Pearlitic C Clamps

No idea about the pearlitic thing but to weld steel to cast iron a stainless rod works wonders.

Ken.

"Rudolf Moehs" wrote in message news: snipped-for-privacy@nycmny-nntp-rdr-03-ge0.rdc-nyc.rr.com...

From an old university text book that I haven't opened for about 30 years, it appears that pearlite is a form of steel formed by slow cooling. It is more ductile and less brittle than martensite which is formed on quick cooling. I'd guess that it will weld OK, but pack some insulation around it after welding and let it cool slowly.

Tom

Hi Rudy,

It's a while since I studied any material science, but I'll have a go at answering. I've just been reading some of this up in my materials book, so if anyone spots a mistake in what I've said, please point it out. Pearlite is a natural composite of ferrite and iron carbide, which are two "phases" found in mixtures of iron and carbon which have been melted and then cooled. All steel and cast iron which has been cooled slowly from molten (i.e., not heat treated) will contain some pearlite. If a mixture of iron and carbon which contains 0.80% carbon by weight is cooled slowly, it will turn into pure pearlite. So if your clamps are pure pearlite they will contain 0.80% carbon, and someone here can probably provide advice on how easy they will be to weld. If your clamps aren't pure pearlite then the name doesn't really tell you anything useful about the steel.

Hope this helps.

Chris

From what I can tell if the clamps are pearlite then they are a relatively high carbon steel. When you weld them and the weld cools there will be some very brittle and hard martensite forming. I would preheat the pieces to at least 300 F then weld and cover with some sort of insulation to slow the cooling process. Pearlite refers to the grain structure. Pearlite forms when relatively high carbon steel ( 0.8 %) cools slowly such as when you anneal a steel. I found a listing of 125,000 to 150,000 psi tensile strength. 0.9 percent carbon steel is used for cold chisels and center punches so you can understand that the weld area will be very brittle if you cool the weld area too quickly. Using stainless welding rod as suggested reduces the chance of brittle fracture when cooling. The nickel and chromium are what helps. The parent material next to the weld that was not alloyed is still at risk. The best way is "belt and suspenders" Preheat, use stainless or ni-rod electrode and cool slowly. Randy

Thanks, Rudy

Are you sure you want to mig them. Other people seem to be reccomending stainless steel rod and I think these are only available for stick or tig.

I think Pearlite is cast iron that has been heated long enough for the graphite to separate out and form into either layers (like mother-of-pearl) or little balls. Usually it is called Malleable or Ductile iron. I've been told to use nickel or type 312 stainless for steel-to-whatever arc welds but they are expensive and hard to find as MIG wire.

jw

Thanks for all your responses, thank god for epoxy, since there won't be any load on the clamps except compression I think I'll just glue them in place.

thanks again, Rudy

I wouldn't use epoxy. I don't think it will hold up very well. If you aren't confident about welding them, you could make some kind of bracket which goes around the frame of the C-clamp and clamps it to whatever you're making. Granted, it's more work, but it'll be much stronger. If the clamps aren't under a high load you could consider drilling bolt holes in the frame of the clamp, but this isn't such a nice solution. What size are the clamps and what is the project?

Best wishes,

Chris

My guess is that they are pearlitic malleable iron or pearlitic ductile iron, neither of which is especially weldable. I never know of anyone promoting steel as being pearlitic because usually in a steel if more strength is desired a heat treat is done and the steel microstructure is made to be martensitic.

Cast irons can be welded but often people find the Heat Affected Zone (HAZ) to be objectionable because the carbon available from the graphite goes into solution and when the molten weld deposit cools rapidly due to the heat sink effect of the parts, ledeburite (iron carbide) will form which causes machinability problems and hard structures where cracks may initiate if used in tension.

Mark