Quote Originally Posted by jerky View Post
when your welding stainless you should always use filler. even if you dont need to. the reason being that when you weld stainless, you creat alot of heat in one area, and being stainless, it doesent move that heat very good. SO in your HAZ (heat affected zone) becasue you have such high heats, you can get carbide percipitaion. basically the worse thing to have on stainless. ADDING filler whilst you weld actually decreases the weld puddle temperature thus reducing the chance of CP.
Yeah thanks ! I read that feeding wire in helps the temperature stay down a lot when welding stainless. This time was mainly a practice attempt. I am still really slow and cant get good body position to move fluidly. I have a small spool of left over 308L stainless weld wire (or something) from a mig welder I am going to feed that stuff into the weld next time. I read somewhere that the silica in it or something helps keep it cooler. I just need tons more seat time to practice feeding wire and moving. Its also hard since the pipes a curved thing and not flat it makes it harder. Ill keep trying though.

I am not sure about Carbon Precipitation but I read this.

http://www.azom.com/article.aspx?ArticleID=1177

Yeah looks like elevated temperatures will allow the chromium to form carbides when the temperature is elevated. Ruining the corrosion resistance and making it brittle. This stuff makes sense since I have taking a material science class on grain boundry formation after elevated temperature and this makes perfect sense. When the grain boundaries reform the chromium and the carbon from carbides on the surface.

Doesn't solar flux prevent this? I see much less black chunky stuff inside the pipe in comparison to when I welded with out it.

Do you know what temperature the weld would be with out filler and with filler? Looks like the range is like 425 - 800 C with 700 C being a critical temperature. I guess Ill get a pyrometer to measure it with and with out filler. Ill have to test it I guess.