SIST EN 10319-2:2007
(Main)Metallic materials - Tensile stress relaxation testing - Part 2: Procedure for bolted joint models
Metallic materials - Tensile stress relaxation testing - Part 2: Procedure for bolted joint models
This part of EN 10319 specifies the test method for determining the stress relaxation of bolts tensioned in bolted joint models subjected throughout the test to overall constant strain and constant temperature conditions.
Metallische Werkstoffe - Relaxationsversuch unter Zugbeanspruchung - Teil 2: Prüfverfahren mit Schraubenverbindungsmodellen
In diesem Teil von EN 10319 ist das Prüfverfahren zur Bestimmung der Spannungsrelaxation von Schraubenbolzen unter Zugbelastung in Schraubenverbindungsmodellen festgelegt, die während der Prüfung unter konstanter Dehnung und konstanter Temperatur gehalten werden.
Matériaux métalliques - Essai de relaxation en traction - Partie 2: Mode opératoire pour modeles d'assemblages boulonnés
La présente partie de l’EN 10319 spécifie la méthode d’essai pour la détermination de la relaxation de
contrainte de boulons en traction dans des modeles d’assemblages boulonnés et soumis tout au long de
l’essai a des conditions de déformation globalement constante et de température constante.
Kovinski materiali – Preskušanje sprostitve pri natezni obremenitvi – 2. del: Postopek za modele vijačnih zvez
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Metallic materials - Tensile stress relaxation testing - Part 2: Procedure for bolted joint modelsMatériaux métalliques - Essai de relaxation en traction - Partie 2: Mode opératoire pour modeles d'assemblages boulonnésMetallische Werkstoffe - Relaxationsversuch unter Zugbeanspruchung - Teil 2: Prüfverfahren mit SchraubenverbindungsmodellenTa slovenski standard je istoveten z:EN 10319-2:2006SIST EN 10319-2:2007en77.040.10Mehansko preskušanje kovinMechanical testing of metalsICS:SLOVENSKI
STANDARDSIST EN 10319-2:200701-marec-2007
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 10319-2October 2006ICS 77.040.10 English VersionMetallic materials - Tensile stress relaxation testing - Part 2:Procedure for bolted joint modelsMatériaux métalliques - Essai de relaxation en traction -Partie 2: Mode opératoire pour modèles d'assemblagesboulonnésMetallische Werkstoffe - Relaxationsversuch unterZugbeanspruchung - Teil 2: Prüfverfahren mitSchraubenverbindungsmodellenThis European Standard was approved by CEN on 6 August 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 10319-2:2006: E
EN 10319-2:2006 (E) 2 Contents Foreword.3 1 Scope.4 2 Normative references.4 3 Terms and definitions.4 4 Symbols and designations.5 5 Principle.6 6 Apparatus.6 6.1 Bolted joint model device.6 6.1.1 General.6 6.1.2 Bolted joint model A.7 6.1.3 Bolted joint model bolt B.7 6.2 Extension measuring device.7 6.2.1 Measuring device for the overall length.7 6.2.2 Measuring device for the strain.7 6.3 Heating device.7 6.3.1 General purpose.7 6.3.2 Permissible temperature deviations.7 6.3.3 Temperature measurement.8 6.3.4 Calibration of the thermocouples and temperature measuring system.8 7 Shape, dimensions and preparation of bolted joint models.9 7.1 Shape and dimensions.9 7.2 Preparation.10 7.3 Determination of the original cross-sectional area.10 8 Test procedure.10 8.1 General.10 8.2 Tensioning of the bolt.10 8.2.1 General.10 8.2.2 Tensioning with bolted joint model A.11 8.2.3 Tensioning with bolted joint model B.11 8.3 Determination of the initial stress of the bolt.11 8.4 Heating, holding at temperature and cooling of the bolted joint model.11 8.5 Determination of the residual elastic strain.11 8.5.1 General.11 8.5.2 Unloading the bolt.12 8.5.3 Residual elastic strain with bolted joint model A.12 8.5.4 Residual elastic strain with bolted joint model B.12 8.5.5 Determination of the residual stress.12 9 Accuracy of the results.13 9.1 Expression of the results.13 9.2 Uncertainty.13 10 Test report.13 Annex A (informative)
Information concerning different types of thermocouples.21 Annex B (informative)
Information concerning methods of calibration of thermocouples.22 Bibliography.23
