Why does mild steel refuse to stick when I’m forge welding?

[Breylen]

I’ve spent more than a few sweaty sessions hammering bars together, only to have them stubbornly not fuse.

What do you think is the culprit behind those inconsistent welds? Is it the heat, the flux, the technique, or just some really stubborn steel?

 

[Ohio Rusty]

Start with as clean metal as you can make it in those forge welding scarfs. I like Iron Mountain flux with the small metal bits infused with the flux powder. Try to get the metal to a yellow heat, just starting to sparkle then put your scarfs together and lightly tap a couple of times to start the stick together, more flux and back into the fire for another yellow heat and a forge weld this time. I haven't always been successful either with forge welds sometimes.

 

[Dociron]

Learning to forge weld is something that is based on knowing all the principals of the process VERY well.

To answer your question it would help to know what type of forge you are using? When I started smithing over fifty years ago it was thought that you couldn't weld in a gas forge. Why ? Because most of the gas forges at the time were incapable of producing a neutral or almost neutral atmosphere. Too much oxygen creates excessive scale which inhibits welding

In solid fuel forges we have complete control of the atmosphere but it requires constant monitoring.

This means keeping a deep bed of coals under the pieces to be welded. This can't be done in a shallow fire pot you need a MINIMUM of 3" under your work at all times through the complete welding heat cycle. This will consume most of the oxygen before it reaches the metal.

At the same time it is just as important to keep the TOP of the fire closed. Too often I see people leaving the top of the fire open saying it's the only way they can see the materials temperature WRONG. Material heating on the top of a bed of hot coals is exposed to all the oxygen that's in the air in the shop and is just as detrimental in producing scale as letting it in from the bottom.

So good fire management is KEY. Good depth of coal under your work , banked around the sides and clean coke in the center and the top of the fire. A light poker can be used to lift coke periodically at the top of the fire to see your heat.

Heating is important to. Bring the work to welding heat at a reasonably slow rate. The steel has to be heated ALL the way through not just on the surface. Larger work like 3/4" or more should be brought to a good orange heat and aloud to soak for a minute or two before bringing to full welding heat.

Judging welding heat is the next critical step. With mild steel a good welding heat is just BEFORE you start to see sparks. The surface of the metal should look wet and be very bright yellow. A few sparks are expectable but once you see a large volume of sparks your burning the metal and it may not weld then either!

An aid to learning the proper heat can be made from a piece 1/4" round stock. Forge a VERY sharp point on the end of this 18" or so long rod. When you think you have reached welding heat reach into the fire with the pointed end and touch the piece to be welded. If your work is at welding it will stick to it. Be sure the point is very thin so you can pull it off.

As far as flux goes any of the commercial fluxes should work well. I personally don't like borax because it doesn't really do much cleaning. It only provides a glassy covering and is slippery when trying to put two pieces together. Apply your flux just before you reach an orange heat about 1400 deg. before the scale starts to form.

Hope this helps!

 

[FPDoc]

Learning to forge weld is something that is based on knowing all the principals of the process VERY well.

To answer your question it would help to know what type of forge you are using? When I started smithing over fifty years ago it was thought that you couldn't weld in a gas forge. Why ? Because most of the gas forges at the time were incapable of producing a neutral or almost neutral atmosphere. Too much oxygen creates excessive scale which inhibits welding

In solid fuel forges we have complete control of the atmosphere but it requires constant monitoring.

This means keeping a deep bed of coals under the pieces to be welded. This can't be done in a shallow fire pot you need a MINIMUM of 3" under your work at all times through the complete welding heat cycle. This will consume most of the oxygen before it reaches the metal.

At the same time it is just as important to keep the TOP of the fire closed. Too often I see people leaving the top of the fire open saying it's the only way they can see the materials temperature WRONG. Material heating on the top of a bed of hot coals is exposed to all the oxygen that's in the air in the shop and is just as detrimental in producing scale as letting it in from the bottom.

So good fire management is KEY. Good depth of coal under your work , banked around the sides and clean coke in the center and the top of the fire. A light poker can be used to lift coke periodically at the top of the fire to see your heat.

Heating is important to. Bring the work to welding heat at a reasonably slow rate. The steel has to be heated ALL the way through not just on the surface. Larger work like 3/4" or more should be brought to a good orange heat and aloud to soak for a minute or two before bringing to full welding heat.

Judging welding heat is the next critical step. With mild steel a good welding heat is just BEFORE you start to see sparks. The surface of the metal should look wet and be very bright yellow. A few sparks are expectable but once you see a large volume of sparks your burning the metal and it may not weld then either!

