GOST R ISO 17641-1-2011

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  ГОСТ Р ИСО 17641-1-2011

GOST R ISO 17641−1-2011 destructive Testing of welds of metallic materials. Test on resistance to hot cracking in welded joints. The arc welding processes. Part 1. General provisions

GOST R ISO 17641−1-2011

Group B09
NATIONAL STANDARD OF THE RUSSIAN FEDERATION

DESTRUCTIVE TESTING OF WELDED JOINTS OF METALLIC MATERIALS

Test on resistance to hot cracking in welded joints. The arc welding processes

Part 1

General provisions

Destructive tests on welds in metallic materials. Hot cracking tests for weldments. Arc welding processes. Part 1. General

OKS 25.160.40

Date of introduction 2013−01−01

Preface

The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004 «Standardization in the Russian Federation. The main provisions"

Data on standard

1 PREPARED by the Federal state institution «Scientific-educational center «welding and control» at MGTU im. N. Uh. Bauman» (FGU NUCS computer. N. Uh. Bauman), the National Agency for control and welding (NAKS) on the basis of their own authentic translation into the Russian language of the standard referred to in paragraph 4

2 SUBMITTED by the Technical Committee for standardization TC 364 «welding and allied processes"

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology dated 30 November 2011 N 661-St

4 this standard is identical to international standard ISO 17641−1:2004* «Destructive testing of welds of metallic materials. Test on resistance to hot cracking in welded joints. The arc welding processes. Part 1. General provisions» (ISO 17641−1: «in 2004, Destructive tests on welds in metallic materials — Hot cracking tests for weldments — Arc welding processes — Part 1: General»)
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* Access to international and foreign documents mentioned here and below, you can get a link on the website shop.cntd.ru. — Note the manufacturer’s database.

In applying this standard it is recommended to use instead of the referenced international standards corresponding national standards of the Russian Federation, details of which are given in Appendix YES

5 INTRODUCED FOR THE FIRST TIME


Information about the changes to this standard is published in the annually issued reference index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet

Introduction

ISO 17641−1 by the European Committee for standardization (CEN) in collaboration with technical Committee ISO/TC 44 «welding and allied processes», Subcommittee SC 5 «Testing and weld inspection» in accordance with the Agreement on technical cooperation between ISO and SEN (Vienna Agreement).

ISO 17641 consists of the following parts, under the General name of «Destructive testing of welds of metallic materials. Test on resistance to hot cracking in welded joints. The arc welding processes»:

— part 1. General provisions;

— part 2. Tests with the natural stiffness;

— part 3. Tests with the application of external loads (a technical report).

1 Scope

This standard contains the basic provisions relating to formation of hot cracks in the weld metal and the base metal, and the tests used to evaluate the resistance to formation of these cracks in arc welding.

Part 2 (tests with natural hardness) sets the tests that should be used to evaluate the resistance to hot cracking of the weld metal. The strain that causes the formation of cracks are created due to the stiffness of the welded junction.

Part 3 (testing with the application of an external load) describes tests that can be used to evaluate the resistance to hot cracking of the base metal and the weld metal. The strain that causes the formation of cracks, are created by loading the tested sample by an external force.

Note — the Tests given in part 3, require the use of non-standard special equipment. Laboratories use different procedures, the testing conditions and sample sizes. Therefore, although the reproducibility within a single laboratory is usually good, when tested in different laboratories, discrepancies do occur.

2 Normative references

This standard uses the regulatory references to the following international standards. For dated references, subsequent amendments to or changes in any of these publications is valid for present standard only after the introduction of amendments and changes to it.

