CuSn6 - UNS.C51900 Phosphor Bronze Alloys, which is a 6% tin bronze distinguished by a very good combination of strength and electrical conductivity. It is used for connector and current-carrying springs in contacts. Among the 4-8% tin bronze C51900 exhibits a high electrical conductivity, the highest reachable strength is significantly higher than C51100 and C51000. By means of an additional further tempering after the cold forming process the bendability can be further improved.
Its adequate conductivity makes it particularly interesting for springy conductive components. It is wear-resistant, has very good corrosion resistance and can be readily soldered. Due to the higher strength and springiness and good workability, C51900 is used for all types of springs as well as for flexible metal hoses. In addition, it is applied in the paper, pulp, textile and chemical industries, as well as in shipbuilding, mechanical engineering and process equipment manufacture.

Typical Application for C51900 Phosphor Bronze Alloys
Electrical: Stamped Parts,springs, Components of Electrical Engineering, Terminals,Contacts, Switch Parts, Electromechanical Spring Components, Resistance Wire, Electrical Flexing Contact Blades, Electrical Connectors, Electronic Connectors, Wire Brushes, Electronic and Precision Instrument Parts, Fuse Clips, Terminal Brackets, Kettles, Pots, Perforated sheets, Textile Machinery parts
Fasteners: Fasteners
Industrial: Bellows, Textile Machinery, Perforated Sheets, Chemical Hardware, Truss Wire, Mechanical Springs, Sleeve Bushings, Diaphragms, Clutch Disks, Bourdon Tubes, Beater Bar, Welding Rods, Pressure Responsive Elements, Sprinkler Parts, Automotive Parts
Available Sizes:
Custom Diameter & Sizes, Random Mill lengths

Available Products (forms):
Round bars, Flat bars, Square bars, Round Wires, Round Strips
Custom shapes are available upon request.

Chemical Composition:

Sn: 5.50-7.00%
P:  0.03-0.35%
Zn: 0.30% Max.
Fe: 0.10% Max.
Pb: 0.05% Max.
Cu: Balance

Note: Copper plus additions equal 99.50% minimum.

Typical Physical Properties:

Specific Gravity: 8.80 g/cm3
Coefficient of Thermal Expansion per °C: 18.50 x 10-6 (20-300°C)
Electrical Conductivity (% IACS): 15.50 % @ 68 F
Thermal Conductivity: 38.00 Btu · ft/(hr · ft2·oF)at 68F
Modulus of Elasticity in tension: 16000 ksi

Note: 
1). the units are based upon US Customary.
2). the typical physical properties apply to age hardened products.

International Specification:

Rods/Bars/Strips: UNS.C51900, CDA519, ASTM B139, B103, B888, B159
European Standards: CuSn6, JIS C5191, CW 452 K, PB 103