EN 10319-2:2006 (E) 3 Foreword This document (EN 10319-2:2006) has been prepared by Technical Committee ECISS/TC 1 “Steel - Mechanical testing”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2007, and conflicting national standards shall be withdrawn at the latest by April 2007 This European Standard consist of the following parts under the general title Metallic materials – Tensile stress relaxation testing: Part 1: Procedure for testing machines Part 2: Procedure for bolted joint models According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EN 10319-2:2006 (E) 4 1 Scope This part of EN 10319 specifies the test method for determining the stress relaxation of bolts tensioned in bolted joint models subjected throughout the test to overall constant strain and constant temperature conditions. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Not applicable. 3 Terms and definitions For the purpose of this European Standard, the following terms and definitions apply. 3.1 nominal diameter (d) diameter of the bolt in the cylindrical length Lc 3.2 thread diameter (D) diameter of the threaded ends of the bolt 3.3 cylindrical length (Lc) length of the cylindrical reduced section of the bolt 3.4 reference length (Lr) base length of the bolt used for calculating strain 3.5 overall length (Lt) overall length of the bolt 3.6 original cross-sectional area (So) cross-sectional area of the cylindrical length of the bolt determined at ambient temperature prior to testing: 42/dSoπ= 3.7 extension increase in the overall length Lt A distinction is made between: 3.7.1 extension during tensioning (∆∆∆∆Lo) extension of the overall length Lt of the bolt during tensioning
EN 10319-2:2006 (E) 5 3.7.2 elastic reverse extension during unloading (∆∆∆∆Lt) back extension of the overall length Lt of the bolt during unloading at the end of the test 3.8 strain extension divided by the reference length Lr A distinction is made between:
3.8.1 specified initial elastic strain (εεεεeo) initial elastic strain of the bolt at the beginning of the test
NOTE The specified initial elastic strain is calculated from the extension during tensioning ∆Lo (reo/LLo∆=ε) or is measured directly on the cylindrical length of the bolt with strain gauges. 3.8.2 residual elastic strain (εεεεer) strain calculated from the reverse extension ∆Lt (rterLL∆ε=) or directly measured in the cylindrical length of the bolt with strain gauges during unloading of the bolt at the end of the test 3.9 stress at any time during the test, force divided by the original cross-sectional area (So) of the bolt between: A distinction is made between: 3.9.1 initial stress (σσσσοοοο) stress at the start of the test, expressed as a product of the static elastic modulus ET at the test temperature and the specific initial elastic strain εeo eoTεσ×=Eo
(1) 3.9.2 residual stress (σσσσrt) value to which the stress of the bolt has relaxed at the specified time t, after the test, expressed as the product of the elastic modulus ET or ETd and the residual elastic strain erTrtεσ×=E
(2) NOTE The dynamic modulus of elasticity ETd should be taken, if the static modulus of elasticity ET at test temperature is not available. 4 Symbols and designations The symbols and corresponding designations are given in Table 1.
EN 10319-2:2006 (E) 6 Table 1 — Symbols and designations Symbol Unit Designation d mm Nominal diameter of the cross-section of the cylindrical length of the bolt Lc mm Cylindrical length of the bolt Lr mm Reference length of the bolt Lt mm Overall length of the bolt So mm2 Original cross-sectional area of the cylindrical length of the bolt εeo
Specified initial elastic strain εer
Residual elastic strain ET GPa Static modulus of elasticity at test temperature ETd GPa Dynamic modulus of elasticity at test temperature σo MPaa Initial stress σrt MPa Residual stress at time t t h Test duration T °C Specified temperature Ti °C Indicated temperature a 1 MPa=1 N/mm2. 5 Principle The test consists of tensioning a test piece in the form of a bolt in a bolted joint model device to a specified initial elastic strain, subjecting the bolt to that strain for specific temperature and time and determining the residual stress in the bolt by unloading at the end of the test. The constant tensile strain and residual stress are derived from an extension measurement referring to the overall length of the bolt (bolted joint model A) or from strain gauge measurements at the cylindrical length of the bolt (bolted joint model B), all measurements being performed at room temperature. 6 Apparatus 6.1 Bolted joint model device 6.1.1 General In the bolted joint model, a bolt with a cylindrical length and threaded ends is tensioned by two nuts against a flange (Figure 1). Bolts, flanges and nuts shall be of the same material.
