Perplexing Problem With 6061 T651 Alum

Date 03-24-2006 18:15

To All

I am having one hell of a time welding a 2" thick aluminum billet parts. These parts were manufactured out of a 4' X 6' sheet. The problem I am having is that there are pin holes in the weld bead. I ran some test beads on some diamond plate of the same material designation & produced no pin holes. Parts are SUPER CLEAN so contamination is not a factor. I checked all the standard stuff like gas connections, torch height control, different filler material diameters ect... Any ideas out there? Any Help would be appreciated.

Rod

By yorkiepap (***)

Date 03-25-2006 00:44

Hey Rod,
We weld a lot of 6061, but only to a thickness of 1". They are a casting so I preheat and they weld without any problem. I am guessing your diamond plate is much thinner and therefore no problems. Try preheating....just a guess......Denny

By rangerod (**)

Date 03-25-2006 04:10

Denny

I did preheat the 2" which is possible in billet form but once the part is machined preheat would warp it. I am thinking the checmical compositon is off some how, Thanks for the response. Its kind of a need to find out what is causing this due to the sensitive nature of the parts application.

Rod

By CWI555

Date 03-26-2006 01:51

Component Wt. %
Al 95.8 - 98.6
Cr 0.04 - 0.35
Cu 0.15 - 0.4
Fe Max 0.7

Component Wt. %
Mg 0.8 - 1.2
Mn Max 0.15
Other, each Max 0.05
Other, total Max 0.15

Component Wt. %
Si 0.4 - 0.8
Ti Max 0.15
Zn Max 0.25

105-106 vickers

This should be the ball park for your material.
As for Gasing, have you checked your gas for purity?

Is the diamond plate the same thickness?

What does your mtr say about the material?

Have you ran a sample of your base material?

If so, does the chemical breakdown match?

Does the hardness test match?

Given what you've stated, I think I'd be looking at the gas or the material.

Pin holes are not atypical for flaws when it comes to thicker parts. Though it is possible. LOF and others would seem to be on the more Atypical side.

Something else amiss that you haven't looked at I'd think, hope some of this helps.

In the past, many eons ago, I ran across a sim. problem. It was contaminated gas that turned out to be the problem in my case.

By rangerod (**)

Date 03-26-2006 02:25

The material supplier is looking the aluminum. I did not have time this week to change the gas to a different bottle. Our gas company delivery days are Mondays so I will have a new bottle delivered & check the results. I also ran beads on a 1" piece of 6061 T651 which resulted in pin holes without preheat & no pin holes with preheat. For the time being we'll have to wait until Monday to see if the gas is a factor in this problem. I'll have to check to see if we have any hardness testing equipment. I am fairly new at this company, less than a year, so I am still working out some of the kinks. Thanks for the help it is much appreciated.

Rod