This part of ISO 6892 specifies the method of tensile testing of metallic materials in liquid helium (the boiling point is –269 °C or 4,2 K, designated as 4 K) and defines the mechanical properties that can be determined. This part of ISO 6892 may apply also to tensile testing at cryogenic temperatures (less than –196 °C or 77 K), which requires special apparatus, smaller test pieces, and concern for serrated yielding, adiabatic heating, and strain-rate effects. To conduct a tensile test according to this part of ISO 6892 at 4 K, the test piece installed in a cryostat is fully submerged in liquid helium (He) and tested using displacement control at a nominal strain rate of 10-3 s-1 or less.
Sisällysluettelo
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and designations
5 Principle
6 Apparatus
7 Test piece
7.1 General
7.2 Standard round bar test piece
7.3 Alternatives
7.4 Sub-size test pieces
7.5 Sampling
8 Testing conditions
8.1 Test piece installation
8.2 Cooling procedure
8.3 Rate of testing
9 Procedure
9.1 Determination of original cross-sectional area (So)
9.2 Marking of the original gauge length (Lo)
9.3 Determination of percentage elongation after fracture (A)
9.4 Determination of the 0,2 % proof-strength, plastic extension (Rp0,2)
9.5 Discontinuous yielding strength (Ri)
9.6 Tensile strength (Rm)
9.7 Reduction of area (Z)
10 Test report
11 Measurement uncertainty
Annex A Examples of test pieces for tensile testing in liquid helium (informative)
ISO 6892-1:— Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6892-3 Metallic materials — Tensile testing — Part 3: Method of test at low temperature
ISO 7500-1 Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 6892-1:— Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6892-3 Metallic materials — Tensile testing — Part 3: Method of test at low temperature
ISO 7500-1 Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 9513 Metallic materials — Calibration of extensometer systems used in uniaxial testing