Tensile testing of metallic materials is specified co-ordinate to European EN 10002 standard. This standards consists of v parts:

  • EN 10002-one - Method of testing at ambient temperature
  • EN 10002-ii - Verification of the force measuring system of the tensile testing machine
  • EN 10002-3- Calibration of forcefulness proving instruments used for the verification of uniaxial testing machines
  • EN 10002-iv - Verification of extensometers used in uniaxial testing
  • EN 10002-five - Method of testing at elevated temperatures

In this article the terms, definitions and designation for tensile exam made at ambience temperature is described. The test involves straining a exam slice in tension, generally to fracture, for the purpose of determining mechanical properties.

Terms and definitions

For the purpose of this European Standard, the following terms and definitions employ:

  • gauge length (L) - length of the cylindrical or prismatic portion of the test piece on which elongation is measured. In particular, a distinction is made betwixt:
    • original gauge length (50o) - gauge length before application of force
    • terminal estimate length (Lu) - gauge length after rupture of the exam piece
    • parallel length (Lc) - parallel portion of the reduced section of the test piece
  • elongation - increase in the original estimate length (Fiftyo) at whatever moment during the test
  • pct elongation - elongation expressed as a percentage of the original gauge length (Fiftyo)
  • per centum permanent elongation - increment in the original gauge length of a exam piece after removal of a specified stress, expressed equally a percentage of the original guess length (Lo)
  • percentage elongation after fracture (A) - permanent elongation of the gauge length after fracture (Lu - Lo), expressed as a percentage of the original gauge length (Lo). In the case of proportional examination pieces, where original gauge length is other than 5.65√Southo, the symbol A should be supplemented by an alphabetize indicating the coefficient of proportionality used (A11,iii for Lo=11.iii√ And so) or by an alphabetize indicating the original estimate length (A80 mm for Fiftyo=80 mm)
  • percentage elongation at maximum force - increase in the gauge length of the exam piece at maximum force, expressed as a percentage of the original gauge length (Lo)
  • extensometer gauge length (Le) - length of the parallel portion of the test piece used for the measurement of extension by ways of an extensometer
  • extension - increase in the extensometer gauge length (50e) at a given moment of the test
  • pct permanent extension - increase in the extensometer gauge length, after removal from the exam piece of a specified stress, expressed as a percent of the extensometer approximate length (Fiftyeast)
  • percent yield bespeak extension (Aeastward) - in discontinuous yielding materials, the extension between the start of yielding and the showtime of uniform work hardening
  • percentage reduction of expanse (Z) - maximum change in cross-sectional area which has occurred during the test (So - Su) expressed as a pct of the original cross-sectional surface area (Southo)
  • maximum force (Fk) - the greatest strength which the exam piece withstands during the test in one case the yield signal has been passed. For materials, without yield point, it is the maximum value during the exam
  • stress - force at whatsoever moment during the examination divided past the original cantankerous-sectional area (So) of the exam piece
  • tensile forcefulness (Ryard) - stress corresponding to the maximum force (Fm)
  • yield strength - when the metallic textile exhibits a yield miracle, stress respective to the betoken reached during the test at which plastic deformation occurs without any increment in the force. A distinction is made between:
    • upper yield force (ReH) - value of stress at the moment when the starting time subtract in strength is observed
    • lower yield strength (ReL) - lowest value of stress during plastic yielding, ignoring whatever initial transient furnishings
  • proof strength, non-proportional extension (Rp) - stress at which a non-proportional extension is equal to a specified percentage of the extensometer gauge length (Le). The symbol used is followed by the suffix giving the prescribed percentage, such as Rp0,2
  • proof forcefulness, total extension (Rt) - stress at which total extension (elastic extension plus plastic extension) is equal to a specified percentage of the extensometer gauge length (Ldue east). The symbol used is followed past the suffix giving the prescribed percentage, such equally Rt0,5
  • permanent ready forcefulness (Rr) - stress at which, afterwards removal of force, a specified permanent elongation or extension expressed respectively equally a percent of the original gauge length (Lo) or extensometer approximate length (Le) has not been exceeded
  • fracture - phenomena which is deemed to occur when total separation of the exam piece occurs or force decreases to get nominally nix

Symbols and designations

Symbols and corresponding designations of the test slice are given in table one.

