自己解决了问题 帮自己回po一下 希望能帮助到有用到的人 ※ 引述《shoppinglin (瞎拼)》之铭言： : 目前是看最新版的E8/E8M : 以下文字有点多 可先直接看段落下方中文 : 撷取部分文字 因为我有点被搞混到底想知道YS UTS ELONGATION : 的速率规定是上限还固定还下限 : 7.6.3 Speed of Testing When Determining Yield Properties— : Unless otherwise specified, any convenient speed : of testing may be used up to one half the specified minimum : yield strength or up to one quarter of the specified minimum : tensile strength, whichever is smaller. : 上限为1/2的决定YS速率or1/4的决定UTS用速率两者较小值? : 还是说另外有规定specified YSmin的速率为多少? 这里应该是说在应力到达1/2YS or 1/4UTS(看哪个小) 之前 速率并不重要 都可以 : The speed above this point shall be within the specified limits. 超过这个应力值之後 就必须加以规范(有上下限) : If different speed limitations are required for use in determining : yield strength,yield point elongation, tensile strength, elongation, : and reduction of area, they should be stated in the product specifications. 用不同速率决定不同性质时必须加以说明 : In all cases, the speed of testing shall be such that the forces : and strains used in obtaining the test results are accurately indicated. : Determination of mechanical properties for comparison : of product properties against a specification value should : be run using the same control method and rate used to : determine the specification value. : 想同时取得YS UTS的机性应用同一种方法及速率(但之後却又分别有规定? 应该是比较同性质时要取用一样的拉伸速率 : ====================================================== : 7.6.3.3 Control Method C—-Crosshead Speed Control : Method for Determining Yield Properties– : The testing machine shall be set to a crosshead speed equal : to 0.015正负0.003 mm/mm/min [in./in./min] of the original reduced section : ====================================================== : 7.6.4 Speed of Testing When Determining Tensile Strength— : When determining only the tensile strength, or after the yield behavior : has been recorded, the speed of the testing machine shall be set between : 0.05 and 0.5 mm/mm [or in./in.] of the length of the reduced section : (or distance between the grips for specimens not havinga reduced section) : per minute. ====================================================== 後来才看到早该发现的ASTM A370 附上速率的一小节原文 7.4 Speed of Testing—The speed of testing shall not be greater than that at which load and strain readings can be made accurately. In production testing, speed of testing is commonly expressed: (1) in terms of free running crosshead speed (rate of movement of the crosshead of the testing machine when not under load), (2) in terms of rate of separation of the two heads of the testing machine under load, (3) in terms of rate of stressing the specimen, or (4) in terms of rate of straining the specimen. The following limitations on the speed of testing are recommended as adequate for most steel products: NOTE 2—Tension tests using closed-loop machines (with feedback control of rate) should not be performed using load control, as this mode of testing will result in acceleration of the crosshead upon yielding and elevation of the measured yield strength. 7.4.1 Any convenient speed of testing may be used up to one half the specified yield point or yield strength. When this point is reached, the free-running rate of separation of the crossheads shall be adjusted so as not to exceed 1/16 in. per min per inch of reduced section, or the distance between the grips for test specimens not having reduced sections. This speed shall be maintained through the yield point or yield strength. In determining the tensile strength, the free-running rate of separation of the heads shall not exceed 1/2 in. per min per inch of reduced section, or the distance between the grips for test specimens not having reduced sections. In any event, the minimum speed of testing shall not be less than 1/10 the specified maximum rates for determining yield point or yield strength and tensile strength. 7.4.2 It shall be permissible to set the speed of the testing machine by adjusting the free running crosshead speed to the above specified values, inasmuch as the rate of separation of heads under load at these machine settings is less than the specified values of free running crosshead speed. 这句好乱= = 应该是指空拉的速率调到规定值 不过要知道在有试片时会略低於此值? 7.4.3 As an alternative, if the machine is equipped with a device to indicate the rate of loading, the speed of the machine from half the specified yield point or yield strength through the yield point or yield strength may be adjusted so that the rate of stressing does not exceed 100 000 psi (690 MPa)/min. However, the minimum rate of stressing shall not be less than 10 000 psi (70 MPa)/min. 这个就要看reduced section长度 跟young's modulus 去推算strain rate or grip separation speed PS 钢材大约E=200GPa 原来有这麽多东西我现在才发现= = 我用的strain rate 大约是0.24/min 大概符合决定UTS的速率 不过完全大於690MPa/min(约=0.00345) 不过拉出来E反而是偏低很多 可能是因为我用螺纹的试棒有空隙一开始的strain不是从reduced section来的 --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 123.204.71.22 ※ 编辑: shoppinglin 来自: 123.204.71.22 (10/06 11:30) ※ 编辑: shoppinglin 来自: 123.204.71.22 (10/06 11:30)