Hydrogen embrittlement and MIG/ TIG welding - TTORA Forum
 
LinkBack Thread Tools Display Modes
post #1 of 1 (permalink) Old 06-03-2005, 09:19 PM Thread Starter
Veteran Member
 
Join Date: Dec 2004
Location: Kansas City MO
Posts: 1,712
Hydrogen embrittlement and MIG/ TIG welding

Here is an on line description of what I am talking about.


Eliminating Oxygen and Nitrogen at the weld start to reduce the possibility to weld porosity and excess weld spatter requires good shielding. In addition to Oxygen and Nitrogen the surrounding air contains Moisture or Water Vapor. The Water Vapor can also be drawn into the arc where it will disassociate into Oxygen and Hydrogen. Hydrogen can cause more than porosity problems. Some amount can dissolve in the molten steel and will only come out when the weld cools. Since they are very small, Hydrogen atoms it can migrate through the steel accumulating near defects, dislocations, etc. forming Hydrogen gas. This can cause cracking. These cracks may be in the weld itself or in the adjacent parent metal called the heat affected zone.

http://www.netwelding.com/improving_start_quality.htm

Well, where does the hydrogen embrittlement/ checking come from with MIG welding?

Using the same principles of inadequate inert gas flow to sweep away gasses that will react with the hot metal, you get the same effect in the area just behind where you welded. So as your welding along, the gas is directed exactly where your welding now but NOT where you just welded. The area you just welded is still very hot, hot enough to break apart the moisture in the air into hydrogen and oxygen which interacts with your weld, since there isn't any flux to prevent the hot metal from coming into contact like you do with stick welding you end up with some hydrogen checking/ embrittlement.

The reason why its a little less likely with TIG is that you go slower, but some metals especially the exotics need that post flow for a reason, to prevent hydrogen embrittlement!

Am I making any sense or still smoking crack?

Don't get me wrong, its most certainly possible to get hydrogen embrittlement with stick, you get some of it with 6010 because the cellulose flux has some moisture in it, and if you try to weld on sub freezing steel with 7018 you will most certainly get hydrogen embrittlement.

Anyways, not wanting to be arguemenative, just trying to express what I feel is usefull information.

Wally
WallyP226 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the TTORA Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome