A stamped bracket splits on the press line. A starter motor stops turning over. A hydraulic hose assembly weeps at its fitting during a pressure check. Each failure leaves physical evidence on the part itself, and failure analysis is the discipline that reads it. ASM International describes its reference volume on the subject as a resource for analysts and engineers working to identify root causes and prevent repeat failures.
Manufacturers bring these questions to outside labs regularly. One needs thousands of hose assemblies proof-tested before shipment. Another watches a pipe weldment lose pressure on the test stand. A third holds a bearing steel part of uncertain grade. Behind each project sits the same question: What does the part itself reveal about how it performs, or why it did not?
Key Takeaways
- Failure analysis combines visual examination, nondestructive testing, chemical analysis, fractography, metallography, and mechanical testing to reach a root cause, as reflected in the structure of ASM Handbook, Volume 11.
- ASTM E1003 covers hydrostatic leak testing with a liquid and limits the practice to leakage indications of 1 × 10⁻⁴ std cm³/s or larger.
- ASTM E2930 covers pressure decay leak testing of rigid vessels and excludes deformable ones.
- ISO 1402:2021 and SAE J343 cover hydrostatic and performance testing of rubber, plastics, and hydraulic hose assemblies.
- ASTM E415 covers spark emission analysis of 21 elements in carbon and low-alloy steels, a common route to steel identification.
- NIST released the fourth edition of its fractography guide for ceramics and glasses in 2026; it addresses brittle-material failures such as cracked ceramic parts.
- Labs that handle fracture samples ask requesters to keep fracture faces untouched, avoid heat near the fracture, and send both mating halves.
What Is Failure Analysis?
Failure analysis is a structured investigation into why a component, assembly, or material stopped performing as designed. The goal goes beyond naming the fracture or leak. Analysts work to identify the root cause and whether it lies in material, design, manufacturing, assembly, or service conditions.
The 2021 edition of ASM Handbook, Volume 11, Failure Analysis and Prevention, shows how the field organizes the work. A practice division covers the investigation process, nondestructive evaluation, bulk and microscale composition analysis, microfractography and metallography, stress analysis, and finite element modeling. Later divisions address fatigue and fracture, environmental and corrosion-related failures, wear, and distortion.
A typical investigation draws on those tools in a broadly consistent order, moving from least to most destructive:
- Background and service history: Analysts gather drawings, material specifications, operating loads, environment, and time in service.
- Visual examination and photography: Low-magnification documentation records the as-received condition before anything alters it.
- Nondestructive testing: Methods such as radiography, ultrasonics, dye penetrant, and magnetic particle inspection locate cracks and internal defects.
- Chemical analysis: Bulk composition confirms whether the material matches its specification.
- Fractography: Stereo and scanning electron microscopy (SEM) examine the fracture surface to locate the origin and identify the fracture mechanism.
- Metallography: Sectioning, polishing, and etching reveal microstructure, heat treatment condition, inclusions, and coating or case depth.
- Mechanical and hardness testing: Results show whether strength and hardness meet the specification.
- Analysis and reporting: Investigators reconcile the evidence, test competing hypotheses, and document the most probable root cause.
Order matters because many steps consume evidence. Sectioning destroys a fracture face, and cleaning can remove corrosion products that point to the failure mechanism. Contract Laboratory’s overview of metallurgical testing covers several of these methods in more depth.
Which Laboratory Methods Do Failure Investigations Use?
No single test identifies a root cause. Each method answers a narrower question, and analysts combine the answers. The table below maps common methods to what they reveal and to standards that frequently apply.