EN ISO 17641−2:2005 Destructive tests of welds in metallic materials. Testing of the welded components on the hot cracking in arc welding process. Part 2. Self-limiting testing (ISO 17641−2:2005)

EN ISO 17641−2:2005 Destructive tests on welds in metallic materials — Hot cracking tests for weldments — Arc welding processes — Part 2: Self-restraint tests (ISO 17641−2:2005)

SAINT ISO/17641−3:2005 Destructive tests of welded joints of metallic materials. Test on resistance to hot cracking in welded joints. The arc welding processes. Part 3. Tests with the application of an external load (ISO/17641−3:2005)

CEN ISO/TR 17641−3:2005 Destructive tests on welds in metallic materials — Hot cracking tests for weldments — Arc welding processes — Part 3: Externally loaded tests (ISO/TR 17641−3:2005)

3 Terms and definitions

This standard applies the following terms with respective definitions:

3.1 hot cracks (hot cracks): discontinuity of the material occurring at high temperatures along the grain boundary (dendrite boundaries), when the deformation or rate of strain exceeds a certain level.

Note — Small cracks, visible only at magnification more than 50 times, often referred to as ministrokes.

3.1.1 crystallization cracks (solidification cracks) Hot cracks formed during solidification of the liquid phase of the weld metal.

Note — they Usually come to the surface of the weld, but sometimes can be under the surface.

3.1.2 phase separation cracks (liquation cracks) Hot cracks formed during melting likutov in the heat affected zone (HAZ) of the base metal or in multi-pass joints, when the weld metal is reheated during a subsequent weld passes.

3.1.3 cracks, caused by a drop in ductility (ductility dip cracks) Hot cracks are formed during welding due to the lower high-temperature plasticity. As phase separation cracks they can occur in the HAZ or in multi-pass welds.

3.2 tests with a natural stiffness (self-restraint tests): Tests in which the deformation of the seam sample is due to the stresses generated during welding rigidly fixed node.

3.3 tests with the application of an external load (externally loaded tests): Tests in which the deformation of the seam sample is due to the stresses generated under the action of external force generated by special test equipment.

4 Indicators, symbols and units

Applied in standard indicators, symbols and units given in table 1.


Table 1 — Parameters, symbols and units

5 fundamentals of the theory of formation of hot cracks

Hot cracks occur in the weld HAZ and the base material, when the deformation developing during cooling of the welded joint or under the influence of the outside, superior ductility in a certain area of the welded connection. They are sized from very small exudation of fractures (length less than 1 mm) in the HAZ or multi-pass joints to large crystallization cracks, which may extend the entire length of the welded joints.

Note 1 — These cracks should not be confused with cold cracks that always occur at temperatures below 200 °C.


Hot cracks are not limited to specific alloy systems. They can occur in steels, including corrosion-resistant alloys based on Nickel, copper and aluminum. Causes of hot cracks a lot, but they usually occur when the local plasticity is insufficient to counteract developing welding deformations. The lack of plasticity may depend on the properties of the microstructure and orientation (relative to the direction of deformation) and in some cases from the presence of the brittle inclusions and layers with a low melting point. In this regard, some alloy system is very sensitive to the presence of impurities such as sulfur, phosphorus, lead and other. It is generally accepted that austenite single-phase microstructure, especially of the weld metal in one form or another are prone to hot cracking. The content of impurities in these steels and alloys affects the appearance of cracks.

Note 2 — the Exact mechanism of formation of hot cracks is not yet fully understood.

6 Types of tests

6.1 Testing with natural hardness

These tests depend on the rigidity (fixation) of the welded site in which deformation occurs, sufficient to cause cracking. Tests with the natural stiffness include testing:

a) which consists in welding rigidly fixed site and immediate verification of the test seam for cracks;

b) which consists in welding a butt weld with full penetration, which cut the sample subjected to additional strain for the detection of previously existing hot cracks (especially cracks), make it easier to detect their directions and sizes. For the destruction of post-weld applied tension or bending. They are not intended for initiation of new cracks.

Tests under the welding stresses are suitable only for the evaluation of hot cracking of weld metal.

6.2 Testing with the application of an external load

These tests include external loading of the specimen during the welding process or the welded sample, which is simultaneously heated and loaded.

