I need to have a small weld repair on my 964 motor and the welder is asking me if I know the exact composition of the case.
I know it's aluminum, but does anyone know if there is some sort of mix in there? Like possibly a certain amount of magnesium or any other material that the case is composed of other than straight up aluminum?
Cheers

 

To be exact, it might be better to know what spot on the case is being repaired to help solicit a better answer from someone who knows the composition of the case. My guess is A6061 to T6 spec. If your welder is like "Bobby across the street" then it ain't gonna make a tinkers damn what you tell him. If its a qualified shop it still may not. Also, would help to know is the welder using Tig, Mig, Stick, or even Oxy-acetylene. In any case if you don't have any consideration for the T6 spec ( or whatever the spec actually is) you can use most anything you like. Sorta, red neck engineer it like Nascar repairs. LOL!

 

There is no known info on the alloy used for the engine case. It is definitely not 6061T6 or any billet. The case is a cast part. Most of the alloys used on Porsche cast parts seem to be closer to what we call in the US A356.0T6 although I have never tested the case most of the wheels and other parts are marked showing an Aluminum alloy with 7% silicon and 0.4% mag. A356.0T6 is an aluminum alloy with 7% Silicon, 0.3% mag, 0.2% iron and 0.1% zinc. Although alloys are measured in ranges or max or min quantities of alloying agent.

A356.0T6 is the alloy used for most cast aircraft or military parts in the US. I suspect the case is similar based on what I see. Although it is possible it is closer to 355.0T6 which adds Copper to withstand heat and retains its strength at higher elevated temps. I used to cast engine cases for the NASCAR truck series decades ago out of this alloy. It is an alloy my grandfather pioneered along with ALMag 35 & AZ92 magnesium AKA Dow metal with Dow chemical when he headed Bendix Eclipse Pioneer back in the 30's.

You can always send out some shavings or grindings from the area for chemical analysis. If you do I would be interested in learning what the alloy is. It is also tempered so as said you will destroy the temper if welding the case. Normally a part is heat treated to a T5 solution treatment then welded and artificially aged to full T6 after the welding is done. Make sure he clamps it flush to a table to prevent warpage.

GL

 

I'd either send out a little for checking or maybe you can use one of those fancy metallurgy guns like a jeweler uses. Just point at it and it will tell you.

 

Thanks for all the feedback. I should have been more specific when I started the thread.
This is a 964 engine that was in an accident and the header snapped off a chunk of the threads where the oil supply line threads into the case. Fortunately it was a clean break and I don't see any distortion so it mates up very nicely. Seems to me like a pretty straightforward repair, but don't want to take chances using the wrong TIG rods. The threaded pipe still threads in smoothly when I mate the broken piece up to the case and the threads all still line up nicely and the pipe turns without resistance.
So I was told to clean it, clean it again, and then again. Grind out a little bit of material all along the outside edge of the break to create a "v" so the TIG has something to bite to, and clean it again.
But the welder asked me to find out what that case is made of to determine what type of rod to use.

 

I see what you are saying. Being the oil return connection it probably can be fixed without issue since it isn't under any pressure, however you might consider another option. Porsche went from a threaded insert to an adapter that has an O ring and is held in palce by the bolt adjacent to it.

You might be able to have something made to replace the broken piece and weld it in place using the oil line from a 993.

I have no doubt you can come up with a solution. If you weld the piece in place you can also make a plate that holds the insert or threaded adapter in place taking any strain off of the casting. You can use both threaded holes on either side as well. Just a thought.

GL


993 engine with newer style approach to keeping the pipe in place.

 

Fascinating! IMHO, you need to machine out the area and weld in a bung that can be tapped to the thread size for that fitting. The described quickie fix is not recommended.

As an aside here is some info on A6061 It has a German origin in 1935 hence my guess on the case composition:

Casting 6061 T6 Aluminum6061 T6 aluminum is a popular alloy for casting due to its excellent combination of properties, including:

• High strength-to-weight ratio
• Good corrosion resistance
• Versatility for various applications

Die Casting

Die casting 6061 T6 aluminum is a common method for producing complex shapes and intricate details. The process involves injecting molten aluminum into a metal mold, or die, under high pressure (typically 10,000-20,000 psi) and temperature (around 900°F). This results in a dense, accurate, and durable casting.

Heat Treatment

As-cast 6061 aluminum is often soft and prone to distortion. To achieve the T6 temper, the casting must undergo heat treatment, which involves:

• Solutionizing: Heating the casting to around 980°F (520°C) to dissolve the alloying elements.
• Quenching: Rapidly cooling the casting to around 400°F (200°C) to precipitate the solutes.
• Artificial aging: Holding the casting at a specific temperature (around 350°F or 175°C) for a set period to allow further precipitation and strengthening.

Comparison to Other Materials

6061 T6 aluminum die casting can be compared to die cast ZA-8, a zinc-based alloy. While both materials have their strengths, 6061 T6 aluminum offers better corrosion resistance and higher strength-to-weight ratio.

Challenges and Considerations

When casting 6061 T6 aluminum, it’s essential to:

• Control the pouring temperature and pressure to minimize porosity and ensure proper filling.
• Use a suitable mold material and design to prevent sticking and ensure easy ejection.
• Perform proper heat treatment to achieve the desired T6 temper.
• Consider the potential for warping or distortion during cooling and handling.

By understanding the casting process, heat treatment requirements, and material properties, you can successfully produce high-quality 6061 T6 aluminum castings for various applications.

Further, excellent weldability!:

The 6061 aluminum alloy was developed in 1935 in Germany. Initially, it was referred to as “Alloy 61S”. This precipitation-hardened aluminum alloy contains magnesium and silicon as its major alloying elements.

Key Characteristics

• Good mechanical properties
• Excellent weldability
• Commonly extruded (second in popularity only to 6063)

Tempering

The alloy is available in various tempers, including:

• 6061-O (annealed): maximum ultimate tensile strength ≤ 150 MPa (22 ksi), maximum yield strength ≤ 83 MPa (12 ksi) or 110 MPa (16 ksi)
• 6061-T6 (solutionized and artificially aged): ultimate tensile strength ≥ 290 MPa (42 ksi), yield strength ≥ 240 MPa (35 ksi)

Applications

The 6061 aluminum alloy is widely used in various industries, including:

• Aerospace and defense technology
• Shipbuilding and marine construction
• Automotive and vehicle manufacturing
• Electronic devices (e.g., laptops, smartphones)
• General-purpose structural applications

German Standard

In Germany, the 6061 aluminum alloy is specified as EN AW-6061, which is part of the AlMgSi alloy family. This material is used in various applications, including vehicle, ship, boiler, and tank construction, as well as defense technology and aerospace.

More!:
https://at-machining.com/6061-aluminium-alloy/

 

drola (The OP), please review your photo referencing "Fortunately it was a clean break and...". Its a little worse than you know. See the crack in your photo with my blue arrow.

This crack is heading near one of t he 4 mating bolts to the trans. Where does it end?
An expert repair is recommended.

 

Fortunately it ends right there. We added some meat to reinforce it.

And here is the outcome. Welded up pretty nice. He added lots of material which is fine with me. I filed the mating surface flat so the crush washer will do its thing. I plan on getting some jb weld or marine tex and filling the cracks on the inside of the threads, then putting more of it on the threads of the oil line that screws in there, give a good snug, and never touch it again. Fortunately, the oil line has its own nut and I can tighten it without needing to do anything more than holding this one in place.
I hope it works. It'll probably be about a month before I get this motor in my car so until then I'll just have to wait....

 

Glad you got it fixed. The threads internally still look mangled, did you make sure you can still thread something in there? You could always just weld an AN fitting there, eliminate the threads and run nice hose.

 

Interesting internet info. As a retired 30 year veteran and 1st tier supplier of Aluminum and Magnesium sand castings for the US aerospace and defense industries, this is a first I have heard of using 6061 for castings like this. 6061 has poor fluidity due to its low silicon content. It is commonly used for plate, pipe tubes etc. Mostly parts are machined from it and not cast although I have been retired for 10 years so times may have changed. Unless you have info other than what is on the internet I still don't believe it would be 6061. I know of one foundry that cast it but they used a centrifugal process but for small parts only. If it was used it would need to be Die or Pressure Cast but again not in sizes this large and it would never flow properly as a sand casting.

