By -
Date 11-30-2001 20:18
I think that the starting point here has to be, to know what material you are trying to weld.
You say that it is some kind of cast steel. You also say that you are welding it with 316 filler. This would only make sense if the materials being welded was 316 S/Steel.
If the material was ordinary cast C/Steel, then you will naturally tend to pick up cracking problems. This would especially be so because you have a gas that would tend to give high penetration, and therefore high dilution. (Gas contains both C02 & He)
If you have a S/Steel, then the cracking problem would almost certainly come from the oil contamination that you are speaking about. It would be hot cracking.
My recommendation would be:
1)Find out for sure what material you are welding. Once you know this, you can make sure that your filler and gas is suitable.
2)Get rid of your contamination. This can be done by a suitable solvent cleaning method, or vapourizing the contaminants by heating up to a high temperature.
3)If you still have contamination problems, then use a fluxing process such as Flux Cored Arc Welding. (FCAW)
4)If you do all of the above, and still experience problems, it may be that your castings are not clean. You therefore need some sort of quality control on the casting composition.
If you find out what materials you are welding together, then let us know. Maybe we can then give more precise advice.
Regards
Niekie Jooste
Thanks for the reply. I sure wish we knew exactly what the material of the cast steel center is but I do not know how to find this out. These are standard carbon steel housings made by firms such as Dana, Eaton, GM, Ford etc.
I am fairly confident we are getting rid of 90% of the contamination by heating and brushing. We also stand the housings on end when welding to make sure that any oils run away from the weld area. We have no control over the casting quality and these housings have usually been in service for many years.
We have welded these housings with ER70S-6 filler but a lot of the time the weld will crack at the edge next to the cast. Would an ER70S-2 allow more flexibility and help to prevent this?
Thanks again!!!
By -
Date 12-03-2001 18:02
Establishing the composition of the material is usually quite easy. There are many firms around that perform on-site spark emmission spectroscopy. It is quick and easy, but can cost a bit. (Although usually not that excessive that it is prohibitive.)
You also seem to indicate that the castings are not new, but used. I thought you were talking of a production line, but it appears that you are looking at repair welds. Is this correct?
I would still suggest getting the material analysed. Sometimes this is not necessary because there are adequate markings on the casting to identify it. Make sure if your casting has such markings. Contacting the supplier of the castings (Ford etc.) should also be a means of identifying the material.
You stated that the weld cracked at the edge, next to the cast. I am not sure what you mean by this. Do you mean that it is cracking in the toe of the weld?
Assuming that the material is a cast carbon steel, this may be cold cracking.
If you want to "just go for it" and seeing what results you get, without worrying too much about the possible failure consequences, (A bad idea if you are welding on axles!) then weld it with a fluxing process such as FCAW or SMAW using a E312 electrode. (29/9) This electrode has a high amount of austenite that tends to absorb the H and reduces cold cracking problems. It also has a high amount of ferrite that can absorb impurities without causing hot cracking.
If however, you have an alloyed steel, the filler is irrelevant. Your heat affected zone (HAZ) will be hardened. The same will be the case if the casting is cast iron.
Getting rid of 90% of the oil is usually not nearly enough. Even traces will lead to cold cracking in C/steels and hot cracking in S/Steels. I do not believe that moving to ER70S-2 will have any real benefits in your situation.
The first rule of welding is: Know what material you are welding! (Even if you are only making an educated guess.)
Hope this helps
Regards
Niekie Jooste
I think this is a cold crack.
If you use 316L to weld carbon steels, we will have very hard martensitic weld metal(refer to Schaeffler diagram). We can have cold crack at the bead.
If you use ER70S-6 with mixed gas(80% Ar), we will have also hard weld metal due to high amount of residual Manganese and Silicon.
From this point of view, it is recommended to use ER70S-3 or 2 which has less amount of Mn and Si in THE WIRE with mixed gas.
You can use ER70S-6 with 100% CO2 gas.
dong won oh
If you research past topics discussed on this forum, you'll find a lot of good information concerning welding on cast materials.
Basically, it all boils down to the fact that cast metals don't like to be welded and will crack out at the slightest provication.
They can be fused however, through many different ways.
The best method that I have found for weldments that are to large or impractical for stress relieving is to preheat as large of an area as possible, concentrate the preheat at the weld area on the cast to a dull red in color just before welding. Get your welding done as fast as possible and don't let the weldment cool off during the welding process. When finished welding, re-heat the entire area and either bury the whole thing in warm, dry sand, or wrap it as good as possible with insulating material such as K-wool or even fire-resistant fiberglass blanket. The idea is to let the weldment cool as slow as possible, thus preventing cracking. If your weld does'nt crack out within 72 hours after welding, it probably won't ever crack.
A lot of good welders that I know have been sucessful with this method, but most prefer to develop a way to bolt the pieces together rather than go through all the time and trouble to create a weld that may crack anyway.
There is a special electrode made for welding cast steel. I don't remember the designation off hand, but the brand name is CASTALLOY.
Good luck and let us know what works for you.
Are you refering to the carrier? Depending on the model my guess is that the material you are trying to weld is ductile nodular iron. I used to work for dana several years ago.
Thanks to all for the replies!
We are welding the axle tubes to the cast center section of the housing. These tubes are pressed into the center at the factory and plug welded in 3 places. For drag racing usage we need to weld the tubes to the center to keep them from shearing the plug welds and spinning in the casting. We also straighten bent housings for body shops and salvage yards. A lot of the times the tubes are loose in the casting once we get the housings straight so we have to weld those also.
I checked a Dana rear yesterday with a grinder and it seemed to indicate a casting (dull shorter spark). We are going to try welding it today with an MG250 electrode. Hopefully it works.
OK...picture clear now. The carriers you are talking about are made of ductile iron. I think the tube is a low/medium carbon steel. The plug welds are done at the factory using GMAW. After the tubes are pressed into the carrier, the plug welds are welded by hand. Gun is aimed down the center of the carrier plug holes and arc is started on the tube. Cant tell you volts or wire feeds. After striking arc, welders use a circular motion to pool the filler material in the carrier holes. Care is taken not to wash carrier material into the weld pool (you will get cracks if you do because of the high carbon content of the iron). Dont remember wire type that they use. if you want to put a bigger weld on than the factory plug welds you might seek knowledge regarding the joining to iron to steel and what is the best method to do this....maybe post and preheats as well as using a nickel wire.
good luck
Also....maybe a way to confirm that this is ductle iron is to use your nose. When you grind ductle iron it is oh so stanky (not a technical term). Has almost a rotten egg/ sulfur type smell.
