AlSi7MgCu need a british equivalent. 1

[etch]

Im looking for a british equivalent of this alloy, my guessing would be LM4.

Any ideas, would be helpful.

thanks in advance

 

[TVP]

Alloy designation LM4 is referenced in the specification BS1490. The same alloy is given the designation EN AC-45200 in the specification EN 1706. The nominal chemical composition is as follows:
Cu- 4.5 to 6%
Si- 2.5 to 4%
Mn- 0.2 to 0.55%
Mg- 0.40% max
Zn- 0.55% max
Fe- 0.8 max

Alloy designation LM25 from BS1490 is closer to your stated target of AlSi7CuMg (EN AC-42000 alloy designation in EN 1706). The nominal chemical composition is as follows:
Cu- 0.2% max
Si- 6.5 to 7.5%
Mn- 0.35% max
Mg- 0.20 to 0.65%
Zn- 0.15% max
Fe- 0.55% max

 

[etch]

ah. well i guess i should have expanded a bit more, i have been given three spec to cross reference

AlSi7Mg which is as close to LM25 as you can get.

AlSi7MgCu which if the above is Lm25 then this cant be.

And

Alsi8Cu3Fe which is close to LM24

the last two are for cylinder heads and blocks so i guessed LM4 and lm24, with AlSi8Cu3Fe being high pressure die cast. The other named as just cast.

This is the bane of my life, getting technical drawings from our sales manager, and the drawing stating some spec that was probably agreed over the phone on a Friday afternoon after a liquid lunch, and subsequently put onto a drawing.

Another one i have been asked about is LM200, now firstly i checked that it wasnt a typo (You know what Engineers are like, JOKE!!) and confirmed that it wasnt LM20. So any ideas on this one?

 

[TVP]

Ok, apparently we are in need of some clarification here. AlSi7Mg and AlSi7MgCu are designations from obsolete specifications like DIN 1725-2. EN 1706 is the superceding document for aluminium foundry alloys. Within this specification there are three "Alloy designations" that fall under the AlSi7Mg "Alloy Group", which can be referenced by a Numerical designation or a Chemical symbol designation:

Numerical Chemical symbols
EN AC-42000 EN AC-AlSi7Mg
EN AC-42100 EN AC-AlSi7Mg0.3
EN AC-42200 EN AC-AlSi7Mg0.6

All three of these alloys contain the same amount of Si-- range is 6.5 to 7.5%. The Cu content is quite different-- alloy 42000 allows for 0.20% Cu in castings (0.15% in the initial ingot), alloys 42100 & 42200 only allow Cu up to 0.05% (0.03% in the ingot). BS1490 alloy LM25 allows for Cu to a maximum of 0.20, which is why I stated that this was the appropriate BS equivalent. The three AlSi7Mg alloys differ considerably in other elements like Fe, Mn, Ni, Zn, Pb, & Sn.

I have no idea about LM200. I can only conclude that your sales people and/or the customer are confused and/or ignorant. I agree that it is a major frustration dealing with people that aren't precise in their material specifications. Quoting AlSi7Mg without appropriate attribution of the industry standard (EN, DIN, etc.) only leads to this type of confusion, and obviates the necessity for many of the details (quality control, mechanical properties, etc.) that these standards require. If you have any further questions, please feel free to post again. Best of luck.