Why Carbon and Stainless Steel Wire shouldn’t be used together for Welding?

welding

Stainless Steel Forgings and Carbon steel forging both have their own place in the world of mechanical usages and while a  pure stainless steel build might be cost inefficient, costs can be cut by welding it Carbon to reduces costs. Such a weld may not be unique but it poses its own unique set of challenges.

MIG welding is used instead of resistance welding due to the fact that stainless steel and carbon steel have different electrical conductance. Thus reaching the optimal temperature for the right weld is fairly difficult. When resistance welding is made use of Carbon steel has to be preheated due to the fact that it is more electrically conductive and doesn’t acquire the same temperature as its counterpart as quickly.

Below are the reasons why you would want to avoid welding these two types of steels together:

1.Difficulty-

Welding dissimilar metals only adds to the woe of the welder which also translates to higher costs, labour and error. Any economically sound venture would avoid the aforementioned things.

2.Hot cracking –

Stainless steel is much more electrically resistant than carbon steel, this means stainless steel heats up much faster than its counterpart carbon steel. Thus, stainless steel takes less time to reach weld temperatures as compared to carbon steel. SO while stainless steels wait for carbon steel to reach its weld temperature it can overheat and crack thus introducing errors in the weld. Filler based welding like MIG welding can be used as a get around this problem but it is far from perfect.

3.Thermal Expansion at high temperatures –

Welding similar metals also poses another problem that is heat affects stainless steel and carbon steel differently. This means that both the metals have different expansion rates which can cause extra fatigue in the welded joint. This extra fatigue lessens the integrity and life of the weld.

4.Increased Bimetallic Corrosion –

Stainless steel has a unique property of being rust free due to the formation of oxide layer when it is exposed to corrosion. But when an uncovered weld of Stainless steel and plain carbon is exposed to highly alkaline conditions like that of saltwater can corrode the weld. This is due to the fact that intermixing of plain steel and stainless steel compromises the anti-corrosive property of stainless steel and allows the rust to form.

5.Reduced strength –

Joining to not so similar things may not always cover each other’s weaknesses rather it may highlight them. This is what exactly happens with welding of stainless steel and carbon steel. Even if we use filler based welding methods it isn’t a guarantee we would get a strong joint. The difference in operational tolerance and weld temperatures can wreak havoc if left unchecked.