A240 vs A276/A479

[aidrock]

Please bear with my explanation below as I am a Civil Engineer working in a custom equipment building shop currently and am still working through all of the proper terminology.
I am working on a project that specified 1.00 x 4.00 x 9.0 Type 304L/ASTM A-240 for a certain part that is final machined to a size of 1.00(STK) x 4.00 x 8.50. There are a few holes that are added thru the 1" thickness - I believe the part is used as a tie-down for a transmission for a helicopter during transport, not during actual usage.

We bought the above size, but in A276/A479 as that is the specification for bar (4" width) vs plate that we would have had to burn/cut here. Our client, whom is the one actually contracted with the helicopter mfg, is rejecting this material and citing the incorrect ASTM designation. The material we bought came with certifications - all Mechanical requirements exceed A240/276/479 and Chemical comp's fall within guidelines.

It is my argument that the only difference between these three ASTM specifications is the designation of the material as Plate, Bar, Shapes, etc and does not have any bearing on the characteristics of the material itself.

Any thoughts or comments on this (sources comparing the two/three would be extremely helpful) would be greatly appreciated.

Kind regards,
Aidan

 

[EdStainless]

It is usually better to ask about these issues up front.
While the product may meet the strength there could be other issues (though I doubt it).
When they made a 100 of these they cut them from plate, it would be a lot less expensive.
The only real issues other than strength would be testing, and I don't believe that there is any NDT requirement for plate.
Good luck, but didn't comply with the PO.
Live and learn

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Plymouth Tube

 

[aidrock]

Ed,
Thanks. I understand about all of the purchasing issues and am not looking for a lesson on how to buy and really there is no reason to chastise me for it - that is not the subject of my request. I am not looking to "get one over" on our client, but am hoping for someone to actually look at the information and make a decision instead of just saying "no" because the spec number is different, but not the properties.

The product meets/exceeds ALL Mechanical/Chemical requirements and as far as I can tell is made by similar/same processes.
Aidan

 

[EdStainless]

Actually not meeting the spec number is a complete failure.
The bar could be made by a very different process than the plate.
It could have been strand cast very near final size and given a light hot finish pass. In this case it could be an inferior product.
In reality is probably no different than material cut from plate (that can have its own issues, such as which way was it cut).
All that I was saying is that the ASTM spec number is the basis of the contract.
If he had just called out S30403 and some minimum mechanical properties then all would be fine, be he chose to invoke a specification. You don't get an option.

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Plymouth Tube

 

[aidrock]

Your thoughts on forming is exactly what I was hoping to find out here - are these materials identical or not??? I understand that not knowing the application makes this a more difficult question to answer as to the comparativeness of the materials.

If someone with experience in these material properties/issues could please chime in I would very much appreciate the help.

If the material is unacceptable as an alternative then it is our mistake and we will accept that and buy the appropriate material, but if it can be acceptable and some engineer or buyer somewhere is just rejecting it because of policy then I have an issue with that.

 

[arunmrao]

Ed, Zillion stars for your patience and control. OP should appreciate the suggestions made and not feel that he is being chastised.
There has been a nonconformity, and one should try and find a way out by discussion and not confrontation.

Sorry, if it offends some.

I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[aidrock]

I am still looking for these suggestions - none have been stated . . .
I agree 100% that we ordered the "wrong" material, but am simply asking if it could be the "right" material.
I am attempting to begin a discussion with our client and just want to make sure I have all the facts so that I am presenting an accurate case - if the A276/479 is inferior, I have stated that I have no issues with re-buying the correct product per their drawings. I just want to know why it is not acceptable - saying "because" is what my 2.5yr old does . . . or me to him when I don't have a real response!

Thanks to all for the posts - now can anyone answer about actual material/chemical/physical differences between the specifications?

 

[metengr]

Unfortunately, this is really a contractual problem, and not a technical problem between you and your client. You need to discuss with the client and try to persuade them. If they do not agree, you have little recourse. Sorry, but that is the reality of the situation.

 

[MagBen]

If your customer insists rejection, you have to eat it. No augument about that.

