🔩 Longitudinal tensile test on weld metal in welded joints — round specimen of weld metal only, d0 = 10 mm (not less than 4 mm), according to ISO 6892-1; PN-EN ISO 5178

Materials and NDT PN-EN ISO 5178

Overview

WHAT THE STANDARD COVERS. ISO 5178:2019 (clause 1): specimen sizes and the procedure for the longitudinal tensile test on cylindrical specimens to determine the mechanical properties of the weld metal in a fusion welded joint. It applies to metallic materials in all product forms with joints made by any fusion welding process, provided the joint is large enough for cylindrical specimens with dimensions according to ISO 6892-1 to be cut from it. Unless otherwise specified, the general principles of ISO 6892-1 apply (the only normative reference; symbols also according to ISO 6892-1). It was prepared by committee ISO/TC 44 "Welding and allied processes", subcommittee SC 5 "Testing and inspection of welds". The second edition (2019) replaced ISO 5178:2001 as a technical revision: the reference was changed from ISO 6892 to ISO 6892-1, a mandatory clause 3 (without terms) was added, clauses 5 and 9 were revised. The "Scope" field of the PKN card of PN-EN ISO 5178:2019-04, in full (our translation): "This document specifies the sizes of test specimens and the procedure for the longitudinal tensile test of cylindrical test specimens in order to determine the mechanical properties of the weld metal in a welded joint. This document applies to metallic materials in all product forms, with welds made by any welding process, having joint dimensions sufficient to obtain cylindrical test specimens with dimensions in accordance with ISO 6892-1. Unless otherwise specified, the general principles laid down in ISO 6892-1 apply to the individual clauses of this document." The card says "weld metal" (metal spoiny) and "by any welding process", whereas the text of the standard speaks of any fusion welding process.

PROCEDURE (ISO 5178:2019, clauses 5–9 and Annex A — full text of the standard read). Principle: an increasing tensile force is applied continuously until fracture of a cylindrical specimen taken longitudinally from the weld metal of the joint; the test is carried out at room temperature 10–35 °C unless otherwise agreed, and under controlled conditions at 23 ± 5 °C. • Location (6.1, 6.5): the specimen is taken longitudinally from the joint of the product or from a test piece; after machining the parallel length shall consist ONLY of weld metal (Figures 1 and 2). To locate the specimen correctly, the cross-section of the joint at both ends may be macro-etched. Unless otherwise specified in the application standard, the specimen is taken from the centre of the weld metal; when not from mid-thickness — the distance t1 from the surface is recorded; for very thick joints or joints welded from both sides several specimens may be taken at different depths (the distances t1 and t2 of each are recorded). • Marking (6.2): the test piece is marked so that its position in the product or joint is known, and each specimen — so that its position in the test piece is known. • Heat treatment and ageing (6.3): no heat treatment of the joint or specimen unless required or permitted by the application standard; details of the treatment to be reported; with natural ageing of aluminium alloys the time between welding and testing is recorded. The note in the text of the standard reads: "The presence of hydrogen in ferrous weld metals can adversely affect the test results and suitable hydrogen release treatment." — the presence of hydrogen in ferrous weld metal can adversely affect the results (sentence broken off in the text of the standard; we quote it as it stands). • Cutting (6.4): mechanical and thermal processes shall in no way alter the properties of the specimen. Steel: shearing excluded for thicknesses above 8 mm; with thermal cutting or another process affecting the cut surface — at a distance of at least 8 mm from the final surface of the parallel length; thermal cutting is not carried out parallel to the original surface of the plate. Other metals: no shearing or thermal cutting, only machining (e.g. sawing, turning). • Dimensions (6.6, 6.7): circular cross-section, dimensions as functions of the diameter d0 of the parallel length according to ISO 6892-1; nominal diameter d0 = 10 mm, and when this is not possible — as large as possible, not less than 4 mm (the actual one is recorded in the report); grips compatible with the machine; tolerances according to ISO 6892-1; avoid strain hardening and excessive heating. • Test and results (7, 8): gradual and continuous loading according to ISO 6892-1; results are determined according to ISO 6892-1. After fracture the fracture surfaces are examined and imperfections that may have adversely affected the test are recorded — type, size and number; "fish eyes" are recorded, and only their central area is considered an imperfection. • Test report (9, Annex A): in addition to the data according to ISO 6892-1 — reference to ISO 5178, location of the specimen (sketch, if needed), test temperature if different from ambient, type and dimensions of imperfections, diameter d0. Example Table A.1: Fp, Fm, Rp, Rm, L0, A, Z, temperature, remarks (e.g. appearance of the fracture); Rp and Fp may be replaced by the upper and lower yield strength or the proof strength at total extension, depending on the requirements.

