Cracking centerline Excessive dilution Add more filler metal or use technique to achieve slightly convex weldbead. Check dissimiliar joining chart to make sure correct filler material is being used.
Cracking Random Overstressed weld Lower amperage or voltage or increase travel speed to lower heat input, which causes distortion. Use step welding technique, change joint design. Keep the interpass temperature below 150°C (300°F).
Cracking HAZ Usually base metal related Ensure not welding with machinable grade of material containing high levels of low melting intermetallics.
Porosity Poor gas shielding, moisture, presence of excessive lubricant Correct shielding gas selection, gas cup size, gas flow rate. Clean off lubricant. Use ceramic backup tape without foil as glue used can sometimes cause porosity.
Excessive Spatter Incorrect parameter settings or wire composition. Inconsistent cast and helix in MIG wire Lower wire feed speed or increase voltage. Correct shielding gas selection, Look for source of moisture. Use wire with cast and helix control or remove wire straightener on wire feeder.
Lack of Fusion Joint design, too much filler metal, or excessive oxide buildup between passes Open up weld joint by increasing bevel angle. Decrease filler metal rate by lowering wire feed speed or increase travel speed. Increase voltage to increase fusion rate into base metal. Decrease travel speed to facilitate proper fusion into weld joint. Nickel alloys may require grinding between some or all passes to remove high melting nickel oxides.
Rust Insufficient Post Weld Cleaning, joint preparation using plasma, fixturing All welds require post weld cleaning. Ensure no iron contamination from post weld cleaning technique. Proper post weld cleaning. Finish grind plasma cut joints to remove contamination by nitrogen. Avoid using contaminated or carbon steel fixturing, tooling, or hoists.
Distortion Overheating weldment Lower heat input, use more frequent tacks, improve fixturing.
Undercut Wrong welding speed, poor weld puddle flow, incorrect grounding, base metal chemistry Slow travel speed, use filler metal with microelement control, split grounds.
Arc Blow Incorrect grounding Split grounds, check ground connections.
Slag Inclusions Welding technique Use a welding technique that facilitates slag which flows towards the puddle.