Hot roll and cold roll mild steel

[God mode restorations]

Evening all.
I have some 4mm hot rolled mild steel plate that I am making some shoots for my tarmac lorry. Also I got to make a couple of pivot brackets out of 5mm .the 5mm plate is cold rolled.i understand hot Rd is harder than the cold Rd. I will be mig welding the 5mm to the 4mm.is there any difference in welding the both together with one being harder material than the other..I that makes sense.

 

[scott0031]

They are slightly different grades but both mild steels. The bright should be En3 which is the weldable version of brights as a general mild steel. Mechanically it should be a bit stronger than the black but i would not call it harder in the mechanical sense. The term 'hard' used in Engineering is a materials resistance to being scratched and both of those materials are soft in hardness terms. For what you are doing weld it and forget it. Really no more complex than that.

 

[God mode restorations]

They are slightly different grades but both mild steels. The bright should be En3 which is the weldable version of brights as a general mild steel. Mechanically it should be a bit stronger than the black but i would not call it harder in the mechanical sense. The term 'hard' used in Engineering is a materials resistance to being scratched and both of those materials are soft in hardness terms. For what you are doing weld it and forget it. Really no more complex than that.

OK thanks for the information. ...