mechanical engineering

Carbon steels

• Hard-drawn spring steel
  Low cost; general purpose; low stress; low fatigue life. Temperatures below 120°C. Tensile strength up to 1600 N mm -2.
• Piano (music) wire
  Tougher than harddrawn spring steel; high stress (tensile strength up to 2300 N inm- *); long fatigue life; used for 'small springs'. Temperatures below 120°C.
• Oil-tempered spring steel
  General purpose springs; stress not too high; unsuitable for shock or impact loads. Popular diameter range 3-15 mm.

Alloy steels

• Chrome-vanadium steel
  Best for shock and impact loaL,. Available in oiltempered and annealed condition. Used for internal combustion engine valve spriags. Temperatures up to 220 "C.
• Silicon-manganese steel
  High working stress; used for leaf springs; temperatures up to 220°C. Si1 icon-chromium steel Better than silicon-manganese; temperatures up to 220 "C.
• Stainless steels
  Cold drawn; tensile strength up to 1200Nmm-2. Temperatures from sub-zero to 290 "C, depending on type. Diameters up to 5mm.

Non-ferrous alloys

• Spring brass (70/30)
  Low strength, but cheap and easily formed. Good electrical conductivity.
• Phosphor bronze (5%Sn)
  High strength, resilience, corrosion resistance and fatigue strength. Good electrical conductivity. Tensile strength 770N mm-2. Wire diameters 0.15-7mm. Used for leaf and coil switch springs.
• Beryllium-copper (2 1/4%)
  Formed in soft condition and hardened. High tensile strength. Used for current-carrying brush springs and contacts. Tensile strength 1300Nmm-2.
• Inconel
  Nickel based alloy useful up to 370°C. Exceedingly good corrosion resistance. Diameters up to 7mm. Tensile strength up to 1300Nmm-2.

Moduli of spring materials