| Method | What it reveals | Standards and references often cited |
|---|---|---|
| Visual and stereo microscopy | Fracture origin, crack path, deformation, corrosion, and wear patterns | ASM Handbook, Vol. 11 |
| SEM fractography | Fracture mechanism at high magnification, such as fatigue striations, dimples, or cleavage | ASM Handbook, Vol. 11; NIST SP 960-16 for ceramics and glasses |
| Metallography | Microstructure, heat treatment response, inclusions, decarburization, and case depth | ASM Handbook, Vol. 11 |
| Hardness and microhardness | Bulk hardness, hardness gradients, and case or weld zone variation | ASTM E384 (Knoop and Vickers microindentation) |
| Spark optical emission spectrometry | Alloying and residual element content of carbon and low-alloy steels | ASTM E415 |
| Wear testing | Relative wear and friction of material pairs under sliding | ASTM G99 (pin-on-disk or ball-on-disk) |
1. Hardness and Steel Identification
Hardness testing often serves as a fast check against a drawing callout. ASTM E384-22 covers Knoop and Vickers microindentation at test forces from 1 to 1,000 gf. The standard notes that microindentation reveals local hardness variation, so a single reading may not represent bulk hardness. It also states that the elongated Knoop indenter suits measurements of hardness change over very small distances, such as case depth profiles.
Steel identification usually pairs hardness with chemistry. ASTM E415-21 covers simultaneous determination of 21 alloying and residual elements in carbon and low-alloy steels by spark atomic emission spectrometry. The ASTM describes the method as intended primarily to check compliance with compositional specifications. Investigators compare those results against the grade the drawing or purchase order specifies. Contract Laboratory’s metallurgical analysis category lists related requests and providers.
2. Fractography of Metals and Ceramics
Fractography reads the fracture surface itself. In metals, surface features help separate fatigue, ductile overload, brittle fracture, and environmentally assisted cracking. Brittle materials need a different eye. The NIST Recommended Practice Guide: Fractography of Ceramics and Glasses, now in its fourth edition (2026), states that fractography can identify the cause of failure and provide quantitative information about loading conditions. NIST offers the guide free of charge.
3. Wear Testing for Comparative Studies
Wear complaints often call for a comparison rather than a single result, for example, ranking two bushing materials. ASTM G99-23 covers wear and friction testing with a pin-on-disk or ball-on-disk apparatus. ASTM’s significance statement for G99 notes that wear depends on load, speed, sliding distance, environment, and material properties. It also states that the method does not duplicate all service conditions, so its value lies in ranking material combinations.
How Do Hydrostatic, Pressure Decay, and Leak Tests Differ?
Pressure and leak tests serve two purposes in failure work. They screen production parts for defects, and they reproduce a field leak so analysts can locate it. The choice of method depends on the test medium, the part’s stiffness, and the leak rate.
| Standard | Scope | Notable limits or requirements |
|---|---|---|
| ASTM E1003, Hydrostatic Leak Testing | Leak testing of piping, valves, and containers pressurized internally with a liquid | Limited to leakage indications of 4.5 × 10⁻⁹ mol/s (1 × 10⁻⁴ std cm³/s) or larger; not sensitive enough for toxic or explosive gas service |
| ASTM E2930-26, Pressure Decay Leak Test Method | Leakage rate of a vessel under positive pressure, calculated from pressure, temperature, and time with the ideal gas law | Does not apply to deformable vessels |
| ISO 1402:2021, Hydrostatic Testing of Hoses | Hydrostatic test methods for rubber and plastics hoses and hose assemblies, including dimensional stability | ISO completed a systematic review of the 2021 edition in June 2026 |
| SAE J343, Tests for SAE 100R Hydraulic Hose | Test methods for SAE 100R series hydraulic hose and assemblies with attached end fittings | Performance criteria sit in the hose specifications of SAE J517; SAE reaffirmed J343 in October 2023 |
Hydrostatic Testing
Hydrostatic testing fills a part with liquid, usually water, and pressurizes it. ASTM E1003 applies to welded or fitted sections that analysts can seal at the ends and that are designed for internal pressure. ASTM lists quality control and field inspection of piping, pipelines, valves, and liquid containers as typical uses. For hose assemblies, ISO 1402:2021 and SAE J343 supply hose-specific procedures. The hose assembly request on the Contract Laboratory board illustrates the scale this work can reach: 3,995 samples in 3-inch and 4-inch inside diameters.
Pressure Decay Testing
Pressure decay testing pressurizes a sealed part with gas, isolates it, and tracks the pressure drop over time. The practice calculates mass loss from measured pressure, temperature, and time, and it excludes deformable vessels. That exclusion matters: A flexing part changes volume under pressure, which a rigid-vessel calculation reads as leakage. Rigid parts such as pipe weldments fit the method more naturally than hose.
