ed.). Moskva: Metallurgiya, 1981, 631. [In Russian].Razdobreev V.G. (2019). Issledovaniye vliyaniya mikrolegirovaniya borom na korrozionnoye povedeniye nizkouglerodistoy konstruktsionnoy stali v razlichnom strukturnom sostoyanii [Research of the influence of boron microallegation on the corrosion behavior of a low-carbon structural steel in various structural condition] // Fundamentalnyye i prikladnyye problemy chernoy metallurgii: Sb. nauchn. trudov ICHM [Fundamental and applied problems of ferrous metallurgy. Collection of scientific articles ISI NANU], Dnepr: «VIZION», 2019, Vol. 33, 140-152. [In Russian].
Kurdyumov G.V. (1965). O povedenii ugleroda v zakalennoy stali [On the behavior of carbon in hardened steel]. Metallovedeniye i termicheskaya obrabotka metallov [Metal Science and Heat Treatment], 1965, 8, 3-8. [In Russian].
Starodubov K.F., Babich V.K., Serdyuk A.G. & Ulinskiy V.I. (1970). Vliyaniye ugleroda na sostoyaniye tonkoy kristallicheskoy struktury pri otpuske zakalennykh uglerodistykh staley [Influence of carbon on the state of a fine crystalline structure during the tempering of hardened carbon steels]. Termicheskoye uprochneniye prokata: nauch. tr. Instituta chernoy metallurgii [Thermal hardening of rolled products: scientific works of Iron and Steel Institute]. Moskva: Metallurgiya, 1970, Issue 36, 114-119. [In Russian].
