🔩 Ultrasonic testing of steel castings with ferritic structure for highly stressed components (e.g. turbine housings) — detection of internal discontinuities by the pulse-echo technique in walls up to 600 mm and evaluation of planar and volumetric discontinuities according to severity levels assigned to the rim zone and the core zone, PN-EN 12680-2

Materials and NDT PN-EN 12680-2

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN 12680-2:2026-04, in full (our translation of the Polish text): “This document specifies the requirements for the ultrasonic testing of steel castings (with ferritic structure) for highly stressed components and the methods for determining internal discontinuities by the pulse-echo technique. Highly stressed means for example: — high material utilization (close to Rp0,2); — high static and cyclic load; — for fail-safe assessment, a fracture-mechanics assessment is required. An example of a highly stressed cast component is a turbine housing, subjected to combined high static, cyclic and thermal load. Guided by the need for performance or safety, purchasers determine whether components are highly stressed. For lower-stressed cast components for general purposes, EN 12680-1 applies. This document is applicable to the ultrasonic testing of steel castings with wall thicknesses up to and including 600 mm — usually after a heat treatment aimed at a fine-grained structure. For greater wall thicknesses, additional agreements are applied respecting the test procedure o[f] recording levels [sic in the card]. This document does not apply to austenitic steels and joint welds.” We read the text of the standard in the sample of SIST EN 12680-2:2026 (text of EN 12680-2:2025) from the cover through the table of contents, foreword and Clauses 1–3 up to and including 4.5. Outside the sample remain 4.6 (severity levels), the whole of Clause 5 (testing: material, equipment and coupling medium, sensitivity, surface preparation, range and sensitivity setting, recording limits, characterization and sizing, test report), the tables and figures with acceptance values, and Annexes A–D.

ACCORDING TO THE TEXT OF EN 12680-2:2025 (foreword, Clauses 1–4.5). The document was prepared by working group CEN/TC 190/WG 10 “Testing for inner discontinuities” of CEN/TC 190 “Foundry technology” (secretariat DIN); CEN approved it on 22 September 2025; it supersedes EN 12680-2:2003, and the significant changes are listed in Annex D (outside the sample). It is one of four European standards for ultrasonic testing of castings: Part 1 — steel castings for general purposes, Part 3 — spheroidal graphite cast iron castings, Part 4 — phased array ultrasonic testing of steel castings. Scope (1) — as in the card; highly stressed components are e.g. those with material utilization close to Rp0,2, high static and cyclic load, or a fail-safe assessment requiring a fracture-mechanics assessment, and the purchaser decides whether a component is highly stressed. References (2): EN 1370 (surface condition), EN ISO 2400 and EN ISO 7963 (blocks No. 1 and No. 2), EN ISO 5577 (vocabulary), EN ISO 16810 (general principles), EN ISO 16811 (sensitivity and range setting), EN ISO 16827 (characterization and sizing of discontinuities), EN ISO 22232-1, -2 and -3 (instrument, probes, combined equipment). Definitions (3): point-like discontinuity — dimensions not greater than the sound-beam width, extended — greater; planar — two measurable dimensions, volumetric — three; rim zone — 1/3 of the wall thickness from the surface, maximum 30 mm; special rim zone — outer zone with special requirements (e.g. machined surfaces, higher stresses, sealing surfaces); non-measurable dimension — smaller than the beam width, depending on probe size and frequency, in current practice below 3 mm; finishing welding; severity level — upper size limit for acceptable discontinuities, depending on the wall thickness zone. Order information (4.1): areas of the casting and number or percentage of castings to be tested, severity levels for the zones or areas (acceptance criteria), requirement for a written test procedure, additional requirements. Extent of testing (4.2): the agreed areas are covered by the best applicable technique insofar as the shape of the casting allows; for walls thicker than 600 mm severity levels, procedure and recording of results are agreed between manufacturer and customer. Zones (4.3): the wall section is divided into a core zone and rim zones (Figure 1), related to the dimensions of the casting ready for assembly; if the foundry does not know the final condition, the result applies to the condition “as delivered” (note — a discontinuity acceptable in the core of the raw casting can be shifted to the rim zone after final machining by the customer and become unacceptable); a single discontinuity extending into both zones is evaluated as rim zone. Maximum acceptable size of discontinuities (4.4): the purchaser specifies the acceptance level for planar and volumetric discontinuities in each zone and area; indications without measurable dimensions are acceptable in the core zone, and in special rim zones and at weld preparation ends their number is limited by the values of Table 1. Planar discontinuities (4.4.3.1): acceptance levels in Figure 2; in severity level 1 discontinuities exceeding a 3 mm FBH are not acceptable; the largest dimension in through-wall direction shall not exceed 10 % of the wall thickness, except discontinuities with a length of up to 10 mm, for which the limit is 25 % of the wall thickness or maximum 20 mm; the greatest distance at which discontinuities are evaluated as one discontinuity or as an area is 10 mm; for a discontinuity longer than 3 mm with a non-measurable through-wall dimension, this dimension is taken as 3 mm and the area is calculated with A = 3L (A in mm², L — length in mm); sizing of small planar discontinuities becomes more difficult with increasing beam path and beam diameter — it is normally applied to a rim zone of 30 mm and requires focused-beam probes, e.g. dual-transducer probes. Volumetric discontinuities (4.4.3.2): limiting sizes in Figure 3 (rim zone) and Figure 4 (core zone); in severity level 1 indications with measurable dimensions are not acceptable; discontinuity areas in through-wall direction — maximum 15 % of the rim zone thickness in the rim zone and 15 % of the wall thickness in the core zone; distance at which discontinuities are evaluated as one indication — 10 mm in the rim zone and 20 mm in the core zone; groups of individual discontinuities (reference code GIR, Table 4) are evaluated as separate areas when the distance to the neighbouring area is greater than the largest lateral dimension of each of them (example — Figure C.6); when radiographic and ultrasonic testing are combined and a discontinuity indicated by radiography lies in the core zone, it is acceptable at one lower severity level (e.g. 3 instead of 2 for radiography), unless otherwise agreed in the order — further in EN 1559-2. Personnel (4.5): testing is performed by qualified personnel, e.g. according to EN ISO 9712 or other equivalent recognized standards.