STATUS (state of the PKN card on 10.10.2026). The card of PN-EN ISO 5178:2019-04 (English version) carries no withdrawal label: title "Badania niszczące spoin materiałów metalowych -- Próba rozciągania wzdłużnego metalu spoiny w połączeniach spawanych" (Destructive tests on welds in metallic materials — Longitudinal tensile test on weld metal in welded joints; our translation), publication 16-04-2019, 16 pages, Sector of Metallurgy, KT 165 Welding and Allied Processes, "Replaces: PN-EN ISO 5178:2011/Ap1:2016-06 - English version, PN-EN ISO 5178:2011 - English version", "Introduces: EN ISO 5178:2019 [IDT], ISO 5178:2019 [IDT]", ICS 25.160.40. The standard has no Polish language version: the PKN search engine, query "ISO 5178" (10.10.2026), shows with this number only the cards PN-EN ISO 5178:2011 and PN-EN ISO 5178:2019-04, both in the English version (the other results are different standards, e.g. PN-EN ISO 25178 and PN-ISO 15178).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database of 10.10.2026 and current PCA documents read on 10.10.2026). The number 5178 appears in 10 records at 8 laboratories: AB 001 (2 records), AB 024, AB 025, AB 042, AB 099, AB 1505, AB 1623 and AB 1700 (2); the standard is present in all 8 current PCA documents, no entry is suspended. Form — everywhere "PN-EN ISO 5178:2019-04", usually in one cell with PN-EN ISO 6892-1:2020-05 (method B) and often with PN-EN ISO 4136:2022-12 (transverse tensile test of joints). The "Laboratories" tab ("PN-EN ISO 5178") shows 7 laboratories; AB 024 is outside it because in its entry the number stands at the end of the string "PN-EN ISO 6892-1:2020-05 Metoda B PN-88/M-69710 PN-EN ISO 4136:2022-12 PN-EN ISO 5178:2019-04". Discrepancy between the copy and PCA: in the database copy the standard of AB 042 is assigned to "susceptibility to plastic deformation — bend tests", whereas in the PCA document it stands with the tensile mechanical properties (base material for joining and weld metal; with PN-EN ISO 6892-1:2020-05 and PN-EN ISO 15630-1:2019-04 clause 5; force range up to 1000 kN).

WHAT THE LABORATORIES TEST (copy and PCA documents). Subject: welded joints (AB 025 — also irradiated, AB 099, AB 1505, AB 1623), metals and welded joints (AB 001), weld metal (AB 1700), base material for joining and weld metal (AB 042), metal products (AB 024). Quantities: yield strength Re and proof strength Rp, tensile strength Rm, elongation A, reduction of area Z, force Fm (AB 025 and AB 1505 only Fm and Rm, AB 099 — Rm and A); AB 001 adds "rupture stress"; technique — tensile test at room temperature.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — parallel length not of weld metal only: if the heat-affected zone or parent material falls within the gauge part, the result describes a mixture, not the weld metal — which is why the standard allows the cross-section at the specimen ends to be etched before machining. Second — hydrogen: in steel weld metal the presence of hydrogen can adversely affect the results (note to 6.3); heat treatment is permitted only when required or permitted by the application standard, and it has to be recorded. Third — smaller diameter: with d0 below 10 mm (at least 4 mm) the elongation depends on the gauge length according to ISO 6892-1 — a comparison with a requirement without stating d0 is incomplete. Fourth — fracture: imperfections on the fracture surface (pores, inclusions, "fish eyes") have to be recorded, because they may have lowered the result; "fish eyes" count as an imperfection only in their central part. Fifth — this standard is the LONGITUDINAL test of weld metal; the transverse test of a joint is PN-EN ISO 4136 (a separate entry in this database).

