The influence mechanism of ferrite grain size on strength stress at the fatigue of low-carbon steel
Keywords:ferrite, grain size, fatigue strength, solid solution, carbon
Purpose. Explanation of the influence mechanism of ferrite grain size on the fatigue strength of low-carbon steel. Methodology. Material for research is the low-carbon steel with 0.1% of carbon contnent. The different size of ferrite grain was obtained due to varying the degree of cold plastic deformation and temperature of annealing. The estimation of grain size was conducted using methodologies of quantitative metallography. The microstructure of metal was investigated under a light microscope with increase up to 1500 times. As a fatigue response the fatigue strength of metal – a maximal value of load amplitude with endless endurance limit of specimen was used. Fatigue tests were carried out using the test machine «Saturn-10», at the symmetric cycle of alternating bend loading. Findings. On the basis of research the dependence for fatigue strength of low-carbon steel, which is based on an additive contribution from hardening of solid solution by the atoms of carbon, boundary of the ferrite grain and amount of mobile dislocations was obtained. It was established that as the grainy structure of low-carbon steel enlarges, the influence of grain size on the fatigue strength level is reduced. For the sizes of grains more than 100 mcm, basic influence on fatigue strength begins to pass to the solid solution hardening, which is determined by the state of solid solution of introduction. Originality. From the analysis of the obtained dependences it ensues that with the increase of ferrite grain size the required amount of mobile dislocations for maintenance of conditions for spreading plastic deformation becomes less dependent from the scheme of metal loading. Practical value. The obtained results present certain practical interest when developing of recommendations, directed on the increase of resource of products work from low-carbon steels in the conditions of cyclic loading. Estimation of separate contribution of the studied processes of structural changes with fatigue load allows one to choose a rational solution – to use the hardening effect from the ferrite alloying or to change the grain size of ferrite.
Babich V.K., Gul Yu.P., Dolzhenkov I.Ye. Deformatsionnoye stareniye stali [Strain aging of the steel]. Moscow, Metallurgiya Publ., 1972. 320 p.
Vakulenko I.A., Bolshakov V.I. Morfologiya struktury i deformatsionnoye uprochneniye stali [Structure morphology and strain hardening steel]. Dnipropetrovsk, Makovetskiy Publ., 2008. 196 p.
Vakulenko I.A. Struktura i svoystva uglerodistoy stali pri znakoperemennom deformirovanii [Structure and properties of the carbon steel during the alternating deformation]. Dnipropetrovsk, Gaudeamus Publ., 2003. 94 p.
Vakulenko I.O. Strukturnyi analiz v materialoznavstvi [Structural analysis in the material science]. Dnipropetrovsk, Makovetskyi Publ., 2010. 124 p.
Vakulenko I.A., Pirogov V.A., Babich V.K. O svyazi velichiny krivoy deformatsii s parametrami uravneniya Kholla – Petcha [On the relationship between the value of the deformation curve with the parameters of the Hall – Petch equation]. Metallofizika – Metallophysics, 1986, vol. 8, no. 6, pp. 61-64.
Vakulenko I.O. Pro vzaiemozviazok strukturnykh peretvoren pry vtomi vuhletsevoi stali z osoblyvostiamy budovy poverkhon ruinuvannia [On the relationship of structural changes at fatigue of carbon steel with structural features of the fracture surfaces]. Visnyk Dnipropetrovskoho natsionalnoho universytetu zaliznychnoho transportu [Bulletin of Dnipropetrovsk National University of Railway Transport], 2010, issue 32, pp. 242-245.
Vakulenko I.O. Analiz diahram tsyklichnoho navantazhennia metalevykh materialiv [Analysis of diagrams of cyclic loading for metallic materials]. Visnyk Dnipropetrovskoho natsionalnoho universytetu zaliznychnoho transportu [Bulletin of Dnipropetrovsk National University of Railway Transport], 2009, issue 26, 163-165 pp.
Vakulenko I.O., Hryshchenko M.A., Perkov O.M. Doslidzhennia etapiv zarodzhennia ta zrostannia trishchyn pry naturnomu vyprobuvanni na vtomlenist [Research of the stages of nucleation and growth of cracks in full-scale tests on fatigue]. Visnyk Dnipropetrovskoho natsionalnoho universytetu zaliznychnoho transportu[Bulletin of Dnipropetrovsk National University of Railway Transport], 2008, issue 21, pp. 266-268.
Kottrell A.Kh. Dislokatsii i plasticheskoye techeniye v kristallakh [Dislocations and plastic flow in crystals]. Moscow, Metallurgizdat Publ., 1958. 255 p.
Nott Dzh. Osnovy mekhaniki razrusheniya [Foundations of the fracture mechanics]. Moscow, Metallurgiya Publ., 1978. 256 p.
Atkinson J.D. The Work – hardening of Copper – Silica: IV. The Bauschinger Effect and Plastic Relaxation. Philosophical Magazine, 1974, vol. 30, no. 6, pp. 1247-1280.
Crist B.W. Comparison of the Hall – Petch parameters of Zone – refined Iron Determined by the Grain Size and Extrapolation Methods. Acta Metallurgica, 1967, vol. 15, no. 5, pp. 809-816.
Garofalo F. Factors Affecting the Propagation of a Luders Band and the Lower Yield and Flow Stressers. Metallurgical Transactions, 1971, vol. 2, no. 8, pp. 2315-2317.
Gleiter H., Chalmers B. High – Grain Boundaries. Progress in Materials Science, 1972, vol. 16, 375 p.
Hollomon John H. Tensile Deformation. AIME, 1945, vol. 162, pp. 268-290.
Holzman M., Man J. Determination of Friction stress in BCC polycristalls. Journal of the Iron and Steel Institute, 1966, vol. 204, no. 3, pp. 230-234.
Vakulenko I.A, Perkov O.N., Razdobreyev V.G. Mechanism of the Effect of the Ferrite Grain Size on the Fatigue Strength of a Low – Carbon Steel. Russian Metallurgy, 2008, vol. 2008, no. 3, pp. 225-228.
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