Form This specification covers an iron-nickel alloy in the form of strip 0.020 to 0.1874 inch (0.51 to 4.760 mm)@ inclusive@ in nominal thickness (see 8.6). Application This strip has been used typically for diaphragms@ leaf springs@ and helical springs@ requiring a precipitation-hardenable alloy with a coefficient of modulus of elasticity of -20 to +20 x 10-6 per degree Fahrenheit from -50 to +150 ??(-36 to +36 x 10-6 per degree Celsius from -46 to +66 ?? after suitable heat treatment@ but usage is not limited to such applications.