AMS2771 - Soak Time Interpretation (Thermal Conditioning) - T6 or T61?

S

Sorin

AMS 2771 page 11 (and 12) Table 2

Soak times are mentioned either as a single value (and in this case it says minimum) or as a range.

Also, the note 13 says that "Soak times are recommendations, other times may be required depending upon casting configuration and property requirements"

Example:

For A356.0 we have

T6 - 310 deg F - Soak time 3-6 hours
T61 - 310 deg F - Soak time 6-10 hours

If a customer requires T6 condition but in order to obtain the mechanical properties I have to maintain (soak time) for 7 hours, do I certify that as a T6 or T61?

Thank you in advance for help
 
A

anil123

In this case it is better to discuss the matter with customer and finalaze the manufacturing process plan and get the approval from customer. You should not assume anything, get the confirmation by convencing customer regarding the issue.
 
P

Phiobi

AMS 2771 page 11 (and 12) Table 2

Soak times are mentioned either as a single value (and in this case it says minimum) or as a range.

Also, the note 13 says that "Soak times are recommendations, other times may be required depending upon casting configuration and property requirements"

Example:

For A356.0 we have

T6 - 310 deg F - Soak time 3-6 hours
T61 - 310 deg F - Soak time 6-10 hours

If a customer requires T6 condition but in order to obtain the mechanical properties I have to maintain (soak time) for 7 hours, do I certify that as a T6 or T61?

Thank you in advance for help

Thats a good question and one faced by me all the time. The way I have been looking at it is that we provide a mechanical result which confirms the heat treated condition, therefore if the required heat treatment (to hit the customers required mechanical properties) does not match the spec, I tell them. We then agree to state the base alloy and have the required mechanical properties entered into the contract instead of the heat treated condition.
 
A

anil123

Actually when we heat any material due to temeprature and soaking time we get some properties which is also depends on material under consideration.
Hence as a metallurgist, we have to convince the customer with basic principles of metallurgist. definately he will agree.
 

Caster

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AMS 2771 page 11 (and 12) Table 2
For A356.0 we have
T6 - 310 deg F - Soak time 3-6 hours
T61 - 310 deg F - Soak time 6-10 hours
Thank you in advance for help


I did some research into the source of these heat treat time and temperature tables, and it seems they were developed by ALCOA around the WWII time frame. ALCOA has since disowned these tables.

Since that time the rise of lawyers/liability has led to a situation where these original tables are copied but no one dares publish new values in case a component fails and their company is dragged into the lawsuit.

So the times/temperatures listed are very dated and do not take into account metallurgical advancements like modification, chill casting, higher temperature aging and so on.

I think you are right to heat treat to the required properties, and worry less about what it is called.

Do you cut test bars from test castings or are results from separately cast test bars? That is another whole can of worms.
 
P

Phiobi

We do both. We use integrally cast bars for routine tests but we also perform cut up analysis. If customers allow then we will append to a casting so that we do not need to destroy a whole casting.

One of our customers calls for 1 cut up for each heat treatment load, we can only HT 6 parts in any 1 load! Very expensive. A pain if we need to resolution!!!
 
A

anil123

The normal and pricipally ok practice is to load a HT charge along with cut sample. Then cut sample is tested for metallurgical properties which are the indicative result for that HT charge. This practice is used for each Heat
 
S

Sorin

Thank you all for advice....it was more or less what I had/have in mind...I think I just wanted to see if I am on the right path...Thank you again...
 
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