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疲劳试样的制备对所测定的疲劳性能有直接的影响。从金属的疲劳过程中可知,疲劳源总是起源于造成应力集中的表面处。所以,表面上的刀痕或划伤都可能成为服役时应力高度集中的疲劳源。因此,试样表面状态是影响疲劳性能的决定性因素之一。为了使试验结果具有可比性和可靠性,必须制定一个合理的表面加工方法。现行的冶金部标准YB40-64“金属弯曲疲劳试验法”只规定试样尺寸及光洁度。国内对等截面光滑试样均采用横向磨削。因此,往往因试验数据分散,用升降法无法求出较精确的疲劳极限。文献规定当试样截面已机械加工或研磨到标称尺寸时,应该进行抛光,抛光一般应沿试样纵向进行。
Fatigue sample preparation has a direct effect on the fatigue properties measured. As we know from the fatigue of metal, the source of fatigue always originates at the surface where stress is concentrated. Therefore, the surface of the knife marks or scratches may become a service life stress is highly concentrated source of fatigue. Therefore, the surface condition of the sample is one of the decisive factors affecting the fatigue performance. In order to make the test results comparability and reliability, we must develop a reasonable surface processing methods. The current Ministry of Metallurgical standards YB40-64 “metal bending fatigue test ” only specifies the sample size and finish. Smooth cross-section of the domestic samples are horizontal grinding. Therefore, often due to the dispersion of test data, with the lift method can not find a more accurate fatigue limit. The literature provides that when the specimen cross-section has been machined or ground to the nominal size, it should be polished, polished generally should be along the longitudinal direction of the sample.