STATUS (catalogue cards as of 03.10.2026). The card of PN-EN 12680-2:2026-04 (English version) has no “Withdrawn” header: published 27-04-2026, 39 pages, price group R, Metallurgy Sector, KT 301 Foundry, ICS 77.140.80 and 77.040.20, “Introduces: EN 12680-2:2025 [IDT]”, “Replaces: PN-EN 12680-2:2005 - Polish version”. The card of PN-EN 12680-2:2005 (Polish version, published 26-07-2005, 36 pages) has a “Withdrawn” header with withdrawal date 27-04-2026, introduces EN 12680-2:2003 [IDT], replaces PN-EN 12680-2:2003 (English version) and is “Replaced by: PN-EN 12680-2:2026-04”; its scope referred to castings “after normalizing heat treatment”, the scope of the 2026-04 edition — to a treatment giving a fine-grained structure. The PKN search engine (query “PN-EN 12680-2”, 03.10.2026) shows the editions 2003 (EN), 2005 (PL) and 2026-04 (EN). European document: SIST EN 12680-2:2026 has the status “Published” in the iTeh catalogue (read 03.10.2026).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 03.10.2026). The number 12680-2 appears in 7 records at 7 laboratories: AB 197, AB 313, AB 608, AB 904, AB 1336, AB 1827, AB 1978. In the current scopes on the PCA website (read 03.10.2026, issues from 23.04.2025 to 02.09.2026) AB 197, AB 313, AB 1336 and AB 1827 give “PN-EN 12680-2:2005”, AB 1978 — “PN-EN 12680-2:2026-04”, AB 608 and AB 904 — the designation alone without year (both items in the flexible scope of accreditation, mark E). In all seven cells Part 1 (PN-EN 12680-1) stands next to it. The copy splits the AB 313 item so that the record of this standard has the object “600 mm”; in the PCA document it is one cell: steel castings with a thickness of up to 600 mm. The “Laboratories” tab (“PN-EN 12680-2”) shows all 7 laboratories; checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA scopes). “Internal discontinuities” (AB 197, AB 608, AB 1336, AB 1827) or “Discontinuities” (AB 313, AB 904, AB 1978), in all cases by the ultrasonic method. Object: steel castings (AB 608, AB 904), steel castings with a thickness of up to 600 mm (AB 313), castings (AB 1827, AB 1978), steel and cast iron castings (AB 1336), castings and products of cast iron, cast steel and non-ferrous metal alloys (AB 197). The items give no numerical ranges — except the thickness of 600 mm at AB 313, equal to the limit of the standard. Next to it stand Part 3 (spheroidal graphite cast iron castings — AB 197, AB 608, AB 1336, AB 1827, AB 1978) and PN-EN ISO 16810 (AB 904, AB 1827). Part 1 (PN-EN 12680-1) has a separate entry in the Knowledge Base.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Edition: four of the seven laboratories cite PN-EN 12680-2:2005, withdrawn on 27-04-2026 — the limiting values are read from the edition cited in the order; we do not have the changes between the editions (Annex D). Object: the standard applies to steel with ferritic structure, not to austenitic steels or joint welds (1) — the items “steel and cast iron castings” (AB 1336) and “castings of cast iron, cast steel and non-ferrous metal alloys” (AB 197) cover more than this part of the standard; spheroidal graphite cast iron has Part 3. Choice of part: the purchaser decides whether a component is highly stressed (1) — testing according to Part 1 does not replace Part 2. Condition of the casting: the zones relate to the dimensions of the casting ready for assembly; the result for a raw casting applies to the condition “as delivered”, and a discontinuity acceptable in the core can end up in the rim zone after machining (4.3). Evaluation: acceptability depends on the severity level assigned to the zone in the order (4.1 b), 4.4.1) — a result without severity level and zone does not tell whether the casting meets the requirements; a discontinuity extending into both zones is evaluated as rim zone (4.3). Sizing: a non-measurable through-wall dimension is taken as 3 mm (A = 3L), and small planar discontinuities in the rim zone are sized with focused-beam probes (4.4.3.1). Combination with radiography: the one-level relaxation applies only to discontinuities in the core zone and only unless the order states otherwise (4.4.3.2). Thickness: above 600 mm severity levels, procedure and recording must be agreed (4.2).