If you have any info stating that 6061 was actually used for these cases I would be interested in seeing it. Although like the rest of the cast parts Porsche used I suspect the Si content is higher for fluidity and would be closer to the 356 or 355 alloys.


@drola I do agree with @Bustednukel I would be hesitant to use it like that. Without securing the pipe I suspect over time vibration will cause the weld to give.

 

Cobalt, certainly defer to your knowledge and experience. A casting nimrod here. My guess of 6061 T6 which I posted after noting that no response to the OP had occurred after a couple days. Here is a link to Miguss Peter Mies GmbH, Hellinghaus Germany who cast EN-AW6061 using DIN standards. Thought about emailing them concerning the 964 case material; its really a small world, might have info or a lead to the answer. Perhaps it might be better for you to ask because of your expertise. In the past I have contacted those in Germany who were knowledgeable in materials manufacturing and received informative replies.

drola, added a new blue arrow to same crack in your finish photo that has now expanded due to welding heat. Will likely propagate further in the general direction of the mating stud to the trans.

 

Presumably the block was repaired correctly, though it does look a little ugly, and the fact the welder was asking you to confirm, is a little suspect. But they should have drilled small holes at the end of those cracks to prevent them furthering, prior to welding.

I still would have just welded an AN fitting onto that neck.

 

It is all good. It is funny people think casting parts is easy but it usually isn't. There is so much that can cause problems. I was, what my customers called a sliced bread shop. I had the pleasure of making the most complicated parts in the smallest quantities that the larger shops had no interest in dealing with. So I made the 5-10's and 1000 units vs the 10,000 on up. The fun part was I had to get it right the first time and every time. No doubt times have changed and advancements made since the 90's. They are 3D printing and casting alloys in ways we could not do back then. It is possible that they have found a way to use 6061 more effectively today but back in the 90's most of Porsche's castings were rudimentary and I hate to say not the best quality. Adequate to do the job but not the level I was held to for the DoD or any aerospace contractor..

I have a spare case. If I can find a place to remove some shavings I can send them out for wet analysis since I don't have a large enough piece to do a spark test. It would be good to know for future reference in case this happens to someone again. It is interesting that you reference Miguss Peter Mies GmbH, Hellinghaus Germany When I purchased my house back in 1999 my neighbors son who I had just met moved to Germany to work for them. He was a very talented foundry man but IIRC they were not at the level they are today. I no longer have his contact info or even know if he still works for them but If you get any info from them please post it. Always looking to learn everything there is about these cars and usually learn something new everyday.

I usually see the trans cases fail from accident damage and also the fork lugs can crack off and they usually get weld repaired or they get machined off and new pieces welded in place but you need to hone the opening to precise dimensions. Without the inside of the opening welded and tapped I wouldn't trust this personally. I would use the 993 approach. You can weld a plate to the threaded insert and bolt it to the case. This would at least insure it doesn't break off easily in case the weld didn't penetrate properly. Then use a sealant like 574, Threebond or other engine sealant to make sure that oil doesn't make its way through any porosity that is left from the welding process.

GL

 

Cobalt, sent this off to Miguss by email. They will certainly reply.
My admin skills are pretty good and with a thin veneer of expertise. Shouldn't we also send one to Porsche AG? Certainly the group knowledge here has a contact.

"Hello folks at Miguss,

While researching for composition of Porsche engine cases, your company was identified as expert in casting EN-AW6061. I have guessed that this process may be similar to the one used by Porsche on their 911 model produced from 1989 through 1994. Porsche's internal code for that model year's car was 964. Our interest in the identification of the case material and process to manufacture is related to the proper repair of cracks or other damage. Particularly the fill material for such repair needs to be identified in addition to the actual case material.

Our interest in this project is shared with others who are passionate about Porsche cars on Rennlist. Presently we are trying to avoid mis-repair of these cars and seek any knowledge or direction you might care to offer. We believe an exact answer may be resident with folks like those at Miguss and your community.

Many thanks and best regards,
Signed "