[請益] 拉伸試驗的拉伸速率

看板Mechanical (機械)作者shoppinglin (瞎拼)時間15年前 (2010/08/26 01:57)推噓0(0推 0噓 0→)

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目前是看最新版的E8/E8M 以下文字有點多可先直接看段落下方中文擷取部分文字因為我有點被搞混到底想知道YS UTS ELONGATION 的速率規定是上限還固定還下限 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. 上限為1/2的決定YS速率or1/4的決定UTS用速率兩者較小值? 還是說另外有規定specified YSmin的速率為多少? The speed above this point shall be within the specified limits. 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. 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. 想同時取得YS UTS的機性應用同一種方法及速率(但之後卻又分別有規定? ====================================================== 7.6.3.2 Control Method B - Rate of Straining Control Method for Determining Yield Properties — In this method, the testing machine shall be operated in closed-loop control using the extensometer signal. The rate of straining shall be set and maintained at 0.015正負0.006 mm/mm/min [in./in./min]. NOTE 23—A Rate of Straining at 0.005 mm/mm/min [in./in./min] is often required for aerospace, high-temperature alloys, and titanium applications and when specified, must be followed rather than the requirement above. 這裡看不太懂為什麼可以是例外? 前一段應該是0.009~0.021的規範 ====================================================== 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正負0.003 mm/mm/min [in./in./min] of the original reduced section ====================================================== 7.6.4 Speed of Testing When Determining Tensile Strength— In the absence of any specified limitations on speed of testing, the following general rules shall apply for materials with expected elongations greater than 5 %. 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. ====================================================== 這裡是說如果也有要測得YS就依照YS規定的速率嗎? 不過似乎認識的人也都不太在意到底速率多少可能就說 "金屬喔大概就strain 10的-3次方/sec左右吧結果就有些拉個2分鐘有些拉個20分鐘想請益大家是看材料決定還是看學長姐或老師有規定? 謝謝 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 123.204.21.128