ASTM’s significance and use section for E2930 states that a test should keep total pressure change under 10% of the starting pressure. The 2013 edition adds that when a test certifies a maximum leakage rate, equipment and test duration should give resolution ten times finer and accuracy four times finer than the specification.
Test pressure belongs in the specification. The E2930 standard states that leak test specifications should name the vessel test pressure or differential pressure, and that tests without one should use a safe pressure consistent with applicable safety standards. Contract Laboratory’s mechanical and structural testing category lists providers for both test types.
What Failure Modes Do Labs Most Often Investigate?
ASM Handbook, Volume 11, groups failures into four broad families after its practice and tools divisions: Fatigue and fracture, environmental and corrosion-related failures, wear, and distortion. Most investigations begin by placing a failure in one of these families, then narrow toward a specific mechanism and cause.
| Failure family | Typical field symptom | Lab techniques that commonly apply |
|---|---|---|
| Fatigue | Crack that grows over many load cycles before final fracture | Fractography (stereo and SEM), metallography, stress analysis |
| Overload fracture | Sudden ductile or brittle break under a single high load | Fractography, hardness, tensile testing, chemistry |
| Environmental and corrosion-related | Pitting, stress corrosion cracking, or hydrogen embrittlement | SEM with energy-dispersive spectroscopy, metallography, corrosion product analysis |
| Wear | Material loss, scoring, or galling at contact surfaces | Surface profilometry, SEM, comparative wear testing such as ASTM G99 |
| Distortion | Permanent deformation, warping, or dimensional change | Dimensional inspection, hardness, heat treatment review |
Forming Splits in Stamped Parts
Some failures happen before a part ever enters service. In sheet metal stamping, a split occurs when the metal tears during forming. The cause can lie in the material, the tooling, or the process, and those factors rarely act alone. A 2026 peer-reviewed study in Materials ran a factorial experiment on a seven-station progressive die. Die bottom dead center depth and punch-die clearance had the largest effect on part geometry, and the process variables acted interactively rather than independently. SEM examination linked worn tooling and inadequate lubrication to microcracking and near-surface damage. The study measured bend angles and surface integrity rather than splits, but its literature review also identifies lot-to-lot variation in coil mechanical properties as a documented source of quality drift. A split investigation, therefore, often combines chemistry, hardness, and microstructure with a review of formability data, die condition, and press settings.
Hydrogen Embrittlement and Corrosion
Environmentally assisted failures can resemble ordinary overload at first glance. The ASM Handbook, Volume 11: Failure Analysis and Prevention, devotes a full division to environmental and corrosion-related failures, separate from fatigue and fracture. Mechanisms such as hydrogen embrittlement and stress corrosion cracking often require SEM fractography and chemical analysis of surface deposits to tell apart. Contract Laboratory’s microscopy and imaging category covers SEM and related providers.
What Do Labs Need and Requesters Look For?
A failure investigation depends on the evidence that reaches the lab and the context that comes with it. Lab submission guidance and accreditation requirements describe both sides of that exchange.
1. Sample Handling and Background Information
Two practices from ASTM Committee E30 address evidence handling when a failure may lead to litigation. ASTM E1188-23 covers standard practice for collection and preservation of information and physical items, or evidence, for analysis by a technical investigator. ASTM E860-22 sets procedures to document the nature, state, or condition of evidence items. It also describes actions required before testing, disassembly, or other steps that would alter the evidence and limit further examination. The same principle extends to routine investigations: Cleaning, heating, or cutting near a fracture can erase the features analysts rely on.
Background shapes the scope: A request that names the material specification, drawing, service life, load history, and the number of failed versus unfailed parts lets a lab propose a targeted test plan rather than a broad survey.
2. Accreditation and Reporting
Requesters frequently ask for ISO/IEC 17025 accreditation, and board activity reflects that. The ISO/IEC 17025:2017 sets requirements for the competence, impartiality, and consistent operation of testing and calibration laboratories. Accreditation applies to a defined scope, so a lab’s certificate lists the specific methods it covers.
