What Was the Client’s Objective?
The client wanted to check the quality of a steel part. The goal was to measure the residual stress in the cladding and determine whether the coating had separated or cracked.
The client requested the following:
1) Residual stress measurement using the hole-drilling method.
2) Inspection of the cladding for edge delamination and cracking.
3) Additional edge preparation and inspection to determine whether the observed damage was actual coating separation or only overspray.
What is ASTM E837?
ASTM E837 is the standard, semi-destructive test method for determining near-surface residual stresses in materials using the hole-drilling strain-gage method. This test method applies to isotropic, linearly elastic materials (such as metals). This method measures mechanical strain relaxation (release) as a small blind or through-hole is incrementally drilled into the metallic material. In this test method, a strain-gage rosette is attached to the surface, and a small hole is drilled precisely at its geometric center, and then relieved strains are recorded after each depth increment to calculate the magnitude and direction of the underlying residual stresses.
Tests Performed to Reach the Goal of Analysis
1. Residual Stress Measurement
Standard: ASTM E837
The hole-drilling method was used to measure the near-surface residual stress in the cladding. Small drilling steps were performed, and the stress profile was measured at one location on the sample.
2. Edge Delamination and Crack Evaluation
An alcohol wicking test was used to check whether the cladding had separated from the steel substrate. Dye penetrant testing was considered but was not performed because the rough, porous surface of the thermal spray coating would not provide reliable results.
3. Additional Edge Analysis
The edges of the sample were wet-ground using grit paper to remove overspray. This provided a clearer view of the interface between the cladding and the steel substrate and helped confirm whether the observed gaps were true delamination.
Results Analysis and Interpretation
The following results were obtained –
- Residual stress measurements were successfully completed using ASTM E837.
- Delamination of the cladding was confirmed along the edges of the sample.
- Smaller areas of separation were also seen along the edges, but they were less severe.
- Alcohol entered the gaps at the edges, confirming that separation was present.
- Wet grinding removed the overspray and confirmed that the cladding had separated from the steel substrate.
- Possible surface cracks were seen near the edges during the alcohol test, but they could not be confirmed under magnification.
Conclusion and Discussion
The results obtained above showed that the cladding had separated from the steel substrate in several areas, especially along the edges. The additional grinding step confirmed that the observed damage was true delamination, not overspray. Residual stress measurements were completed successfully, providing valuable information about the cladding’s condition.
Why Should You Choose Matestlab for ASTM E837 Testing?
Matestlab provides ASTM E837 testing services through expert laboratories based in the USA. Matestlab is your unified testing partner for physical, thermal, chemical, electrical, mechanical, environmental, and characterization testing needs, supported by our global network of 2200+ accredited testing laboratories. Our in-house materials science experts curate and design comprehensive testing programs matched to your sample material and ASTM E837 testing requirements, keeping regulatory requirements in mind.
If you are looking for a managed and trusted testing partner to achieve your research goals, feel free to schedule a meeting with us or send us a request at connect@matestlabs.com to learn more about our services. The best way to get a quote quickly is to call us at (302)244-7710. We are happy to support you.
FAQs
1. What is the cost of ASTM E837 residual stress testing?
The ROM cost is $2,250 per sample, plus applicable reporting charges.
2. Is ASTM E837 a destructive test?
ASTM E837 is considered a semi-destructive test because a small hole is drilled into the specimen to relieve residual stresses and measure the resulting strain.
3. Can the customer request specific measurement locations?
Yes. The customer can identify the areas of interest on the component or provide a drawing/photo indicating the desired measurement locations. The laboratory can then review the requested locations for suitability.
4. What information is included in the final report?
The report can include the ASTM E837 residual stress results, measurement location, stress profile, relevant test observations, photographs, and findings from the cladding/edge inspection included in the agreed scope.
