WELDING AR235 PLATE

[Steelforbrains]

I am attempting to construct a liner consisting of AR235 plate to line the the inside of a trommel conveyor that my company is building. For those that don't know a trommel conveyor is basically a large steel cylinder that is used to sort materials. The trommel is mounted on an incline and rotated and the material passing through is separated through holes of varying size. Our trommel is about 7 ft in diameter and 40 ft long and is used to sort scrap metal (mainly shredded cars). Anyway back to my question. I need to weld a large cylinder of 3/8" AR235 plate to the inside of the infeed section of my trommel which is A36 steel. I plan on MIG welding this construction and would like to know what type of wire/gas combination is recommended? The welds in this construction will be subjected to both impact and wear from the loading of the materials. Any help would be appreciated.
Thanks

 

[metengr]

I would recommend using an SFA 5.18 ER70S-3 filler metal for joining the AR235 liner to the A36 base material. The shielding gas should be SFA 5.32 SG-C (CO2).

For the stated base metal thicknesses, I would use a 200 deg F preheat.

 

[GRoberts]

I normally think metengr's advice is spot on, but think that the 100% CO2 shielding gas mentioned is less than optimum. Since you are welding thick material, for GMAW, you would want to weld in spray transfer mode. This runs best with at least 80% argon when mixed with CO2. Popular spray mixes are 90%Ar/10%CO2, 95%Ar/5% CO2, or 98%Ar/2%O2. Straight CO2 will give you either short-circuit transfer which promotes lack of fusion on thick materials like this, or globular transfer which is messy and undesirable.

You really have several options with regards to filler metal though. Carbon steel, as metengr mentioned, will have good impact toughness, but will not be that hard. Austinitic stainless such as ER309L will be even tougher, and a little softer, but tends to work harden, and will not contribute to hydogen cracking as carbon steel welding will in the right circumstances. Nickel based fillers such as ERNiCr-3 will also work well, but are expensive. They will be both hard and tough compared to the other options, and will not contribute to hydrogen cracking either. The stainless wire can be run on 98%AR/2%O2 or 95%Ar/5%CO2 since you aren't really worried about carbon pickup, and the Nickel typically uses 100% Ar, or Ar with He mixed in if a hotter arc is desired.

 

[metengr]

After reviewing the post by GRoberts, I would tend to agree that for 3/8" plate thickness you would increase the chances of LOF with short circuit transfer - although I have seen some experienced MIG welders handle this with minimal problems.

The bottom line is to go with a more conservative spray-arc transfer mode as Groberts mentions.

The AR235 is a lower end abrasion resistant plate that is really a 0.45% carbon steel with no special heat treatment requirements. The only specification is a surface hardness of 235 BHN. Regarding filler metals, I looked at similar options and given the use of a lower end abrasion resistant plate, for the cost and application, it seemed like carbon steel filler metal was the better alternative.

 

[Steelforbrains]

Thank you for all of your help, I think that we will just use the carbon steel filler wire. I will have to check to see what gases we have in stock to determine what we will use. I'm not sure if this will affect your recommendations but the AR235 plate will be welded to 3/4" A36 steel with a 5/16" fillet.