How to identify the type of copper alloy

How to identify the type of copper alloy?
White copper, brass, red copper (also known as “red copper”), and bronze (blue-gray or gray-yellow) are distinguished by color. Among them, white copper and brass are very easy to distinguish; red copper is pure copper (impurities <1%) and bronze (other alloy components are about 5%), which is slightly difficult to distinguish. When unoxidized, the color of red copper is brighter than that of bronze, and the bronze is slightly cyan or yellowish dark; after oxidation, the red copper becomes black, and the bronze is turquoise (harmful oxidation of water) or chocolate.
Classification and welding characteristics of copper and copper alloys:
(1) Pure copper: Pure copper is often called red copper. It has good electrical conductivity, thermal conductivity and corrosion resistance. Pure copper is represented by the letter +T}} (copper), such as Tl, T2, T3, etc. The oxygen content is extremely low, and pure copper with no more than 0.01% is called oxygen-free copper, which is represented by TU (copper free), such as TU1, TU2, etc.
(2) Brass: The copper alloy with zinc as the main alloying element is called brass. Brass uses +H; (yellow) means H80, H70, H68, etc.
(3) Bronze: In the past, the alloy of copper and tin was called bronze, but now copper alloys other than brass are called bronze. Commonly used are tin bronze, aluminum bronze and min bronze. Bronze is represented by “Q” (cyan).
The welding characteristics of copper and copper alloys are: ① difficult to fuse and easy to deform; ② easy to generate hot cracks; ③ easy to generate pores
Copper and copper alloy welding mainly adopts gas welding, inert gas shielded welding, submerged arc welding, brazing and other methods.
Copper and copper alloys have good thermal conductivity, so they should generally be preheated before welding, and large line energy should be used for welding. The hydrogen tungsten arc welding adopts DC positive connection. In gas welding, neutral flame or weak carbonization flame is used for copper, and weak oxidizing flame is used for brass to prevent the evaporation of zinc.