Question

Describe the conduct of a typical creep test

Answer 1

A Creep test measures th pressure rate of deformationof a given material at high temperatures.

Creep test is conducted using a tensile specimen to which a contant stress is applied at constant temperature to a constant load and recording the output strain.

it has three stages:

1) the Primary creep stsrts at a fast rate and slows with time.

2) The Secondary creep has a uniform rate of speed.

3) The Tertiary creep has an accelerated creep rate and breaks when the material is fractured.

Testing is generally carried out in air at atmospheic pressure and in vacuum chamber for the material which react with air .

The Creep test has the objective of pecisely measuring the rate at which secondary or steady state creep occurs.Ther are two variations of the creep test one is the creep rupture test and the stress rupture test.Both of these tests arecontinued until the specimen fails .

In the creep rupture test the amount of creep that has occured at the point of failure is recorded and expressed as percentage strain.

The stress rupture test gives the time to rupture at a given time and temperature.

CONCLUSION:

It enables the designer to calculate how the component will change its shape during service and hence to design its creep life.