Soldering Hot rolled mild steel

[nigel jones 5Participant @nigeljones5]

[nigel jones 5Participant @nigeljones5]

I need to SS 4 pieces of hot rolled 6mm sheet together. Since the steel has an oxidisation coating on it I guess its not a good idea to solder straight to it. Removing it seems near impossible – any ideas?

[Ian S CParticipant @iansc]

fizzy,unless you want to take it off with emery cloth, or file it, you can use either the electrolytic rust removal system, or soak it for a day or so in citric acid, or similar. Although I find that brazing with Oxy A, or propane, with a neutral flame you don't need much of a clean up at all. Ian S C

[colin hawesParticipant @colinhawes85982]

I usually clean up the surface with an angle grinder. Colin

[Gordon WParticipant @gordonw]

Angle grinder with wire brush- must wear goggles. Acid flux, Bakers , solder will stick to all the cleaned bits no problem.

[Ian S CParticipant @iansc]

Not Bakers, acid, fizzy want to silver solder, so an appropriate flux, or as I usually do borax. Ian S C

[Gordon WParticipant @gordonw]

Sorry, I read SS as soft solder. For some reason I assumed he was soldering the sheets together prior to machining.

[Ian S CParticipant @iansc]

Gordon, you could be right, fizzy can take the one that suits. Brazing little bits of steel, I use scrap sheet brass cut into strips about 5 mm wide, and borax for flux, works ok for me. Ian S C

[HomeUseParticipant @homeuse]

Try dilute Hydrochldoric acid (Brick cleaner) to clean steel sheet – wash off with clean water and coat joint area with Borax paste – clamp in position and heat to just under cherry red and apply Silver Solder to edges of joints – solder will flow towards flame/heat position (Capillary action) – let cool normally – DO NOT COOL IN WATER – causes brittal joint

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