Frequently Asked Questions
- Brazing, Welding, Metallizing
- TIG welding alloy C91000
- Quantity of rods per lb.
- Solidus, Liquidus and Brazing range
- Welds cracking
- Tensile strength of brazed joints
- Join aluminum to copper
- Brass versus Bronze
- Repairing cracked musical drum
- Wire size conversion chart
- Key metals melting points
- Wire lengths per pound
- Shielding gas guide
- Standard pipe sizes
- Electrical conductivity of metals
- Types of current for GTAW
- DIN 8513 / AWS 5.8A cross reference
Ask Aufhauser a question
Q. How do I TIG weld alloy C91000?
A: Alloy C91000 is a high tin bronze. For TIG welding, you can use our Phos Bronze A or our Silicon Bronze rod. Phos Bronze A gives better color match. Silicon Bronze gives stronger welds. The TIG welding temperature for both of these filler metals is a little higher than the melting point of the C91000 (1505°F solidus, 1760°F liquidus). Because of this temperature concern, and depending on the thickness of the welded part, you may want to consider brazing. To braze C91000, you may use our PhosCopper 0 alloy.
Q. How many rods per lb. ?
A: The number of rods per pound varies with the alloy and with the diameter.
Q: What is the tensile strength of brazed joints?
A: It all depends. No manufacturer lists the tensile strength of their brazing alloys. This is not to make life difficult for the ultimate consumer. It is because people tend to place too much emphasis on any number that might be published. Design engineers sometimes base designs on a number that is not appropriate for the ultimate use.
In fact, the strength of a brazed joint depends more on the design and the brazing technique rather than on the filler metal used.
Furthermore, tensile strength numbers that Aufhauser has measured apply to material in the wrought state. When the filler metal is used in brazing, it is effectively recast. Recast metal has different properties from the wrought metal.
Empirical testing of various brazed joints has shown that the PSI of the alloy does not correlate directly to the strength of the tested joint. We know some of the factors that influence this process. For example, if the alloy is overheated, the lower melting elements are burned off to a higher degree. This effectively changes the composition of the deposited metal. Thus our advice is to encourage customers to do their own testing of the brazed joint.
But there are some rules of thumb. If customers insist on a certain PSI number, we suggest a number ranging from 60,000-70,000 PSI when tested in the wrought state. Another guideline is that joints properly brazed with Aufhauser Silver Alloys have a shear strength that exceeds three times the shear strength of the thinner, joined metal.
Q: How to join aluminum to copper?
A: It is difficult to braze or weld aluminum to copper, because of the low melting temperature (1018°F) of the aluminum-copper eutectic and its extreme brittleness. By heating and cooling rapidly, however, reasonably ductile joints are made for applications such as copper inserts in aluminum castings. The usual filler metals and fluxes for brazing aluminum to aluminum can be used, or the Silver Alloy filler metals BAg-1 and BAg-1a can be used if heating and cooling are rapid (to minimize diffusion). Pre-tinning the copper surfaces with solder or silver alloy filler metal improves wetting and permits shorter time at brazing temperature. A more practical way to braze aluminum to copper is to braze one end of a short length of aluminum-coated steel tube to the aluminum, and then silver braze the other.
Q: How to make repairs to cracked steel drum and to prevent re-crack over time due to vibrations from tuning and playing the instrument?
A: Brazing repairs may be made to a crack that is several inches in length, a few tenths of a millimeter in separation. The key point to the repair is to heat the crack as quickly as possible, and to work within the limited time when flux is heated to its ideal working temperature. First preheat the area surrounding the crack to relax and to remove thermal stresses. Clean the affected surface joining area. Braze the crack as quickly as possible: apply flux, heat and braze the filler alloy before the flux stops working (usually within 2 minutes). Choose a low-melting alloy such as BAg-1. Clean the joint making sure to remove any flux residue.
Contact Aufhauser with any other questions