BS ISO 6892-4:2015 pdf download – Metallic materials — Tensile testing Part 4: Method of test in liquid helium
1 sScope
This part of lSO 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 thatcan be determined.
This part of lSO 6892 may apply also to tensile testing at cryogenic temperatures (less than -196 C or77K), which requires special apparatus, smaller test pieces, and concern for serrated yielding,adiabaticheating, and strain-rate effects.
To conduct a tensile test according to this part of lSO 6892 at 4 K, the test piece installed in a cryostat isfully submerged in liquid helium (He) and tested using displacement control at a nominal strain rate of10-3 s-1 or less.
NOTE The boiling point of the rare 3He isotope is 3,2K. Usually, the tests are performed in He or a mixtureof 3He and 4He with a high concentration of 4He.Therefore, the temperature is, as designated before,4K.
2Normative references
The following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application.For dated references,only the edition cited applies. For undatedreferences, the latest edition of the referenced document (inciuding any amendments) applies.
IS0 6892-1:—1),Metallic materials —Tensile testing —Part 1: Method of test at room temperatureISO 6892-3,Metallic materials —Tensile testing — Part 3:Method of test at low temperature
ISO 7500-11,Metallic materials — Calibration and verification of static uniaxial testing machines — Part1:Tension /compression testing machines —Calibration and verification of the force-measuring systemISO 9513,Metallic materials —Calibration of extensometer systems used in uniaxial testing
3Terms and definitions
For the purpose of this document, the terms and definitions given in IS06892-1 and in ISO 6892-3 apply.3.1
adiabatic heating
internal heating of a test piece resulting from deformation under conditions such that the heat generatedby plastic work cannot be quickly dissipated to the surrounding cryogen
axial strain
longitudinal strains measured at opposite or equally spaced surface locations on the sides of thelongitudinal axis of symmetry of the test piece
Note 1 to entry:The longitudinal strains are measured using two or more strain-sensing transducers located atthe mid-length of the parallel length.
bending strain
difference between the strain at the surface of the test piece and the axial strain
Note 1 to entry: The bending strain varies around the circumference and along the parallel length of the test piece.
vacuum-insulated container for cryogenic fluids3.5
discontinuous yielding strengthR
peak stress at the initiation of the first measurable serration on the stress-strain curves
tensile cryostat
test apparatus for applying tensile forces to test pieces in cryogenic environmentsNote 1 to entry: See Figure 2.