An aid to learning the proper heat can be made from a piece 1/4" round stock. Forge a VERY sharp point on the end of this 18" or so long rod. When you think you have reached welding heat reach into the fire with the pointed end and touch the piece to be welded. If your work is at welding it will stick to it. Be sure the point is very thin so you can pull it off.

As far as flux goes any of the commercial fluxes should work well. I personally don't like borax because it doesn't really do much cleaning. It only provides a glassy covering and is slippery when trying to put two pieces together. Apply your flux just before you reach an orange heat about 1400 deg. before the scale starts to form.

Hope this helps!

Good post! I've been smithing 50+ yrs as well and you share a bunch of good and helpful hints. I started by making chain (controlled joins, easy scarfs and a LOT of repitition) also you learn a lot about time and material management re: irons in the fire... I only used plain borax since I had nothing else (can use "blow sand".. if you must) and you have to have to follow the plan you've layed out.. it's all about seeing what you're looking at and understanding what you need to do. Again, this is a treasure trove of hard earned hints and tips.. You guys are so lucky to get this in one quick read.. if you take it to heart.

 

[Breylen]

Start with as clean metal as you can make it in those forge welding scarfs. I like Iron Mountain flux with the small metal bits infused with the flux powder. Try to get the metal to a yellow heat, just starting to sparkle then put your scarfs together and lightly tap a couple of times to start the stick together, more flux and back into the fire for another yellow heat and a forge weld this time. I haven't always been successful either with forge welds sometimes.

Cool advice. I dig the step-by-step way, esp starting with clean metal and tapping lightly at first, before welding all the way

 

[Alan]

Good post! I've been smithing 50+ yrs as well and you share a bunch of good and helpful hints. I started by making chain (controlled joins, easy scarfs and a LOT of repitition) also you learn a lot about time and material management re: irons in the fire... I only used plain borax since I had nothing else (can use "blow sand".. if you must) and you have to have to follow the plan you've layed out.. it's all about seeing what you're looking at and understanding what you need to do. Again, this is a treasure trove of hard earned hints and tips.. You guys are so lucky to get this in one quick read.. if you take it to heart.

Thanks so much for sharing your experience. Your insights on chain-making and managing time are invaluable, and it’s wonderful to hear how much you’ve grown in your craft over the years. This is a fantastic resource for anyone interested in getting into smithing.

 

[Alan]

Learning to forge weld is something that is based on knowing all the principals of the process VERY well.

To answer your question it would help to know what type of forge you are using? When I started smithing over fifty years ago it was thought that you couldn't weld in a gas forge. Why ? Because most of the gas forges at the time were incapable of producing a neutral or almost neutral atmosphere. Too much oxygen creates excessive scale which inhibits welding

In solid fuel forges we have complete control of the atmosphere but it requires constant monitoring.

This means keeping a deep bed of coals under the pieces to be welded. This can't be done in a shallow fire pot you need a MINIMUM of 3" under your work at all times through the complete welding heat cycle. This will consume most of the oxygen before it reaches the metal.

At the same time it is just as important to keep the TOP of the fire closed. Too often I see people leaving the top of the fire open saying it's the only way they can see the materials temperature WRONG. Material heating on the top of a bed of hot coals is exposed to all the oxygen that's in the air in the shop and is just as detrimental in producing scale as letting it in from the bottom.

So good fire management is KEY. Good depth of coal under your work , banked around the sides and clean coke in the center and the top of the fire. A light poker can be used to lift coke periodically at the top of the fire to see your heat.

Heating is important to. Bring the work to welding heat at a reasonably slow rate. The steel has to be heated ALL the way through not just on the surface. Larger work like 3/4" or more should be brought to a good orange heat and aloud to soak for a minute or two before bringing to full welding heat.

Judging welding heat is the next critical step. With mild steel a good welding heat is just BEFORE you start to see sparks. The surface of the metal should look wet and be very bright yellow. A few sparks are expectable but once you see a large volume of sparks your burning the metal and it may not weld then either!

An aid to learning the proper heat can be made from a piece 1/4" round stock. Forge a VERY sharp point on the end of this 18" or so long rod. When you think you have reached welding heat reach into the fire with the pointed end and touch the piece to be welded. If your work is at welding it will stick to it. Be sure the point is very thin so you can pull it off.

As far as flux goes any of the commercial fluxes should work well. I personally don't like borax because it doesn't really do much cleaning. It only provides a glassy covering and is slippery when trying to put two pieces together. Apply your flux just before you reach an orange heat about 1400 deg. before the scale starts to form.

Hope this helps!

Thanks for the clear tips. Fire depth, oxygen control, and heat cues make forge welding feel much more doable, even on tricky pieces.