--- type: "WebPage" title: "ISO 4935 Testing" description: "Do you need to perform sulfur determination according to ISO 4935 ? Securing metallic materials for the ASD sector with ISO 4935 In the Aerospace, Space, and Defense (ASD) sectors, the purity of ferrous alloys is a safety imperative. Sulfur..." resource: "https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/iso-4935-analysis/" tags: ["EN", "pll_698c40f2cb60f"] timestamp: "2026-04-22T13:08:23Z" published: "2026-02-11T08:47:19Z" language: "en" author: "Filab" --- # ISO 4935 Testing ## Do you need to perform sulfur determination according to ISO 4935 ? ### Securing metallic materials for the ASD sector with ISO 4935 In the [Aerospace](https://filab.fr/en/sectors-of-activity/laboratory-analysis-aeronautics-aerospace.md), [Space](https://filab.fr/en/sectors-of-activity/laboratory-analysis-aeronautics-aerospace.md), and [Defense](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector.md) (ASD) sectors, the purity of [ferrous alloys](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/iron-alloys-analysis-at-filab-laboratory.md) is a safety imperative. Sulfur content is a parameter monitored very closely: excessive concentration can lead to hot shortness and severely impair the integrity of your **essential parts.** [ISO 4935](https://www.iso.org/fr/standard/10949.html) specifies a method for the determination of [sulfur](https://filab.fr/en/our-services/our-analysis-services/halogen-analysis-laboratory/laboratory-sulfur-determination.md) in [steels](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-of-analysis-and-expertise-of-steels.md) and [cast irons](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-analysis-cast-iron.md) by infrared absorption spectrometry after combustion in an induction furnace. This method is the benchmark for guaranteeing reliable and repeatable measurements, essential for validating your[metallic grades](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/control-of-alloys-and-grades-in-the-laboratory.md). At **FILAB**, we support manufacturers in the ASD supply chain with the characterization and control of their materials according to ISO 4935. Our goal is clear: to ensure the reliability of your technical and industrial decisions. ### ISO 4935: a key challenge for steel and cast iron integrity ### Sulfur analysis by combustion according to ISO 4935 The ISO 4935 standard relies on the total oxidation of the sample. The sulfur present in the metal matrix is converted into sulfur dioxide (SO2), which is then quantified with very high sensitivity by infrared detectors. It is specifically used to: - **Precisely measure** sulfur content, even at trace levels. - **Check compliance** of stainless steels, alloy steels, and cast irons. - **Verify the absence of sulfur segregations** that could weaken structures during forging or welding. In the Aerospace and Defense industries, mastering sulfur according to ISO 4935 has a direct impact on: - **Hot ductility** during forming processes. - **Resistance to pitting corrosion** (limiting Manganese Sulfide inclusions). - **In-service behavior** of **strategic components** subjected to high tensile stress. ## FILAB, a laboratory tailored to Aerospace & Defense requirements ### An analytical park dedicated to ISO 4935 testing Analysis according to ISO 4935 requires perfect mastery of high-temperature combustion. To meet these demands,**FILAB** provides its clients with state-of-the-art equipment : [### OES](https://filab.fr/en/our-technical-resources/laboratory-analysis-oes-alloys.md) [### C/S Elemental Analyzers](https://filab.fr/en/our-technical-resources/chons-laboratory-analysis.md) ### Dedicated material expertise services At **FILAB**, ISO 4935 analysis is part of a comprehensive material characterization approach. We do not just produce results: we help you understand the influence of sulfur on your alloy properties. Our teams work on : Carbon, [stainless](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-analysis-of-your-stainless-steels-according-to-nf-en-10088-standards.md), and [refractory steels](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/laboratory-for-analysis-and-characterization-of-refractory-alloys.md) [Failure](https://filab.fr/en/our-services/our-expertise-services/laboratory-analysis-failures.md) analysis (hot [cracking](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-material-testing/crack-analysis-laboratory/)) High-quality cast irons ### Why Choose FILAB ? - **45 years** of recognized expertise in analysis and materials science - **Dual competence:** Chemistry / Materials - Specializing in **metallic alloys**and **critical applications** - **Customer qualification**: Safran, Dassault Aviation, and Framatome - **ISO 17025 Accreditation** regarding metallic alloys [Discover our accreditations](https://filab.fr/en/about-us/accreditations-en.md) Discover our metallurgical expertise ## Analysis of Iron, Aluminium, Molybdenum, Copper, Tin, Chromium, Titanium, Lead, Nickel, Zinc [Learn more](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory.md) ### Our analytical services based on ISO and ASTM standards for the ASD sector [Analysis according to ASTM E3061 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e3061.md) [Analysis according to ASTM E1086 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e1086.md) [Analysis according to ASTM E1019 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e1019.md) [Analysis according to ISO 8287 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/iso-8287-testing.md) [Analysis according to ASTM B213 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/analysis-astm-b213.md) [Analysis according to ASTM B964 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-b964.md) [Analysis according to ISO 12154 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-iso-12154.md) [Analysis according to ASTM E1868 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e1868.md) [Analysis according to ASTM E1409 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-e1409-analysis.md) [Analysis according to ASTM E415 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e415.md) [Analysis according to ASTM E1251 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-e1086.md) [Analysis according to ISO 15350 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/iso-15350-testing.md) [Analysis according to ASTM E1941 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/analysis-astm-e1941.md) [Analysis according to ISO 4490 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/iso-4490-analysis.md) [Analysis according to ASTM B527 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-b527.md) [Analysis according to ASTM B923 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-b923.md) [Analysis according to ASTM A269 standard](https://filab.fr/en/our-services/our-analysis-services/metallurgical-analysis-laboratory/astm-analysis-a269.md) ### Our analytical services in accordance with MIL requirements for the ASD sector [Analysis according to MIL-T-9047 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-t-9047-analysis.md) [Analysis according to MIL-A-6088 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-a-6088-analysis.md) [Analysis according to MIL-DTL-14067 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-dtl-14067-analysis.md) [Analysis according to MIL-DTL-5002 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-dtl-5002-analysis.md) [Analysis according to MIL-A-22771 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-a-22771-analysis.md) [Analysis according to MIL-S-22499 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-s-22499-analysis.md) [Analysis according to MIL-P-83348 requirement](https://filab.fr/en/sectors-of-activity/laboratory-analyses-tests-defense-security-sector/mil-p-83348-analysis.md) ### Our additional metallographic analysis [Micrographic analysis](https://filab.fr/nos-prestations/analyse/laboratoire-analyses-metallurgiques/laboratoire-examen-micrographique.md) [Failure analysis](https://filab.fr/nos-prestations/expertise/labo-analyse-etude-de-defaillance.md) [Chemical composition analysis](https://filab.fr/nos-prestations/analyse/laboratoire-analyses-metallurgiques/laboratoire-analyse-alliage-metallique.md) [Metallurgical analysis](https://filab.fr/nos-prestations/analyse/laboratoire-analyses-metallurgiques.md) [Metallographic analysis](https://filab.fr/nos-prestations/analyse/laboratoire-analyses-metallurgiques/caracterisation-par-coupe-metallographique.md) [Elemental analysis](https://filab.fr/en/our-services/our-analysis-services/chemical-analysis-laboratory/laboratory-elemental-analysis.md) [Analysis of metallic alloys](https://filab.fr/en/analysis-of-metallic-alloys-in-the-laboratory.md) ### Accreditation This [Nadcap accreditation](https://filab.fr/en/about-us/accreditations-en/materials-testing-nadcap-laboratory.md) notably covers: ✔️ Chemical analysis (ICP-OES) of critical metallic alloys (Al, Fe, Ni, Ti) ✔️ Metallography An international recognition that confirms our commitment to quality and reliability for the most demanding applications, particularly in the aerospace sector. ![](https://filab.fr/wp-content/uploads/2026/04/PNG-bleu-e1775737225243-1024x446.png) [Explore our accreditations](https://filab.fr/en/about-us/accreditations-en.md) ## FAQ Why choose ISO 4935 over Spark Analysis (OES)? Optical Emission Spectrometry (OES) is fast for routine control, but ISO 4935 by combustion is the **reference method for sulfur**. It allows for the analysis of the sample's **total volume**, offering significantly higher precision, especially for **ultra-low sulfur steels**. What content ranges are covered by this standard? ISO 4935 is effective for sulfur contents ranging from **0.002% to approximately 0.10%**, thus covering almost all industrial needs in the ASD sector. How is the sample prepared? The sample is taken in the form of **chips** or small solid pieces. It undergoes **rigorous degreasing** to remove any trace of cutting oil, ensuring that the measured sulfur comes exclusively from the metallic material. Can Carbon determination be performed simultaneously? Yes, the equipment used for ISO 4935 generally allows for **Carbon determination** (according to ISO 15350) during the same combustion cycle, optimizing both lead times and costs.