Forge welding trouble with A36

[frglr_7bs]

I'm not sure if I should be posting my concern here but still hoping people will notice and offer their insights!

I'm a hobbyist blacksmith and I've had great luck with forge welding in the past so I thought I had it figured out. I've been working on a few different projects, mostly forge welding some Damascus billets and some general scrollwork. I've been using a coal forge, and the pieces always came out looking perfect, with no lines.

So my concern now is that this strange issue with the new lot of hot-rolled A36 I bought from a new supplier. I've had nothing but trouble since. The joints just won't stick, and when I do get a weld, it always seems to shear apart later. I've tried different temperatures, wire brushing, flux but nothing seems to work.

I've heard people mention that there can be slight variations in the composition of A36 steel from different suppliers. Is this a real thing? If so, what can I do to get this to stick? I've got a lot of it, and I don't want to just throw it away. Thanks for all your help!

 

[t_bone]

I'm not sure if I should be posting my concern here but still hoping people will notice and offer their insights!

I'm a hobbyist blacksmith and I've had great luck with forge welding in the past so I thought I had it figured out. I've been working on a few different projects, mostly forge welding some Damascus billets and some general scrollwork. I've been using a coal forge, and the pieces always came out looking perfect, with no lines.

So my concern now is that this strange issue with the new lot of hot-rolled A36 I bought from a new supplier. I've had nothing but trouble since. The joints just won't stick, and when I do get a weld, it always seems to shear apart later. I've tried different temperatures, wire brushing, flux but nothing seems to work.

I've heard people mention that there can be slight variations in the composition of A36 steel from different suppliers. Is this a real thing? If so, what can I do to get this to stick? I've got a lot of it, and I don't want to just throw it away. Thanks for all your help!

You need to get more aggressive with your process. Try using a high borax flux, and get the steel a little hotter than you normally would (like almost to the sparkling point) before you hammer it.
Also, make sure your surfaces are perfectly clean before you apply the flux

 

[Jackson55]

I'm not sure if I should be posting my concern here but still hoping people will notice and offer their insights!

I'm a hobbyist blacksmith and I've had great luck with forge welding in the past so I thought I had it figured out. I've been working on a few different projects, mostly forge welding some Damascus billets and some general scrollwork. I've been using a coal forge, and the pieces always came out looking perfect, with no lines.

So my concern now is that this strange issue with the new lot of hot-rolled A36 I bought from a new supplier. I've had nothing but trouble since. The joints just won't stick, and when I do get a weld, it always seems to shear apart later. I've tried different temperatures, wire brushing, flux but nothing seems to work.

I've heard people mention that there can be slight variations in the composition of A36 steel from different suppliers. Is this a real thing? If so, what can I do to get this to stick? I've got a lot of it, and I don't want to just throw it away. Thanks for all your help!

Yes, A36 composition varies widely! It meets strength specs, but the actual mix changes mill to mill.
Your new batch likely has higher silicon, which makes the scale stubborn and hard to remove, causing your welds to fail or shear.
I suggest that you stop brushing it. Before the first heat, use a grinder to strip all the mill scale off the surfaces.
You might also need a slightly higher, wetter heat than your old stock required like @t_bone also suggested.
Make sure your flux coat is generous and fully melts into the joint.

 

[Alan]

Also keep in mind that grain boundary contamination can be a problem. Some A36 batches have small amounts of stuff like sulfur or phosphorus that can mess with how well the weld sticks. Doing a test etch or spark test could show you if there's anything weird that you should watch out for.