Tensile Test

[kishore0721]

Hey Guys,

i am new to doing tensile test and i have a simple question
i am testing some aluminum samples of 2024-T851 and 7075-T6 and i read the ASTM E 8 Standard for tensile testing it doesn't specifally mention the cross head speed for testing different material and i was wondering what rate to use? and i was thiking for a strain rate of 0.05 in.in./min.

i am using an MTS test machine using a 20KN load range and a 1 in. MTS extensometer mine a round bar with 0.25 in. diameter.

 

[CoryPad]

The reason the crosshead speed isn't mentioned is because the sample geometry will affect the stress/strain rate, which is the important factor.

Here is an excerpt from ASTM E 8:

7.6.3.2 When performing a test to determine yield properties, the rate of stress application shall be between 10 000 and 100 000 psi/min.

You can perform the calculations yourself to see what you need to set for the crosshead speed.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[EdStainless]

My practice with new tests is always to test a range of strain rates with identical bars. You will find that most of them give you identical data, and the higher strain rates will be squirrelly. Alloys with high strain hardening factors will be very sensitive.
Make sure that you not only look at the yield and UTS, but the modulus also. Often variation in E are an indicator that the test is lees than accurate.

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