Tests with the application of external loads include the test:

a) in which the load is applied when performing the weld;

b) in which the weld is reheated and simultaneously loaded to get the opportunity to assess the propensity for crack initiation.

These tests external load is suitable for the assessment of hot cracking of weld metal, base metal and heat affected zone.

7 description of the tests

7.1 Testing with natural hardness

7.1.1 General provisions

Details of the test procedures given in EN ISO 17641−2.

7.1.2 Test for resistance to hot cracking in the weld t-joints (T-joint weld cracking test)

The test procedure is designed to assess the tendency to the occurrence of crystallization cracks metal single-pass fillet weld. Used three types of specimen with the increasing of the sample to the sample stiffness, which is provided by increasing the thickness of the sheet and/or application of the test node in the ribs. The assessment is essentially qualitative, since the direct measurement of welding stresses is not available. The evaluation is based on the length and position of cracks (if any) of the test weld.

7.1.3 tensile Test of the weld metal (weld metal tensile test)

This test is intended to evaluate the resistance of weld metal cut from the butt joint, the formation of phase separation cracks and cracks caused by falling of plasticity. The failure of cylindrical specimen cut from a butt weld opens cracks that occurred during welding. When checking neighboring fracture region of the crack can be detected and measured.

Note — See. EN ISO 17641−2, figures 2 and 3.

7.1.4 Test longitudinal bending (longitudinal bend test)

This test is intended to evaluate the resistance to cracking during solidification, liquation and fall of the ductility of weld metal butt welds. Bending of longitudinal specimens cut from the butt joint, opens arising during welding cracks that can be detected and measured.

Note — See. EN ISO 17641−2, figures 4 and 5.

7.2 Tests with the application of an external load

7.2.1 General provisions

Details of the test procedures is given in SAINT ISO/17641−3.

7.2.2 the Test of tensile with heating (hot tensile test)

Resistance to hot cracking is determined by performing the tests of stretching with heating, simulate the welding thermal cycle. To evaluate the resistance to crystallization and phase separation cracks, use different procedures and sample sizes:

a) to simulate the occurrence of crystallization cracks, the sample is heated to the melting temperature, and the equipment clamps fix the sample in such a way that the shrinkage of the metal causes the formation of cracks;

b) to simulate the occurrence of phase separation cracks, a series of samples heated to temperatures slightly below a solidus temperature, and estimation of resistance to cracking is based on testing a number of samples to construct the curve of plasticity at high temperatures.

7.2.3 the Test load acting along the weld seam (varestraint test) and the test load acting across the weld (transvarestraint test)

The test load acting along and across the weld, is used for determining the resistance to formation of hot cracks by loading the sample simultaneously with the welding.

When the test load acting along the weld, the load is applied in the direction coinciding with the axis of the weld. The test enables the assessment of the occurrence of crystallization, phase separation cracks and cracks due to the fall in the ductility of the metal.

When the test load acting across the weld, the load is applied in the transverse relative to the axis of the weld direction. The test is used to evaluate the resistance to formation of crystallization cracks only. At a predetermined point in the welding operations are produced by loading the sample by bending around a mandrel of a particular shape. At the end of the test visually assess and measure cracking. Resistance to cracking is estimated according to the length of the cracks on the side subjected to tension.

7.2.4 Test adjustable flat tension specimen (controlled flat tensile test)

This test is carried out by stretching a single flat pattern that is stretched in the longitudinal direction in the test equipment that ensures the linear increase of loading rate. Controlled load is applied during execution of the weld. The speed of the stretching that causes hot cracking, is characterized as the critical speed of stretching and is used as a measure of resistance to hot cracking.

8 Application

The possible applications of the various tests are presented in tables 2 and 3.


Table 2 — Tests for resistance to hot cracking on samples with the natural stiffness and their application

Table 3 — Tests for resistance to hot cracking in the samples with the application of external loads and their application

App YES (reference). Information about the compliance of the referenced international standards reference the national standards of the Russian Federation

App YES
(reference)

Table YES.1