Scope matters for pressure work too. A lab accredited for metallography may not hold accreditation for hydrostatic or pressure decay testing. Requesters can compare each provider’s scope against the standards their specification names, whether that is ASTM E1003, ASTM E2930, ISO 1402, or SAE J343.
For Labs and CROs
Failure analysis requests span materials, industries, and sample counts. Requests posted to Contract Laboratory have ranged from a single stamped metal part with a split to the 3,995-unit hose assembly program. Labs with fractography, metallography, and pressure testing capability can review open projects in the Lab Requests section, where the forensic investigations and testing and metallurgical analysis categories collect related work.
Connect on Contract Laboratory
Contract Laboratory connects manufacturers, engineers, and researchers with laboratories that perform failure analysis, fractography, metallography, hardness testing, and hydrostatic and leak testing.
- Submit a Request to describe a failed part, a test program, or a standard you need performed.
- View Requests to see open projects, including pressure and materials testing work.
- Register Your Lab to receive matched requests in your areas of capability.
This article was created with the assistance of Generative AI and has undergone editorial review before publishing.
Sources and Further Reading
- ASM International. ASM Handbook, Volume 11: Failure Analysis and Prevention, product and contents page. 2021 edition.
- ASTM International. E1003, Standard Practice for Hydrostatic Leak Testing.
- ASTM International. E2930-26, Standard Practice for Pressure Decay Leak Test Method, ASTM store and ANSI Webstore listing.
- ASTM International. E2930-13(2021), catalog listing with significance text.
- ASTM International. E384-22, Standard Test Method for Microindentation Hardness of Materials.
- ASTM International. E415-21, Analysis of Carbon and Low-Alloy Steel by Spark Atomic Emission Spectrometry.
- ASTM International. G99-23, Wear and Friction Testing with a Pin-on-Disk or Ball-on-Disk Apparatus.
- ISO. ISO 1402:2021, Rubber and Plastics Hoses and Hose Assemblies, Hydrostatic Testing (national standards body record).
- ISO. ISO/IEC 17025:2017, General Requirements for the Competence of Testing and Calibration Laboratories.
- SAE International. J343_202310, Test and Test Procedures for SAE 100R Series Hydraulic Hose and Hose Assemblies.
- Quinn, G. NIST Recommended Practice Guide: Fractography of Ceramics and Glasses, 4th Edition. NIST SP 960-16e4, 2026.
- Skardžius, J., & Gargasas, J. (2026). Impact of Process Variables on Part Quality in Progressive Stamping. Materials, 19(2), 312. https://doi.org/10.3390/ma19020312
Frequently Asked Questions (FAQs)
Failure analysis covers the technical examination of the failed part: fractography, metallography, chemistry, and testing. Root cause analysis uses those findings to identify the underlying design, material, process, or service condition that produced the failure. In practice, labs often deliver both in one report.
Fractography examines fracture surfaces to locate the crack origin and identify the fracture mechanism. Analysts use stereo microscopes and scanning electron microscopes. For brittle materials, the NIST fractography guide states that the technique can also yield quantitative information about loading conditions.
ASTM E2930-26 states that its pressure decay method does not apply to deformable vessels. Hose assemblies typically fall under hose-specific standards such as ISO 1402:2021 and SAE J343.
The ASTM E1003 standard limits its procedures to leakage indications of 1 × 10⁻⁴ std cm³/s or larger. The ASTM also states that the practice lacks the sensitivity for components expected to hold toxic or explosive gas under pressure.
Labs typically combine chemical analysis with hardness and microstructure. ASTM E415 covers spark atomic emission analysis of 21 elements in carbon and low-alloy steels. Hardness methods, such as ASTM E384, add strength and heat treatment information.
Lab guidance commonly asks for both halves of a fracture, an untouched and unheated fracture surface, drawings and material specifications, service history, and an unfailed reference part when available.
Requirements depend on the purchaser, the industry, and any applicable regulation. ISO/IEC 17025:2017 sets competence, impartiality, and consistent operation requirements, and accreditation bodies use it to assess labs. Accreditation covers a listed scope of methods rather than every service a lab offers.