Reading Material Test Reports

Understanding Material Test Reports (MTRs) can be difficult to the uninitiated or to those who seldom need to interpret them.  There is no standard format for reporting the required information.  Each producing mill has generated their unique version of the report.  In some cases mills indicate their ability to modify the format, or the information, is limited because of internal system constraints.

There are some commonalities.  Each test report should have a section that identifies the alloy, heat number, specification(s) and product form, size and condition.  Unfortunately, the condition that is reported does not always translate into a clear understanding of what is being supplied.  For example, cold finished, cold worked and strain hardened may all sound similar, but mean different things.

There will be a section reporting the ladle analysis of the heat.  There may also be a second chemistry reported as a Check or Product analysis. For most materials, the melt practice is not required to be reported. Mills use different abbreviations for different melt practices. EF-AOD is a common way to indicate the melt was by Electric Furnace followed by Argon Oxygen Decarburization. VIM-ESR indicates Vacuum Induction Melting followed by ElectroSlag Remelting.  The chemistry may report residual elements that are not actually required to be analyzed.  This is permitted and does not mean there is something present that shouldn’t be.

Another section of the test report will show mechanical properties.  The information reported will vary by alloy and by specification requirements.  Flat products for many grades require simple room temperature yield strength (0.2% YS), tensile (UTS), elongation (E%) and hardness.  Bar products typically also require reduction of area (RA%).  Some materials also require impact toughness testing on a Charpy V-Notch (CVN) sample.  These tests are performed at sub-zero temperatures and the results are reported as impact energy and a measure of lateral expansion ductility.

Alloys that can be thermally hardened will also show the results of CAPABILITY tests. These are tests performed on heat treated samples of the supplied material to demonstrate the materials’ ability to achieve the required properties.  For a martensitic grade, like 410 stainless, this will simply be a hardness reading.  For a material like 17-4PH, aged room temperature tensile properties will be listed in addition to as-shipped properties.  Some thermally hardenable materials like 718 will require elevated temperature capability testing. This can involve elevated tensile tests as well as stress rupture testing. At elevated temperature, loads below the yield strength can cause materials to elongate and fail over time.  These tests may take several days to complete and the results are usually reported in hours to failure.  There may be more than one set of properties reported if testing is being done to more than one specification.   The results will generally be distinguished by the heat treatment practice used to determine the capability. Remember that CAPABILITY test results are from heat treated samples and do not represent the actual condition being supplied.

Depending on other requirements of the specification or purchase order, there may be test result data reported for grain structure, corrosion testing, magnetic properties or more.  With so many different styles, languages and terms, even veteran metallurgists may need extra time to decipher the results on a test report.  If you need help understanding what is being reported, don’t hesitate to call our Metallurgical Services or Quality Assurance groups.