Are foreign metals a welding issue?

When I was a youngster I would do some gas welding to replace rotted panels on my car. I got my sheet metal from old panels off other cars. At one time I used metal from an old English Ford (I think). Anyway, I found that you cannot weld unlike metals.
Is this an issue when welding frames on bikes that come from who knows where?

steel should be steel
its more likely an issue of the filler material (welding rods) being correct for the application or correct process

you need a particular rod to weld stainless to carbon steel 309L

there is no filler to put aluminum to steel with any kind of arc welding that i know of

most "steel" bike frames are 4130 chrome moly

im pretty sure the 4130 alloy is used because its needed to be able to make the steel into tubing

Silver flux coated brazing rods are da shnitz. Can braze stainless to steel if you like. Very strong stuff and flows like regular brass brazing rods.

What are the numbers on those rods and where can I get them???

Aluminum and steel differ in that there are ferrious and non ferrious metals. Ferrious are magnetic!!! Took a while for me to find the answer to that. They just don't mix well, even when moulten. Tin I believe is aluminum and steel, not sure of process to get them to bind?

Your flame on your gas set up has allot to do with the carbon content your welding. A more actylene rich flame will put more carbon into your steel.

FYI TIN
Tin - Wikipedia, the free encyclopedia

I have several wall mart bicycles that they claim are made of tensteel.
Or other Chinese cheap steel.
When they break I throw them away.

When I build a recumbent I want an old schwinn , for a donor frame.
The steel is American made from a time when that meant something.
I will find a schwinn ( at a yard sale) with rotted tires, rusty chain, bent rims, torn seat .
For the right one I ask "HOW MUCH."
Seventy Five Dollars they say.
I ll take it a say.
SHHHH !!! sometimes it is Five dollars. Not seventy five dollars.
TYhe local vender's don't understand why I will pay top dollar for some American made bicycles, and PASS on Wallmart junk.

__________________
Motorized bicyclist

Were you asking me?

If you were, you can buy silver flux coated brazing rods at most hardware stores or Home Depot. They are the ones with the blue flux on them.

The Schwinn Jaguar is a Chinese made bike. I've welded on them using both TIG and MIG. I've actually been impressed with the purity of the steel used in these bikes. If the steel is bad, or dirty, believe me, you'll know it when you try to use TIG. My experience is limited to the Schwinn bikes so I can't speak for the others. As for welding aluminum either with gas or electric, it is a process that requires some practice and not for the beginner. If the weld is at a structural point, let a professional do it unless you have mastered the art of aluminum welding.
Tom

__________________
Age and Treachery Will Always Triumph
Over Youth and Skill

You can weld aluminum with gas? Did you mean oxyacetylene or electric w/ gas atmosphere?

Maxvision,
Yes you can weld aluminum with oxy-acet. They did it long before heli-arc was around and I've seen some beautiful work done by people who know the process. As I said before, it's an art and takes practice to be proficient.
Tom

__________________
Age and Treachery Will Always Triumph
Over Youth and Skill