etpm
Veteran Member
Because of a silver soldering thread in this forum I thought it might help if I posted this here. Because silver bearing plumbing solder is now widely available in hardware stores folks should know about how strong 95/5 tin/silver soft solder is. And how some companies will publish information that makes it seem stronger than it is.
The 95% tin, 5% silver soft solder has a tensile strength of 3600 PSI. That's the yield strength, which is the most important number. If two pieces of steel 1 square inch in area are joined with 95/5 tin silver solder and pulled on they will start to pull apart when 3600 pounds of force are applied.
The shear strength is much higher, about 10,000 PSI. So if the same joint was pulled on sideways it would take 5 tons of force to start the joint moving. Some companies will say their solder has this high number of strength implying, but not explicitly saying, this is the tensile strength.
But even though silver brazing alloy is more than 10 times stronger than 95/5 soft solder it doesn't always need to be used. For example, if you need a really long drill for a wiring job then drilling a hole in the end of a long steel rod and then soldering the drill bit into steel rod will work fine. Just make sure the hole is very close in size to the drill shank because the solder loses strength if it too thick. I have made many drill extensions like this in my career as a machinist.
If you do decide to use plumbing solder make sure it is the 95/5 tin/silver alloy, not the tin/antimony alloy.
Eric
The 95% tin, 5% silver soft solder has a tensile strength of 3600 PSI. That's the yield strength, which is the most important number. If two pieces of steel 1 square inch in area are joined with 95/5 tin silver solder and pulled on they will start to pull apart when 3600 pounds of force are applied.
The shear strength is much higher, about 10,000 PSI. So if the same joint was pulled on sideways it would take 5 tons of force to start the joint moving. Some companies will say their solder has this high number of strength implying, but not explicitly saying, this is the tensile strength.
But even though silver brazing alloy is more than 10 times stronger than 95/5 soft solder it doesn't always need to be used. For example, if you need a really long drill for a wiring job then drilling a hole in the end of a long steel rod and then soldering the drill bit into steel rod will work fine. Just make sure the hole is very close in size to the drill shank because the solder loses strength if it too thick. I have made many drill extensions like this in my career as a machinist.
If you do decide to use plumbing solder make sure it is the 95/5 tin/silver alloy, not the tin/antimony alloy.
Eric
