Burn through

Blaze659 · Fri Nov 07, 2014 6:02 pm

How much burn through would be enough to show good penetration / proper one pass heat? Should the backside just start showing signs of heat (ex small flat spots ) or 1/16 size mounds or more?

dsmabe · Fri Nov 07, 2014 6:19 pm

Whether it be alum or steel the backside should be, in my opinion, between half the width to the full width of the weld. Consistent all along the backside, no lumps or bare spots.
Steel shouldn't have any sugaring on the back.

Fri Nov 07, 2014 8:22 pm

Blaze659 wrote:How much burn through would be enough to show good penetration / proper one pass heat? Should the backside just start showing signs of heat (ex small flat spots ) or 1/16 size mounds or more?

What process, on what material?

It matters. Sanitary sch. 5 stainless will have a minimum of push-through. A sch. 80 2" open root carbon pipe test should have 1/16-1/8" internal reinforcement (a general rule... read the WPS).

This is a question with many different answers depending on the situation.

Steve S

Blaze659 · Fri Nov 07, 2014 9:02 pm

Could you give me some info on Mild Steel and Aluminum Tig welding? Is Mig and Stick the same? I mainly weld tubing and plate. I don't weld anything fancy yet!

What a WPS? Yip new guy!

Fri Nov 07, 2014 9:15 pm

Blaze659 wrote:Could you give me some info on Mild Steel and Aluminum Tig welding? Is Mig and Stick the same? I mainly weld tubing and plate. I don't weld anything fancy yet! What a WPS? Yip new guy!

Ah, I got it.

WPS= "Weld process specification". Every weld that's been designed by an engineer and qualified by a "competent weldor" will have a WPS that tells you what is and is not allowed. It will define (on stainless pipe, for example) the allowed root gap range, the allowed amount of land, the bevel, the filler material and thickness, and the allowed range of amperage. There can be many other variables for other materials, positions, purposes, what-have-you.

What, exactly, are you trying to weld at the moment? Give us a specific example, and you'll get a better answer.

Steve S

Blaze659 · Fri Nov 07, 2014 9:28 pm

First I really appreciate your help! I was Tig welding aluminum and steel flat bar making diffrent kinds of joints for practice. It looked like I was running good beads. I am just learning. Maybe 5 hours seat time. I welded an aluminum outside corner joint and was very happy with the look. Then I decided to pull the corner weld back against itself with just my hands and it broke the weld right down the middle. 1/8 thick aluminum. I posted pics of the weld and what happened and was told it was a cold weld. There was no deformity or sign on the inside of the corner weld to show good penetration so I figured for good penetration you should see something on the back side of welds to make sure you had good penetration. My steel lap joints showed a varying amount of deformity to the back. Anywhere from flat spots to 1/4 inch mounds. I really don't care for the mounds but I am not sure if just seeing the back start to change is good enough penetration. Hope this makes sense. I don't have pics right now. See "Expertise help needed" post in the TIG section for outside corner pics.