0.9mm, .035" 20 ga 1008 steel. Butt joint, fusion weld at top only, minimal surface prep. Cut perpendicular to weld seam. Shown through 5x microscope and raw camera capture. Small shiny things are really hard to take pictures of.
Power level: 66J
Not full penetration. Joint is homogenous. Very little heat discoloration on bottom
Power level: 100J
Full penetration. Has a slight stripe thru the joint. Bottom shows heat effect