Need to Braze or Solder Brass to some 304 Stainless, any Tips or Advice

[emag]

Anyone have any experience with soldering or brazing stainless steel?

I need to attach a brass plumbing fitting to a 304 stainless steel valve. It's not going to be under very much stress or high pressure. Should I solder it or braze it? I'm a pro at soldering copper plumbing, but have never brazed anything or even seen it done.

If you think you could help me out, let me know and I'll ask some more detailed questions.

Thanks

[Alamo]

I have done alot of soldering on random projects over the years and some plumbing with basic copper pipe. Now my knowledge only knew it as soldering but from reading the wiki on brazing tells me its just soldering. Put your flux like you would glue on pipes, on the inside on the outer pipe and the outer on the inner pipe "hope not confused hehe." Heat the pipe up with your white-gas or whichever type of torch you have and when the copper really starts to heat up to when you apply the solder it melts not because of torch but from the heat of the pipe.

When applying the solder make sure to get a decent amount around the connecting point because what happens is a pressure "shenanigans" goes on and pulls the solder into the area between the two pipes, sealing them together.

Now sometimes the torch can't get the pipe hot enough so the solder just doesn't seem to melt and this can also cause the solder just go on the outside of the pipe and just cover the seal which can have holes and leak ect... just don't do it shitty if your going to do it heh, not like its hard to fix if you do you can just heat it back up and the solder will melt away if you apply the torch back to it directly. There is also bristle pads you can get at hardware stores that you can just wipe when the solder is hot and it will take it all away which helps more so if your in a circuit board setting but yeah!!

So

1. Apply flux to pipe
2. Fit pipes together and heat
3. Apply a bit of flux/solder see if melts on pipe
4. Apply good amount of solder around the opening to were it starts to seam like it spreads and builds up a little bump layer
5. Test and fix accordingly.

Also with the gas, pull away the flame when you apply the solder to make sure its actually the pipe and not the flame. Good Luck :D

[ytter_man]

The brass will get red or orange hot before the stainless (or vice versa... cant remember) so take this into account while using solder, because it will flow towards heat and flux.

Also, those "shenanigans" that cause solder to flow is called "capillary action" IIRC.

[Alamo]

Hrmm this is true I totally ignored the stainless steel part /sigh

INFORMATION

Welding Dissimilar Metals

Welding together of different metals, such as of Grade 304 to Grade 430 or a stainless steel to a mild steel, can be carried out, although some extra precautions need to be taken. It is usually recommended that over-alloyed austenitic welding rods, such as Grade 309, be used to minimise dilution effects on the stainless steel component. The composition of the weld deposit resulting from dissimilar grade welding is shown in the Schaeffler diagram or its successors by De Long and more recently the WRC. AS 1554.6 contains a table giving the pre-qualified consumables for each combination of dissimilar metal welds

Soft Soldering

All grades of stainless steel can be soldered with lead-tin soft solder. Leaded solders should not be used when the product being soldered is used for food processing, serving or transport. Soldered joints are relatively weak compared to the strength of the steel, so this method should not be used where the mechanical strength is dependent upon the soldered joint. Strength can be added if the edges are first lock-seamed, spot welded or riveted. In general welding is always preferable to soldering.

Recommended Procedure for Soldering

Recommended procedure for soldering:

· 1. The steel surfaces must be clean and free of oxidation.

· 2. A rough surface improves adherence of the solder, so roughening with grinding wheel, file or coarse abrasive paper is recommended.

· 3. Use a phosphoric acid based flux. Hydrochloric acid based fluxes require neutralising after soldering as any remnant traces will be highly corrosive to the steel. Hydrochloric acid based fluxes are not recommended for soldering of stainless steels.

· 4. Flux should be applied with a brush, to only the area being soldered.

· 5. A large, hot iron is recommended. Use the same temperature as for carbon steel, but a longer time will be required because of stainless steel's low thermal conductivity.

· 6. Any type of solder can be used, but at least 50% tin is recommended. Solder with 60-70% tin and 30-40% lead has a better colour match and greater strength.

Brazing (Silver Soldering)

When welding is impractical and a stronger joint than soft soldering is required, brazing may be employed. This method is particularly useful for joining copper, bronze, nickel and other non-ferrous metals to stainless steel. The corrosion resistance of the joint will be somewhat lower than that of the stainless steel, but in normal atmospheric and mildly corrosive conditions brazed joints are satisfactory. Because most brazing operations involve temperatures at which carbide precipitation (sensitisation) can occur in the austenitic grades, low carbon or stabilised grades (304L, 316L or 321) should be used. Ferritic grades such as 430 and 3CR12 can be quenched from the brazing temperatures, but hardenable martensitic grades (410, 420, 431) should not be heated above 760°C when brazing. The free machining grades 303, 416 and 430F should generally not be used as a dark scum forms on the surface when fluxing and heating, which adversely affects the appearance of the steel.