From a pure technical viewpoint, though, I donot believe they have a big difference. As a matter of fact, a bar product could be a little superior than a plate in terms of uniformity. For the dimension you referenced, the bar was probably pressed from both directions, while a plate is normally rolled through the thickness only.

 

[aidrock]

metengr - you are missing the point of my question. Ignore the error that we made in ordering the "wrong" material - that is not material (pun intended) to this discussion.

MagBen - Thank you for actually looking and answering the question I have (What are the differences, if any, between the specifications and the materials produced to them?). That is all I have been after here is to answer that question.

 

[EdStainless]

Is the material suitable, technically; Maybe or maybe not.
It could be better quality (if the bar was made with high reduction ratios) and have more uniform properties.
Of the bar could have been made with very low reduction and have serious centerline issues and be clearly inferior to cut plate.
Not that cut plate is a good idea without some further constraints on process. As an example you have a piece 1"x4"x8".
It could be cut L or T from a 1" thick plate, or it could be cut L or T from a 4" thick plate, or it could be cut Z from a 8" plate. These could be very different products depending on how uniform the plate is.
In the aerospace business they require tracking for the L and T directions every time a plate is cut.

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Plymouth Tube

 

[metengr]

aidrock;
I have a feeling there is more to this story regarding the material specification specifically requested by your client, which either you are not privy to or not made aware from a design/end use. Take a closer look at what is required between the two material specifications other than chemical composition and properties.

 

[bmoorthy]

1) Comparing Heat treatment conditions
A) An item (SS 304) procured under A276 can be
Condition A—Annealed
Condition S—Strain Hardened—Relatively light cold work
Condition B—Relatively severe cold work
B) An item (SS 304) procured under A 479 can be
Annealed
Strain Hardened Level 1
C) An item (SS304) procured under A240 shall be solution annealed

If the A276/A479 bars procured by you are in Annealed condition, then your problems are reduced to substantial degree.

2) Is there an compelling reason for selecting one product form over the other?
In the following industry some times (depending on the end application of the item) emphasisis on selecting a particular product form may be given by design personnel due to concerns related to Material Orientation and Anisotropy.
aa)Aerospace industryin
bb) items that are subject to fatigue
cc) where brittle fracture is a concern
dd) Cryogenic service

Some of the The forming process of a material, such as drawing, extruding, rolling, or forging, can have a great effect on the microstructure and texture (preferred grain orientation) of the material. Additionally, the fracture toughness of a material is affected by the microstructural and mechanical changes a material
undergoes through processes such as heat treating. Material anisotropy (or simply anisotropy) is a term used to describe the dependence of material properties, such as fracture toughness, yield strength, and elastic modulus, to the texture.When a material has mechanical properties that are independent of direction, it is said to be isotropic. Conversely, if the material has mechanical properties that depend on a particular (or preferred) orientation(s), it is said to be anisotropic.

From what you have described as end application "tie-down for a transmission for a helicopter during transport, not during actual usage", it is not clear as to what the design stadard is, hence, in my view, for you to have an objective conclusion in this matter, you need to know the design standard based on which the personnel who gave the requirement, put the dimensions in the first place if the dimension and product specification was given based on past experience by your personnel or your cleint, you may call him for a dialogue and ask him the exact technical rationale for such rejection and offer mitigation measure by destroying a couple of pieces (as assurance testing) by subjecting the items to test that the client wants as assurance.

 

[OGMetEngr]

Also, it may or may not matter in your case, but A276/A479 both reference A484 for annealing which allows the use of hot rolling to be counted as the "in-process anneal". A240 instead references A480 which requires a separate solution anneal process. I've seen the results of this first-hand, with A479 bar unable to pass intergranular corrosion testing, while the A240 is better able to pass.

Just another example of how different processing requirements in these ASTMs make a difference.

 

[Cleandive]

The item appears to be component in rigging

 

[aidrock]

A HUGE THANK YOU to both bmoorthy and OGMetEngr for taking the time to answer the question posed. I very much appreciate your feedback on this and am waiting to see if the substitution will be approved.