[Steveygreen3k]

Hi there, I am just wondering to what temp I would need to pre heat an EN32 steel shaft to ensure a crack free weld when I weld a drive flange to to that's plain mild steel, many thanks steveygreen3k

[weldin mike 27]

Hey mate,

I can't find anything that states that a preheat is required. Everything says that the weldability is good. In cases like this, a slight preheat of around 100 degrees and normal cooling usually surfice. However, a flange onto a shaft can sometimes crack because of expansion and contraction and that has nothing to do weldability.

[cj737]

Hey mate,

I can't find anything that states that a preheat is required. Everything says that the weldability is good. In cases like this, a slight preheat of around 100 degrees and normal cooling usually surfice. However, a flange onto a shaft can sometimes crack because of expansion and contraction and that has nothing to do weldability.

Depending on the shaft diameter, I’d think a controlled cooling is more productive

[weldin mike 27]

Why not do both?

[snoeproe]

Pre heating is a method of controlling the cooling rate. It helps slow down cooling.
Pre heating can also drive out hydrogen prior to welding and helps to minimize hardness spots in the haz which can cause under bead cracking in higher carbon steels.