Recommended Procedure for Brazing

Recommended procedure for brazing:

· 1. Use silver brazing alloys with melting points from 590-870°C. Select the alloy for best colour match.

· 2. Remove dirt and oxides from the steel surfaces and apply flux immediately.

· 3. A slightly reducing flame should be played across the joint to heat uniformly.

· 4. For high production work use induction heating or controlled atmosphere furnaces (argon, helium or dissociated ammonia with dew point of about -50°C).

· 5. After brazing remove all remaining flux with high pressure steam or hot water.

· 6. When brazing grade 430 use a silver solder with 3% nickel. This alloy also helps to minimise crevice corrosion when used with austenitic grades.

[emag]

Hrmm this is true I totally ignored the stainless steel part /sighAs well as the part of my op where I said that I'm a pro at soldering copper plumbing.

INFORMATION

Welding Dissimilar Metals

Welding together of different metals, such as of Grade 304 to Grade 430 or a stainless steel to a mild steel, can be carried out, although some extra precautions need to be taken. It is usually recommended that over-alloyed austenitic welding rods, such as Grade 309, be used to minimise dilution effects on the stainless steel component. The composition of the weld deposit resulting from dissimilar grade welding is shown in the Schaeffler diagram or its successors by De Long and more recently the WRC. AS 1554.6 contains a table giving the pre-qualified consumables for each combination of dissimilar metal welds

Soft Soldering

All grades of stainless steel can be soldered with lead-tin soft solder. Leaded solders should not be used when the product being soldered is used for food processing, serving or transport. Soldered joints are relatively weak compared to the strength of the steel, so this method should not be used where the mechanical strength is dependent upon the soldered joint. Strength can be added if the edges are first lock-seamed, spot welded or riveted. In general welding is always preferable to soldering.

Recommended Procedure for Soldering

Recommended procedure for soldering:

· 1. The steel surfaces must be clean and free of oxidation.

· 2. A rough surface improves adherence of the solder, so roughening with grinding wheel, file or coarse abrasive paper is recommended.

· 3. Use a phosphoric acid based flux. Hydrochloric acid based fluxes require neutralising after soldering as any remnant traces will be highly corrosive to the steel. Hydrochloric acid based fluxes are not recommended for soldering of stainless steels.

· 4. Flux should be applied with a brush, to only the area being soldered.

· 5. A large, hot iron is recommended. Use the same temperature as for carbon steel, but a longer time will be required because of stainless steel's low thermal conductivity.

· 6. Any type of solder can be used, but at least 50% tin is recommended. Solder with 60-70% tin and 30-40% lead has a better colour match and greater strength.

Brazing (Silver Soldering)

When welding is impractical and a stronger joint than soft soldering is required, brazing may be employed. This method is particularly useful for joining copper, bronze, nickel and other non-ferrous metals to stainless steel. The corrosion resistance of the joint will be somewhat lower than that of the stainless steel, but in normal atmospheric and mildly corrosive conditions brazed joints are satisfactory. Because most brazing operations involve temperatures at which carbide precipitation (sensitisation) can occur in the austenitic grades, low carbon or stabilised grades (304L, 316L or 321) should be used. Ferritic grades such as 430 and 3CR12 can be quenched from the brazing temperatures, but hardenable martensitic grades (410, 420, 431) should not be heated above 760°C when brazing. The free machining grades 303, 416 and 430F should generally not be used as a dark scum forms on the surface when fluxing and heating, which adversely affects the appearance of the steel.

Recommended Procedure for Brazing

Recommended procedure for brazing:

· 1. Use silver brazing alloys with melting points from 590-870°C. Select the alloy for best colour match.

· 2. Remove dirt and oxides from the steel surfaces and apply flux immediately.

· 3. A slightly reducing flame should be played across the joint to heat uniformly.

· 4. For high production work use induction heating or controlled atmosphere furnaces (argon, helium or dissociated ammonia with dew point of about -50°C).

· 5. After brazing remove all remaining flux with high pressure steam or hot water.

· 6. When brazing grade 430 use a silver solder with 3% nickel. This alloy also helps to minimise crevice corrosion when used with austenitic grades.

[citation needed]
Where did you copy/paste that from?

I sincerely appreciate your input, but please read the op more thoroughly/carefully, and don't assume that I was too lazy to consult google before making this thread.

[Alamo]

Yeah that was pretty oblivious reading sorry about that "again" /sigh, as for the site

www.azom.com (http://www.azom.com/details.asp?articleid=1178) A to Z of materials "really helpful site."

I also found your
304 stainless (http://www.azom.com/Details.asp?ArticleID=965) metal looking for which would actually be better and it seems like the brazing would be a better option because of the 304's high bonding point. Also for kicks I would try a metal scrap yard if you have one or home-depot something like that and get a second opinion, worst thing is you have to re heat it clean it and try again sorry again hah :facepalm:.