Standard Test Method for Tensile Strain-Hardening Exponents (n -Values) of Metallic Sheet Materials

Importancia y uso:

5.1 This test method is useful for estimating the strain at the onset of necking in a uniaxial tension test (1). Practically, it provides an empirical parameter for appraising the relative stretch formability of similar metallic systems. The strain-hardening exponent is also a measure of the increase in strength of a material due to plastic deformation.

5.2 The strain-hardening exponent may be determined over the entire plastic stress-strain curve or any portion(s) of the stress-strain curve specified in a product specification.

Note 4: The engineering strain interval 10 % – 20 % is commonly used for determining the strain-hardening exponent, n, of formable low-carbon steel products

5.3 This test method is not intended to apply to any portion of the true stress versus true strain curve that exhibits discontinuous behavior; however, the method may be applied by curve-smoothing techniques as agreed upon.

Note 5: For example, those portions of the stress-strain curves for mild steel, aluminum, or other alloys that exhibit yield point and Lüders band elongation, twinning, or Portevin–Le Chatelier effect (PLC) may be characterized as behaving discontinuously.

Note 6: Caution should be observed in the use of curve-smoothing techniques as they may affect the n-value.

5.4 This test method is suitable for determining the tensile stress-strain response of metallic sheet materials in the plastic region prior to the onset of necking.

5.5 The n-value may vary with the displacement rate or strain rate used, depending on the metal and test temperature.

Subcomité:

E28.02

Referida por:

A0653_A0653M-23, A0792_A0792M-23, A1008_A1008M-24, A0875_A0875M-23, A0792_A0792M-23, A1046_A1046M-24, A0463_A0463M-22, A1083_A1083M-23, E1006-21, A1088-13R19, A0653_A0653M-23, E2448-22, A1079-17R23, E2218-23, E0706-23

Volúmen:

03.01

Número ICS:

77.140.50 (Flat steel products and semi-products)