ER4145 Filler rod and 319 Aluminum

By MACWelder Date 02-07-2008 17:38

First let me introduce myself. My name is Mark and I am currently working in a production shop with about 90% of production involving welding processes. I am almost done with my associates degree in welding technologies and plan to attend Ferris State University for my welding engineering degree. I am doing an internship for school where I work and one of my porjects is to research aluminum filler materials.

We are currently welding 319 aluminum sand castings using Alcotec ER4145. My employer wants me to find out if their is a cheaper alternative to our current filler rod. The process is GTAW using 1/8" tri-mix tungsten, 100% argon. We dont currently have any welding engineers or really anyone to set up welding processes so my company just goes off what our welding supply rep tells them which may not always be the most cost friendly.

I just wanted to know if anyone might have some ideas to a better alternative to our current filler rod.

Thanks again

By Lawrence (*****)

Date 02-07-2008 22:08

Hi Mark.. Welcome to the Forum.

The Aluminum Association publishes Welding Aluminum: Theory and Practice This is a pretty authoritative text and respected worldwide.

It's filler cross reference chart calls for 4145 as the filler of choice for 319 sand castings. With several footnotes, noting that 4043 may be used in some applications and that 4047 may also be used in some applications.

Now if 4145 is doing the job it might very well be penny wise and pound foolish to change fillers to a secondary choice. This time your vendor gave you good advice.

When the text notes that "some appliacations may use 4043 or 4047" the decision maker must look at exactly why a substitution would be made and what risks or benefits occur.

While 319 has excellent weldability.. Cracking can still be an issue... When all other preparation and process controls are being employed; Cracking is generally directly attributable to the amount of alloying incorperated into the filler.

By selecting 4043 you sacrifice almost 50% of the alloying Si, which again is the agent that has the greatest influence on hot cracking.

The other alternative, 4047, has a slightly higher Si percentage than the 4145 you are currently using and also likely is just as costly... But might be a good choice if cracking were a problem with the 4145

It breaks down like this

4043.......5.2% Si
4145......10% Si
4047......12% Si

In my opinion, the change your boss suggests is definatly an engineering level decision.