good weld penetration, suitable for thicker plates and steel significantly covered with mill scale. Suitable for short circuit, globular, pulse and spray transfer welding. Maximum productivity for thin metals in short-circuiting mode; has lower tendency to burn through than higher-CO2 mixes and has suitably high deposition rates. C-10 (90% argon/10% CO2) is common in production environment. Has low spatter and good weld penetration, though lower than C-15; suitable for many steels. Same applications as 85/15 mix. Sufficient for ferritic stainless steels. C-5 (95% argon/5% CO2) is used for pulse spray transfer and short-circuiting of low alloy steel. Has better tolerance for mill scale and better puddle control than argon-oxygen, though less than C-10. Less heat than C-10. Sufficient for ferritic stainless steels. Similar performance to argon with 1% oxygen. O-5 (95% argon/5% oxygen) is the most common gas for general carbon steel welding. Higher oxygen content allows higher speed of welding. More than 5% oxygen makes the shielding gas oxidize the electrode, which can lead to porosity in the deposit if the electrode does not contain sufficient deoxidizers. O-2 (98% argon/2% oxygen) is used for spray arc on stainless steel, carbon steels, and low alloy steels. Better wetting than O-1. Weld is darker and more oxidized than with O-1. The addition of 2% oxygen encourages spray transfer, which is critical for spray-arc and pulsed spray-arc GMAW. O-1 (99% argon/1% oxygen) is used for stainless steels. Oxygen stabilizes the arc. Argon-helium A-25 (25% argon/75% helium) is used for nonferrous base when higher heat input and good weld appearance are needed. A-50 (50% argon/50% helium) is used for nonferrous metals thinner than 0.75 inch for high-speed mechanized welding. A-75 (75% argon/25% helium) is used for mechanized welding of thick aluminium. Reduces weld porosity in copper. Argon-hydrogen H-2 (98% argon/2% hydrogen) H-5 (95% argon/5% hydrogen) H-10 (80% argon/20% hydrogen) H-35 (65% argon/35% hydrogen) Others Argon with 25–35% helium and 1–2% CO2 provides high productivity and good welds on austenitic stainless steels. Can be used for joining stainless steel to carbon steel. Argon-CO2 with 1–2% hydrogen provides a reducing atmosphere that lowers amount of oxide on the weld surface, improves wetting and penetration. Good for austenitic stainless steels. Argon with 2–5% nitrogen and 2–5% CO2 in short-circuiting yields good weld shape and color and increases welding speed. For spray and pulsed spray transfer it is nearly equivalent to other mixes. When joining stainless to