Argon - Hydrogen Mixtures

Argon - hydrogen mixtures are employed in special cases, such as mechanised welding of light gauge stainless steel tubing, in which the hydrogen does not cause adverse metallurgical effects such as porosity and hydrogen induced cracking. By Increased  of welding speeds can be achieved in almost direct proportion to the amount of hydrogen added to argon because of the high  arc voltage. However, the amount of hydrogen that can be added varies with the metal thickness and type of joint for each particular application. Excessive hydrogen will cause porosity. Argon - hydrogen mixtures are limited to use on stainless steel, nickel - copper and nickel base alloys. The most commonly used argon - hydrogen mixture contains 15 % hydrogen which is used for mechanised welding of tight butt joints in stainless steel up to 0.062 in. (1.6 mm) thick. For manual welding,a hydrogen content of 5 % is sometimes preferred to obtain cleaner welds.