WHAT WE DO NOT GIVE. We do not have 4.6 or Clause 5 — so we give no requirements for the instrument, probes and coupling medium, surface preparation, range and sensitivity setting, recording limits, method of characterizing discontinuities or contents of the test report. We do not have Tables 1 and 4 or Figures 2–4 — so we give no numerical acceptable sizes for the individual severity levels other than those quoted above. We do not have Annexes A–D (resolution of detection of the equipment, beam diameters, types of indications, changes from the 2003 edition).

Method principle

The ultrasonic probe is moved over the surface of the casting and reflections from internal discontinuities are detected by the pulse-echo technique; discontinuities are classified as planar or volumetric, sized and compared with the acceptable sizes for the severity level that the order assigned to the rim zone or core zone of the casting wall.

Applications

• Steel castings with ferritic structure for highly stressed components, walls up to 600 mm (e.g. turbine housings — example from the scope of the standard); 7 laboratories in PCA scopes
• PCA items with steel castings, castings in general and steel and cast iron castings — always together with Part 1 (PN-EN 12680-1)
• Acceptance testing according to severity levels agreed in the order, also in combination with radiography (EN 1559-2)

Key parameters

Standard

Standard number

PN-EN 12680-2:2026-04 (wersja angielska; EN 12680-2:2025 IDT)

Title (PL)

Odlewnictwo — Badania ultradźwiękowe — Część 2: Odlewy staliwne na części pracujące pod wysokimi obciążeniami

Title (EN)

Founding — Ultrasonic testing — Part 2: Steel castings for highly stressed components

Step-by-step procedure

1. Order

   Establish the areas and number of castings to be tested, the severity levels for the zones, the requirement for a written procedure and additional requirements. PN-EN 12680-2:2026-04 current (PKN catalogue card as of 03.10.2026).

2. Zones

   Divide the wall into rim zones (1/3 of the thickness, maximum 30 mm) and core zone according to the dimensions of the casting ready for assembly; if the final condition is unknown — condition “as delivered”.

3. Testing

   Cover the agreed areas by the pulse-echo technique in the best possible arrangement; details of equipment, sensitivity and recording — Clause 5 (outside the sample).

4. Evaluation

   Classify discontinuities as planar or volumetric, size them (non-measurable dimension = 3 mm, A = 3L) and compare with the limits of the severity level of the zone; a discontinuity in both zones — as rim zone.

5. Result

   The casting meets or does not meet the severity level assigned to each zone; for walls > 600 mm — according to the agreements between manufacturer and customer.

Required equipment and apparatus

Health and safety (OHS)

• Testing is performed by qualified personnel, e.g. according to EN ISO 9712 (4.5)
• The result for a raw casting may not hold after machining — a discontinuity from the core can move into the rim zone and become unacceptable (note to 4.3)

Frequently asked questions