Mild steel weldability?

[dobbslc]

I need to weld some machined steel bar to some ERW tubing, bar will be about 22mm diameter with a drilling through it and the tube 20mm dia by 2mm wall, the question is what kind of steel bar do i need?
I was going to use some en1a but have read it's not suitable to welding, I don't want it cracking as it is for a seat sub frame on my bike.....
I've got odds and ends of bar in the garage but don't remember what's what so will need some new stuff so I know what grade I've got.
Thanks.

 

[Mr shiney]

If memory serves me right EN3 will be fine. EN1 has lead in it to make it better to cut but makes it horrible to weld.

 

[Chris Stevens]

Never a good idea to weld thick to thin, and it would be better if you can replace bar with tube.

 

[dobbslc]

It's for mounting the sub frame to the main frame so I need a "plug" to insert into the end of the tubing that has a hole in it for an 8mm bolt. I'll machine down the end of the plug so it sits inside the end of the tube then drill two small holes to weld into then run another weld around the joint. I hope that makes sense...
I just realized that I have to be careful what types of metal I'm welding together.

 

[Chris Stevens]

Best possible way of fitting part like that is to machine a register so slug fits inside tube, and silver solder or braze it. Alternatively drill holes in the tube part and plug weld it. Strength depends of fit of the slug into the tube, and if you do weld it the filler material isnt critical.

 

[Brad93]

Stay well clear of EN1

 

[dan.taylor.1]

How long does the tube need to be? Could you not bore the bar and make it in one?

 

[dobbslc]

Chris yes plug weld it, that's what I'm going to do I couldn't think what to call it.
The tube is going to be about 1m long bent into a loop possible with a kick up in it so I can't bore it really.
I've also done a bit if googling and found that en1 is for finished machining work and not good for welding!
I've ordered a piece of 25mm en3 bar to work with now
Any more tips for this kind of joint?
I'm going to tig weld it after some more practice, lots more practice!....

 

[Chris Stevens]

If you are using ERW tube, you might have problems with cracking when bent if its very thin, so stick with thicker then you wont have any problems at all. If you have oxy-acetylene access it would be better to braze your joint, but if not I would suggest plug welding using MIG (no real need for TIG).