By kenmui
Date 11-09-2002 01:16
Please clarify ....you state that you need to use 98 /2 ArCo2 . In reality, that gas blend is NOT a common blend
Typically for a mild steel spray arc transer with "hard wire" a 90/10 ArCo2 . Some proprietary trade name gases such as
Praxair's MIG Mix Gold is a 92/8 ArCo2
What is common though is a 98Ar / 2 O2 . Although there are some benifits(arc stability and wetting) of using this gas for
typical ER70S-3 ( 6... etc ) , the main purpose and use of this gas is for low alloy MIG wires such as the
ER80S-Ni1 , ER80S-D2 , ER90S-G ,ER100S-G etc.
The reason for this is as follows. A product which meets ER80S-D2 with a 90/10 ArCo2 will easily also meet ER90S-D2
with a 98Ar / 2 O2. There is obviously a significant increase in mechnaical properties(TS and YS ). Also very noticiable is that
with the addition of O2 , the Charpy VN ( impact properties ) , expecially with the low alloy Ni wires
Bottom line, if you are using a ER70S-6 ( -3 etc ) a 90/10 ArCo2 works very well for spray type transfer. Unless you
have a specialized ( automated for example ) application.
If your specs call for a 98 /2 make sure they are not refering to a Ar O2 blend. A 98 /2 ArCo2 is simply
not a popular mix . I checked the the cross ref chart and Praxair, Air Products
Air Liquide , AGA , MG and BOC all offer a 98Ar / 2 O2 , but only AGA has a standard 98 /2 ArCo2
I would guess the specs mean 98 Ar / 2 O2 if the electrode spec is ER80S or higher
I haven't dealt much with different mixtures but it was a good article in the AWS journal las month I thought.