EN 10319-2:2006 (E) 7 The bolted joint model shall apply a force along the axis of the bolt in such a way that inadvertent bending or torsion of the bolt are minimal. The flange shall have a sufficient stiffness. Unloading the bolt at the end of the test shall be possible by destroying the flange or a nut. 6.1.2 Bolted joint model A In bolted joint model A (Figure 2) the ends of the bolt allow the application of an extension measuring device (Figure 4). 6.1.3 Bolted joint model bolt B In bolted joint model B the flange allows access for the application of two opposite strain gauges onto the cylindrical length of the bolt (Figure 3). 6.2 Extension measuring device 6.2.1 Measuring device for the overall length With the measuring device (Figure 4) the extension of the bolt of the bolted joint model A shall be measured at room temperature with and without tensioning at the beginning and at the end of the test. The accuracy of the measurement with a dial gauge shall be ± 0,001 mm. NOTE The use of a reference bar (Figure 4) facilitates the extension measurements. 6.2.2 Measuring device for the strain With the measuring device (Figure 5) the strain of the cylindrical length of the bolt of bolted joint model B shall be measured at room temperature without and with tensioning at the beginning and the end of the test. Two active strain gauges are mounted on opposite sides at the cylindrical length of the bolt. They are connected in a series for measuring additional bending. The strain gauges should have a gauge length of at least 6 mm. NOTE To avoid undesired reaction products, which may be gaseous or firmly adhere to the surface of the bolt, the strain gauges, including the adhesive, have to be removed before the model is heated up to the test temperature. To compensate for variations in strain caused by room temperature variations, two passive compensating strain gauges shall be mounted on a reference piece of material identical to the material of the bolted joint model in the initial state and shall also be connected in series. The total configuration of all the strain gauges mounted on the bolted joint model and on the reference piece should be set up as a half-bridge circuit. The accuracy of the measuring device shall be ± 1 . 10-6 in strain. 6.3 Heating device 6.3.1 General purpose The heating device shall heat the bolted joint model, hold it at the specified temperature for a specified time and cool it down to room temperature. The heating device shall be capable of performing limited heating and cooling rates. 6.3.2 Permissible temperature deviations The permitted deviations between the indicated temperature, Ti of the bolted joint model, the specified temperature, T and the maximum admissible temperature gradient shall be as given in Table 2. The temperature gradient is the maximum difference between the temperatures indicated by the measuring thermocouples attached to the bolted joint model.
EN 10319-2:2006 (E) 8 Table 2 — Permitted deviations between Ti, T and the maximum admissible temperature gradient Specified temperature T Permitted deviation between Ti and T Maximum admissible temperature gradient °C °C °C T ≤ 600
± 3 2 600 < T ≤ 800 ± 4 3 800 < T ≤ 1 000
± 5 3 For specified temperatures greater than 1 000 °C, the permitted values shall be defined by agreement between the parties concerned. The indicated temperatures Ti, are the temperatures measured at the surface of the cylindrical length of the test piece, errors from all sources being taken into account. NOTE Instead of measuring the temperature at the surface of the bolted joint model, it is permitted to indirectly measure the temperature of each heating zone of the furnace provided it is demonstrated that the tolerance defined above is fulfilled. The variation of the room temperature during all extension measurements shall not exceed ± 2 °C. 6.3.3
Temperature measurement 6.3.3.1 General Temperature indicator shall have a resolution (sensitivity) of at least 0,5 °C and the temperature measuring equipment shall have an accuracy of ± 1 °C. 6.3.3.2 Number of thermocouples It is recommended that at least one thermocouple should be used for each bolted joint model and where only one thermocouple is used, it should be positioned at the middle of the bolted joint model. In the case of indirect temperature measurement, regular control measurements are required to determine the differences between the thermocouple(s) of each heating zone and a significant number of model bolts within a given zone. The non-systematic components of the temperature differences shall not exceed ± 2 °C up to 800 °C and ± 3 °C above 800 °C. The total number of thermocouples may not be reduced to less than three, if the thermocouples located at suitable places in the furnace and the indicated temperature do not exceed the permitted deviations given in Table 2. 6.3.3.3 Thermocouples In all cases, thermocouple junction shall make good thermal contact with the surface of the bolted joint model and shall be screened from direct radiation from the heating source. The remaining portions of the wires within the furnace shall be thermally shielded and electrically insulated. NOTE This clause is not applicable in the case of indirect temperature measurement. 6.3.4 Calibration of the thermocouples and temperature measuring system NOTE Information concerning different types of thermocouples is given in Annex A.
EN 10319-2:2006 (E) 9 6.3.4.1 Calibration of thermocouples Thermocouples used
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