Hi. I know absolutely nothing about welding but need some advice. I thought that this forum would be a good place to get some. Am I wrong? Basically I need to identify what sort of weld has been done to my car, and how I can know if the quality is any good? My car had a sill (rocker panel) crushed and rather than replace the entire sill the insurance repairer cut out the damaged section and welded a new section in. I have never seen a weld that looks like this, nor the blue colour of what looks like oxidation or soot. It also looks like lots of heat has been used as smoke deposits cover the underside. From the pictures does anyone have any ideas what type of weld it is and why it looks like blue oxidation? The car is a 3 year old C4, so high strenghth steel is involved, or supposed to be. Thanks for any help.