Stress relaxation vs creep compares two different time-dependent test questions. The referenced stress-relaxation method follows force change while keeping the specimen’s constraint approximately constant. The referenced tensile creep method follows deformation under constant tensile force and temperature.
For an aluminum component, retain the test method and conditions with the result. A general “long-term strength” heading is too vague to explain what was held, what changed and what the report demonstrates.
Four fields to read together
- The condition maintained during the test.
- The quantity recorded as time passes.
- The specimen, material and test environment.
- The application requirement the evidence must address.
On this page
Check 1: compare stress relaxation vs creep conditions
ASTM E328-26’s public scope describes stress-relaxation testing with approximately constant constraint, a constant test environment and negligible vibration. The required external force is tracked as time passes.
ASTM E139-24’s public scope describes deformation with time under constant tensile force and temperature. It also covers time-to-rupture measurement when sufficient force is present.
Keep the specified document, edition and applicable method in the test request. These public descriptions orient the review; they do not reproduce the complete standards.
| Report type | Main question to identify |
|---|---|
| Stress relaxation | How does the force change while the constraint is maintained? |
| Tensile creep | How does deformation change under the stated constant tensile force? |
| Rupture | What time to rupture is reported under the specified conditions? |
Ask the issuer to clarify which question its report answers. Avoid accepting a familiar method name in place of a defined test and reporting scope.
Retain the actual controlled conditions and any reported variation. If a field is missing, request the original record rather than filling it from a different specimen’s report.
Check 2: read the recorded quantity and its units
Start with the axes and column headings. Identify whether the report shows force, stress, deformation, strain or elapsed time. Keep the original quantity labels and units in your comparison.
If a summary shows a percentage, ask what reference value defines it. Retain the issuer’s calculation basis so the percentage can be interpreted without guessing.
For a stated change, identify the two readings and their times. A value without its starting reference can leave the purchasing team unsure what changed.
Keep the recorded result and acceptance limit in separate fields. An observed value is evidence; the purchase requirement supplies the criterion used to review it.
An original percentage example
Imagine a fictional force record starting at 800 N and later showing 680 N. The reduction is 120 N. Relative to the invented starting value, the reduction is 15%, while the remaining force is 85%.
Those two percentages describe the same fictional pair of numbers. A heading that says only “15%” omits whether the field represents reduction or retention.
This example illustrates labeling and arithmetic. It supplies no test duration, material grade, allowable reduction or prediction for an aluminum assembly.
Keep the original headings when copying the result into a quotation review. If a buyer wants another calculated display, label its basis and preserve the original record.
Check 3: preserve specimen, time and environment
Identify the specimen and its relationship to the supplied product. Keep alloy, temper, product form and relevant manufacturing history with the report.
For a machined component or assembly, retain its drawing and revision. Describe the delivered stage rather than shortening every specimen to “aluminum.”
Preserve the time reference, elapsed-time entries and recorded environment. Have the report issuer clarify any omitted condition that prevents the responsible reviewer from interpreting the evidence.
E328’s public discussion emphasizes maintaining the constraint and reporting its variation. E139’s public discussion emphasizes method identification and detailed reporting. Keep these limits visible when reviewing the evidence.
If two reports use different durations or environments, flag the difference before presenting them as equivalent offers. Ask the application reviewer which evidence covers the released requirement.
The aluminum residual-stress guide addresses an internal material-condition investigation. Keep that evaluation separately identified when the current request concerns a time-dependent test.
Check 4: connect the report to the intended use
Name the application question in the inquiry. Explain whether the responsible designer needs evidence about a constrained component, a loaded specimen or another defined configuration.
Keep the requested evaluation within its agreed scope. A report for stock material should not silently become an approval of every finished assembly made from that stock.
For a bolted aluminum assembly, retain the released joint description and assembly condition. The torque and preload guide helps distinguish the tightening input from the force requirement.
Ask the responsible technical reviewer how the time-dependent evidence applies to that assembly. Avoid treating a single initial tightening entry as a complete long-term evaluation.
If the purchase only includes cut blanks, define the blank’s dimensional and documentation requirements. Name any separate test or assembly scope rather than allowing it to remain implied.
Obtain the review decision for the actual application. A public test scope or a fictional calculation does not establish an allowable service load or a component lifetime.
Resolve an incomplete quotation before release
Consider fictional offer M46. It promises “long-term performance checked,” but supplies an initial material-strength value and no identified time-dependent test record.
Ask what the statement covers and which evidence supports it. Keep the original material data, then request the missing report scope if the order requires it.
Please identify the test method, edition, specimen, controlled conditions, time reference and recorded quantity supporting offer M46. Connect the report to the released application requirement and state any limitations on its use.
M46 is an original fictional document example. It is not a customer case, a measured result or a recommendation to qualify material using a particular test setting.
Keep the issuer’s reply with the offer and the technical review. If it changes the supplied scope, revise the confirmed order so the agreed evidence is clear.
Prepare the aluminum component handoff
Send the cutting supplier the full stock identity, section drawing, finished lengths and quantities. State which records must accompany the pieces and which downstream operations are planned.
Attach approved sample and identification requirements when the order includes material evaluation. Have the responsible reviewer define how the samples relate to the supplied parts.
Send JiurunCut your aluminum drawing and cutting requirements. Keep a stress relaxation vs creep review tied to the specified test, its evidence and the responsible application decision.
Can matching alloy names make two reports equivalent?
Compare the complete specimen identity, method, conditions and reporting scope before using either report for the order.
Does a time-dependent report approve every service condition?
Use it within the scope established by the responsible reviewer for the actual application.