A356 -T6 best way to do creep test? 1

[maha100]

Iam having a component made of A356-T6.
I would like to study the deformation behaviour of this component within the temperature range of 100°c to 200°c.
Can I start by doing a creep test?
Can anyone suggest me the creep properties of A356-T6 material?
The informations of rupture stress and time to rupture will be very helpful for me.

All advices and views are welcome.

Thanks in advance,
Maha.

 

[met1]

Depending on your application, you might try a PVD coating.

 

[TVP]

maha100,

Can you please provide some additional detail on your application? Specifically, what type of deformation are you investigating? Loss of preload in mechanical fasteners? Plastic deformation due to overload? Creep involves relatively low stresses that are applied for long periods. If your application does not have similar load conditions, then perhaps just tensile testing at elevated temperatures will give you the data you need. Sources for data include the following:

Properties of Aluminum Alloys: Tensile, Creep and Fatigue Data at High and Low Temperatures

http://www.asminternational.org/Tem...=Ecommerce/ProductDisplay.cfm&ProductID=11205

Atlas of Creep and Stress-Rupture Curves

http://www.asminternational.org/Tem...=Ecommerce/ProductDisplay.cfm&ProductID=10554

Aerospace Structural Metals Handbook

http://www.cll.purdue.edu/extendeduniversity/selfdirected/ir/index.cfm?ir=aero

 

[maha100]

Hello TVP
Iam investigating behaviour of a brake housing made of A356 T6.It involves tesnile load of 12 KN to 24 KN.Temperature involved is 20 to 200°C.Stress concentration area is 12 sqcm.My question is while doing a creep test is it better to apply a 24KN tensile load at 200 °C and will I see creep fracture in a period of 1000 hrs.I had an idea that experts would have already dealt with such experiments.I have limited time (3 months) to do this experiment.Thats why I also enquired for further ideas to detect plastic deformation behaviour of my component other than creep tests.I also want to detect the fatigue behaviour of this component.

Thanks in advance,

Maha.

 

[TVP]

I do not think creep testing will provide the data that you need. The load application cycles are short and intense, which does not promote creep. I think high temperature strength and fatigue are the two important characteristics. The first reference that I mentioned in my previous message would have some good data for you.

A quick review of some data that I have (ASM HANDBOOK Volume 2) shows that typical room temperature properties of A356 are 165 MPa yield, 230 MPa tensile, and 3.5% elongation. At 150 C, the properties are 140/160/6 and at 205 C, they are 60/85/18. As you can see, the strength dramatically decreases as you increase above 150 C. This is because the typical aging temperature (T6 temper) for this grade is ~ 155 C.

If I were you, I would do the following:

1. Perform finite element analysis on this brake housing. The analysis should take into account both low temperature and high temperature properties. The stresses will likely be lower for the high temperature load case (because the elastic modulus is lower), but since the strength is lower, this will likely have the highest deformation potential.

2. Investigate fatigue loading history. What percentage of the stresses occur at relatively low temperature? What percentage occurs at high temperature? How many cycles do you need to withstand?

3. You obviously have forces, but stress and strain is what you need in order to solve this problem. Strain gauging the components may provide the necessary physical correlation to the FEA. If fatigue is the most important consideration, you will need more detailed information on defects in the housing-- inclusions, porosity, solidification defects, etc.

 

[maha100]

hello TVP

It was exactly what i needed.
Also I thank you very much for showing me a step to proceed.
It was amazingly helpful.

Maha.