Effect of temperature on features and micromechanisms of fatigue crack growth in boiler steels
- 25 Downloads
An increase in test temperature above room temperature leads to a decrease in crack growth rate in steels 15Kh2NMFA and 15Kh2MFA on the low-amplitude section of the fatigue curve and an increase in this rate in steel 15Kh2NMFA on the medium-amplitude section.
Intergranular fracture is active as a fracture micromechanism at room and low test temperatures and crack growth rates greater than 10−6 mm/cycle. The contribution of the intergranular mechanism to fatigue crack formation in the steels at room temperature is greatest (up to 40% of the total area of the fracture surface) on the medium-amplitude section of the curve, at values of Kmax ≈ 20 MPa·√m.
An increase in test temperature from 273 to 673 and 623°K, respectively, for steels 15Kh2NMFA and 15Kh2MFA leads to disappearance of intergranular fracture due to a reduction in the grain-boundary strength of the steels and to an increase in the SIF at which secondary microcracks appear.
KeywordsGrowth Rate Fatigue Fracture Surface Fatigue Crack Test Temperature
Unable to display preview. Download preview PDF.
- 1.O. P. Ostash, S. Ya. Yarema, and V. A. Stepanenko, “Effect of low temperatures on rate and microfractographic features of fatigue crack growth in aluminum alloys,” Fiz.-Khim. Mekh. Mater., No. 3, 26–30 (1977).Google Scholar
- 2.A. Ya. Krasovskii, Brittleness of Metals at Low Temperatures [in Russian], Naukova Dumka, Kiev (1980).Google Scholar
- 3.V. T. Troshchenko, B. A. Gryaznov, V. A. Strizhalo, et al., Methods of Studying the Resistance of Metals to Deformation and Fracture under Cyclic Loading [in Russian], Naukova Dumka, Kiev (1974).Google Scholar
- 4.P. V. Yasnii, “Methods and certain results of studying laws of fatigue crack growth in plane bending at low and high temperatures,” Probl. Prochn., No. 5, 78–81 (1980).Google Scholar
- 5.“Standard test method for plane-strain fracture toughness of metallic materials (É399-74),” in: Annual Book of ASTM Standards, Pt. 10, American Society for Testing and Materials, Philadelphia (1976), pp. 471–490.Google Scholar
- 6.G. P. Cherepanov, “Technical cohesive strength of pressure vessels,” Zh. Prikl. Mekh. Tekh. Fiz., No. 6, 90–101 (1969).Google Scholar
- 7.O. P. Romaniv, Ya. N. Gladkii, and Yu. V. Zima, “Effect of structural factors on the kinetics of fatigue cracks in structural steels,” Fiz.-Khim. Mekh. Mater., No. 2, 3–15 (1978).Google Scholar
- 8.T. A. Gordeeva and I. P. Zhegina, Analysis of Fractures in Evaluating the Reliability of Materials [in Russian], Mashinostroenie, Moscow (1980).Google Scholar
- 9.T. Ekobori, Scientific Principles of the Strength and Fracture of Materials [in Russian], Naukova Dumka, Kiev (1978).Google Scholar
- 10.S. Kotsanda, Fatigue Fracture of Metals [in Russian], Metallurgiya, Moscow (1976).Google Scholar
- 11.C. D. Beachem and R. M. Pelloux, “Electron fractography — means of studying fracture micromechanisms,” in: Applied Problems of Fracture Toughness, ASTM (1965).Google Scholar
- 12.O. P. Romanyv, Yu. V. Zima, and G. V. Karpenko, Electron Fractography of Reinforced Steels [in Ukrainian], Naukova Dumka, Kiev (1974).Google Scholar