Welding mild steel to high strength steel

Hi All,

I have an application where I would like to weld mild steel to high strength steel.

Is there anything special I need to consider when welding the two steels together?

Thanks for reading.

MIG/TIG? What steels are being used? There may be a filler rod that is compatible with both materials being fused.

Would you be better off brazing the materials together, rather than welding?

For these sorts of questions, you may be better off directly contacting the suppliers of welding consumables to see what they recommend to be used, as using the incorrect technique/filler can lead to a much weaker weld and embrittlement of the base metals.

Hi Stephen,

I was planning on MIG welding as my TIG skills aren't up to scratch yet:(

The mild steel is a European standard cold rolled steel called DC01 (270-410MPa), which I think is similar to A1008. This is the new steel that I will be welding to the existing high strength steel. I don't have a name for the high strength steel but its tensile strength is 35-45Kgf/mm^2 (343-440MPa).

The filler material I have is ER70S-6.

I'd prefer to avoid using brazing this time around, but it could be a useful option for future projects!

A quick look at the filler materials specifications reads as it would be suitable, but it would be best to confirm, especially if you are welding onto structural components such as roll cages.

Stephen mentioned the heat affected zone, and the danger of the welding affecting the properties of the steel as it will effective be re-tempered at the weld.

As this is for a chassis, and IIRC, a load bearing suspension point, I'd suggest you do some double checking if the load paths are going to be affected, and whether annealing/normalising will be a good idea to reduce the possible brittle temper zone?

Hi lads,

If the risk is that the high strength steel becomes brittle during welding, could this be minimised or even prevented by TIG welding and tightly controlling the heat affected zone? Or is it simply impossible to avoid the welds becoming brittle!?