The shape and dimensions of the test pieces depend on the shape and dimensions of the metal product from which the test pieces are taken (Figure1). Their cantankerous-section may be circular, foursquare, rectangular, annular or, in special cases, of some other shape. The examination piece is commonly obtained by machining a sample from the product or a pressed bare or casting. Even so, products of constant cross-section and as bandage examination pieces may be tested without being machined.

Tabular array 1. Symbols and designations of the test piece.

Reference (Figure1) Symbol Unit of measurement Designation
ane. a mm Thickness of a flat test slice or wall thickness of a tube
ii. b mm Width of the parallel length of a apartment test piece or average width of the longitudinal strip taken from a tube or width of flat wire
three. d mm Diameter of the parallel length of a circular examination slice, or diameter of round wire or internal diameter of a tube
4. D mm External diameter of a tube
five. Lo mm Original gauge length
- L`o mm Initial gauge length for determination of Ag
vi. 50c mm Parallel length
- Fiftydue east mm Extensometer estimate length
7. Lt mm Total length of test slice
eight. 50u mm Final guess length after fracture
- L`u mm Final guess length after fracture for determination of Ag
9. Due southo mmtwo Original cantankerous-exclusive expanse of the parallel length
10. Su mm2 Minimum cantankerous-sectional area later fracture
- thou - Coefficient of proportionality
eleven. Z % Percentage reduction of area: (So - Su) / So x 100
12. - - Gripped ends
Figure 1. Typical standard test piece

The test piece shall exist held by suitable means such equally wedges, screwed grips, parallel jaw faces, shouldered holders, etc. Every effort should be made to ensure that pieces are held in such a mode that the tension is applied as axially as possible in gild to minimize bending. This is very important for testing brittle materials or when determining proof or yield forcefulness.

For determination of pct elongation, the two broken examination pieces are advisedly fitted dorsum together so that their centrality lie in a straight line. Elongation later on fracture shall be determined to the nearest 0.25 mm with a measuring device with a sufficient resolution and the value of percentage elongation after fracture shall exist rounded to the nearest 0.5% (Table ii). On the Figure two schematic definitions of elongation are given.

Table 2. Different types of elongation

Reference (Figure 2) Symbol Unit of measurement Elongation
13. - mm Elongation afterwards fracture: Lu - Lo
14. A % Percentage elongation afterwards fracture: (50u - Fiftyo) / Lo x 100
15. Aeastward % Pct yield point extension
- Lk mm Extension at maximum forcefulness
sixteen. Agrand % Percentage not-proportional elongation at maximum force (Fone thousand)
17. Agt % Percent total elongation at maximum force (Fg)
eighteen. At % Percentage full elongation at fracture
xix. - % Specified percentage not-proportional extension
20. - % Percentage total extension
21. - % Specified per centum permanent set extension or elongation
Figure 2. Definitions of elongation

The designations and related curves for yield, proof and tensile strength are given in the Tabular array 3 and on the Figure iii.

Table 3. Symbols and designations for unlike types of strength

Reference (Figure 3) Symbol Unit Force and strength
22. Fm N Maximum forcefulness
- - - Yield strength -Proof strength -Tensile forcefulness
23. ReH MPa Upper yield strength
24. ReL MPa Lower yield force
25. Rone thousand MPa Tensile strength
26. Rp MPa Proof forcefulness, non-proportional extension
27. Rr MPa Permanent set forcefulness
28. Rt MPa Proof force, total extension
- East MPa Modulus of elasticity
Figure 3. Definitions of upper and lower yield strengths for unlike types of curves

The examination written report shall contain reference to the standard, identification of the test piece, specified material, type of the examination piece, location and direction of sampling test pieces and test results. In the absenteeism of sufficient data on all types of metallic materials it is not possible, at nowadays, to gear up values of uncertainty for the different properties measured by tensile test.