Hardness analysis: identifying the origin of a material defect in the laboratory

A hardness discrepancy can reveal a heat treatment anomaly, material heterogeneity, a weakened area, or a local transformation of the material. In the context of a failure-oriented hardness analysis, the laboratory compares sound areas and failed areas in order to highlight mechanical variations that may explain cracking, breakage, abnormal wear or loss of performance. This approach is particularly relevant for investigating a material defect on a metal part, coating or assembly subjected to service loads.

Hardness measurement is used to investigate brittle, ductile or fatigue failures, cracks, wear areas, deviations after heat treatment, and heterogeneities between the core and the surface. In practice, the laboratory carries out targeted comparisons between failed areas and reference areas to determine whether the observed hardness level is consistent with the intended use of the part. This approach usefully complements microscopic observation and failure analysis, notably through our SEM Analysis Laboratory.

Hardness is measured with a hardness tester, then interpreted alongside observations under an optical microscope and, if necessary, fractographic analysis. The goal is to link the measured value to the material’s actual metallurgical state: grain size, structure, gradients between surface and core, heat-affected zones or local transformations. This cross-reading makes it possible to more precisely qualify the origin of the material defect and avoid drawing conclusions based on a single measurement.

The laboratory supports manufacturers in understanding failures by combining hardness analysis, materials expertise and application-based interpretation. The goal is not only to measure, but to explain: compare critical areas, link the results to the manufacturing process, verify compliance with customer specifications and provide actionable information for technical decision-making, issue resolution or corrective action.

Interpreting a hardness measurement is not limited to a numerical value. It is part of a broader defect analysis approach combining fractographic examination, metallographic observation, chemical composition testing and surface characterization. Cross-referencing the results makes it possible to identify whether the origin of the material defect comes from an out-of-spec grade, an unsuitable treatment, corrosion, an inclusion, a surface defect or service loading. For additional investigations, discover our Material Laboratory Expertise.

A local variation in hardness may also be associated with corrosion, coating degradation, adhesion defects, particulate contamination or an inclusion. The laboratory can then combine hardness measurement with chemical and morphological analysis to verify the grade, confirm the nature of a surface treatment or characterize an internal defect. For the study of particles and internal heterogeneities, also see our page Inclusion Analysis Laboratory.

Depending on the case, the laboratory supplements the investigation with SEM-EDX, ICP, elemental analysis C/S, N/O, H, as well as surface techniques such as XPS, TOF-SIMS, AFM or roughness measurement. These methods make it possible to verify composition, identify oxidizing or corrosive agents, confirm the chemical nature of a surface treatment and assess coating uniformity. For a broader view of the investigative tools available, also consult Met Laboratory.

For industrial clients, the advantage lies in having complementary equipment on a single site: hardness tester, optical microscope, SEM-EDX, ICP-AES, XPS, TOF-SIMS, AFM and elemental analysis. The laboratory also provides support for R&D, process optimization, method development and training. It operates within a recognized quality framework, with COFRAC accreditation according to the available scope and recognition under the research tax credit scheme. Learn more about our Approved CIR Laboratory.

To start a defect analysis, it is necessary to define the context in which the defect appeared, the part’s function, the presumed material, service conditions, and the areas to compare. The laboratory can then propose a suitable analysis plan combining hardness, microstructure, composition, fractography, and surface examination. The deliverables aim to identify the origin of the material defect and guide corrective actions. To move forward with your case: send your parts, describe the nonconformity, compare the critical areas, confirm the material grade, verify the treatment, interpret the results, and secure your production.