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 Wysłany: Pią 16:10, 17 Gru 2010 Temat postu: ugg boots günstig Determination of residual stres |
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Determination of residual stress about the basics of the second X-ray stress measurement of the basic principles of
2 set to 2G, and sin. The correlation between the straight line and find the slope of the M,[link widoczny dla zalogowanych], the value can be calculated. With sin. Law is a prerequisite for surface x-ray irradiated region in the plane stress state, in most cases the actual determination of the object is in line with this assumption. 3X-ray elastic constants determined in the X-ray stress the basic equation (1O) contains the Voigt elastic constants (1 / 2) s. And S,[link widoczny dla zalogowanych], which is based on equation (7) and ( from macro-elastic modulus E and Poisson's ratio calculated. E and for isotropic materials, stress-strain relationship. However,[link widoczny dla zalogowanych], the selectivity of X-ray diffraction, X-ray diffraction is measured by a crystallographic direction of the elastic strain. At this point the crystal elastic anisotropy will be shown, leading to X-ray diffraction and the measured stress values obtained by the elastic stress values are not equal. To this end, x-ray stress measurement of basic equation (1O) must be replaced by the so-called X-ray elastic constants (1 / 2) S and S, (hk1) diffraction planes to generate the surface index. And the corresponding X-ray stress constant of expression (17) should also be rewritten as K = [(1 / 2) S] (a 1 / 2) cot & (7 / 180) (19) X-ray elastic constants (and X-ray stress constant) to consider the crystal elastic anisotropy effect on the test results, the X-ray stress measurement has very important significance. Different materials in order to obtain x-ray elastic constants can be calibrated by experiments or theoretical calculations of two sources. For the determination of iron-based materials, often, the use of a chromium target K lines selected diffraction planes (211) plane, the X-ray stress constant K value of a 318MPa /(。),[link widoczny dla zalogowanych]。 Other materials, x-ray elastic constants and x-ray stress constant of the literature available [1]. References: [1] EigenmannB, MacherauchE. Roentgenographischeuntersuchungvonspannugszustaendeninwerkstoffen (teil3) [J]. Mat-wissUWerkstofftechnik ,1996,27:427 - 431. Correction: journal start from the fourth series of lectures published the name should be \(Continued from p. 223) in Figure 5a section of the normal direction can always be consistent with the loading direction, which makes the crack load and crack on the load applied to the sample or less, so that the crack tip stress intensity factor Klc easily reach the critical value [Citation. Cross-section in Figure 5b Figure 5a as the cross-section as flat as in the fracture process, the cross section of the law is difficult and the load direction to be consistent, the results on the role of the crack crack crack load and the load applied to the specimen than the difference large, the crack tip stress intensity factor reaches a critical KlC value will not be easy, which appeared in 970 ℃ temperature treatment of samples quenched Klc values higher than 850 ℃ of the phenomenon. Compared with Figure 5b, Figure 5c and Figure 5d cross section is more uneven, which caused material Klc values increased. Similarly, after 1350 ℃ quenched material intergranular fracture occurs when a large area, due to the fundamental law is not crystal plane load direction, making the section method and the load to the hard direction, causing the temperature to rise to 1350 ℃ during quenching, K,[link widoczny dla zalogowanych], c values continue to rise. From the test results, if 45CrNiMoVA high-strength structural steel for structural parts, and during use to ensure that the impact will not be overloaded, the formulation can be more relaxed heat treatment process, because it is quenched in a wide temperature range , yield strength and tensile strength changed slightly, and the fracture toughness increases instead of falling. The quenching temperature of the impact energy of the material is clear, therefore, if required in the course materials have high toughness, it is necessary according to the material properties of heat treatment and the use of the material properties to determine the specific requirements of strict heat treatment process. 4 Conclusion In a certain range of quenching temperature on high strength structural steel 45CrNiMoVA yield strength, tensile strength and hardness of no effect, while the cross-section of material shrinkage, elongation and impact energy is a significant influence. Temperature quenching at 1350 ℃, due to severe material intergranular fracture, resulting in decreased tensile strength. References: [1] Madeleine. Fracture mechanical properties of ferrous materials parameters of Manual [M]. Beijing: Ordnance Industry Press, 1994. [2] Hu Ignition kg. Fracture mechanics and its application [M]. Beijing: Beijing University Press, 1989.
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