WHAT WE DO NOT GIVE. Standard read in full; we do not give the requirements of ISO 6892-1 (dimensions of proportional specimens, strain rates, the way Rp and A are determined), to which it refers, or requirements for weld metal properties — these are in the standards for filler materials and in welding procedure specifications.

Method principle

A cylindrical specimen is cut from the welded joint along the weld, the parallel length of which after machining consists only of weld metal (d0 = 10 mm, if necessary at least 4 mm), and is pulled by an increasing force applied continuously until fracture, at 10–35 °C (under controlled conditions 23 ± 5 °C), according to ISO 6892-1; the results (Rp/Re, Rm, A, Z) are determined according to ISO 6892-1, and the fracture is assessed for imperfections (ISO 5178:2019, clauses 5–8).

Applications

• Weld metal in joints of metals welded by any fusion process, if the size of the joint allows cylindrical specimens according to ISO 6892-1 to be cut (ISO 5178:2019, clause 1)
• Testing of weld metal for the classification of filler materials (Figure 2a: all-weld-metal specimen) and of joints welded from one and both sides
• In the accreditation scopes: 8 laboratories; usually in one entry with PN-EN ISO 6892-1 and PN-EN ISO 4136

Key parameters

Standard

Standard number

PN-EN ISO 5178:2019-04 (wersja angielska; wprowadza EN ISO 5178:2019 [IDT] oraz ISO 5178:2019 [IDT])

Title (PL)

Badania niszczące spoin materiałów metalowych — Próba rozciągania wzdłużnego metalu spoiny w połączeniach spawanych

Title (EN)

Destructive tests on welds in metallic materials — Longitudinal tensile test on weld metal in fusion welded joints

Step-by-step procedure

1. Marking and location

   Mark the test piece and the position of each specimen; if necessary macro-etch the cross-section of the joint at the ends so that the parallel length consists only of weld metal; by default the centre of the weld metal, at mid-thickness (otherwise record t1, t2).

2. Cutting

   Steel: no shearing above 8 mm; thermal cutting at least 8 mm from the final parallel length, not parallel to the plate surface. Other metals: only machining.

3. Machining the specimen

   Round specimen, d0 = 10 mm (minimum 4 mm), dimensions and tolerances according to ISO 6892-1; without strain hardening and overheating. Heat treatment only when required by the application standard — record it.

4. Tensile test

   Load gradually and continuously according to ISO 6892-1 until fracture, at 10–35 °C (controlled: 23 ± 5 °C).

   🌡 Temperature: 10–35 °C (23 ± 5 °C)

5. Results and fracture

   Rp/Re, Rm, A, Z according to ISO 6892-1; examine the fracture surfaces and record imperfections (type, size, number; "fish eyes" — central area).

6. Test report

   Reference to ISO 5178, location of the specimen, temperature, imperfections, d0 (example — Annex A). PN-EN ISO 5178:2019-04 current (state of the PKN card on 10.10.2026).

Required equipment and apparatus

Health and safety (OHS)

• Fracture of the specimen releases elastic energy — guards of the testing machine, eye protection
• Thermal cutting and machining — eye and respiratory protection, machine guards
• NOTE ON SUBSTANCE: parallel length of weld metal only; without this the result does not describe the weld metal

Frequently asked questions