Who can tell me about heat treatment of ansi 4130?
 

What types are available, infared, cryogenics etc, what properties do they give?

are you talking about before or after the tubes are made into a frame? either way, I don't know much. I can say with some certainty, if you head over to aircraftspruce.com, buy some 4130 tubes, TIG welded them into a bicycle frame, then you're good to go. the finished frame would not need to be heat treated.

I would think for anything to be 4130 grade of Chromoly that it would probably meet ANSI (American National Standards Institute)

What are you searching for? A little more detail in your question would be nice.

chromoly—an abbreviation for the steel alloy “chromium molybdenum.” Also abbreviated as chrome-moly, cromoly, or cromo. It is a combination of chromium (a highly corrosion resistant metal) and molybdenum (a high-quality, heavy metal), used in conjunction with carbon and iron to form a steel alloy. Chromium improves the alloy’s corrosion resistance; molybdenum counters the effects of “temper brittleness” during heat-treatment, as well as “weld decay” (a side-effect caused by the presence of carbon). Chromoly possesses excellent strength and modulus of elasticity, as well as being extremely versatile. It is also the most refined material being used in bicycle manufacturing, with over 100 years of use as a frame material. In mountain bikes it is used primarily in the construction of mid to high-end frames and components, although some manufacturers use one chromoly tube (usually the seat tube) in a high-tensile steel frame (see “high-tensile steel”) to give it a perceived edge over all high-tensile steel frames.

I just tried gas welding for the first time ever today on 4130 and its kind of tricky, but i guess its the kind of thing that takes practice.

I guess I'm looking for the ultimate heat treatment, something above and beyong the typical heat it up, cool it down stuff.

So are those seat tube only chromo builders putting a 4130 sticker on the seat tube for the purpose of misleading buyers into thinking the entire frame is chromo?

Heat treating is like any other structural process it's only the ultimate as relates to certain objectives. Try this link for data

http://www.suppliersonline.com/prope.../4130.asp#Spec

30 points is not normally heat treatable and yet this stuff apparently can be.

If you welded the frame up, then raised the temp to 1550, oil quenched the whole frame, then drew the temper to whatever level you wished, you would be fine. But if you braze it, it would not be happy with that treatment. If you heat treated the tubes you would loose the extra strength at the joints during assembly, and the joints are normally the points of greatest stress. With butted tubbing it works out nicely the fat walled parts are weakened during assembly but the paper thin less stressed areas retain the heat treatment. Assuming the raw tubes were HTd

If you brazed it, you may end up re-kitting at those temperatures. Also, heating and quenching a built frame , may leave you with a pretzel. Best to have each tube heat treated to your requirements (which can be different for each tube) or buy them pre treated and then low temperature braze (lugged w silver). this will have the minimal affect on changes tot he material property. BTW: this is all from engineering experience, not frame building experience.

Btw; saying something is "heat treated" is pretty much meaningless

I'm not recomending heat treating the whole frame and quenching it. Never heard of it done. I guess that wasn't clear.

I assume you are talking about stress relieveing the weld with heat treatment. According to Miller and Lincoln, if you TIG 4130 it is not necessary for aircraft building. If you gas weld it, an argument can be made for heat treatment stress relief although not everybody agrees. For a bicycle frame - I don't know. I'd just tig it and forget it! 4130 is awfully strong, and if welded correctly the weld is always more massive and stronger than the original tube.

A drawn tube has a grainular structure in the linear direction of the tube . A weld bead has totally random grainular structure (people can argue that ther eis no grainular structure), just like a casting, just like a brass fillet. A glob of weld bead is not necessarily "stronger" just because it is thicker. Please also consider 2 factors that will make the joint brittle. Too quick cooling and the wrong kinda weld rod AND hydrogent. The TIG process envelopes the molten metal in an inert gas, it prevents hydrogent from mixing in. Hydrogent will embrittle the joint and it will eventually crack and fail.

I thought welded joints were a weak point, even in CR. Like about 40% worth knocked off. Not to worry the material is massively strong.

welded joints done properly are very strong. properly = much skill & experience & correct selection of material & post weld treatment as required. Welding is great, just providing some useful insight. :)