ISO 6892-2: dragprovning av metallmaterial vid förhöjda temperaturer
ISO 6892-2 is one of the most commonly used testing standards for the tensile testing of metallic materials at elevated temperatures (above 35℃). ISO 6892-2:2018 is the current version of the metals testing standard. It was first published in 2011, when it canceled and replaced the previous standard governing elevated temperature testing - ISO 783: 1999.
Elevated temperature testing is most commonly used in the aerospace industry, where metallic materials in aircraft engines and structures must exhibit high strength while running at high temperatures. This form of testing has become increasingly important in aerospace metals, as higher engine service temperatures are desired for improved efficiency. Similarly, ISO 6892-2 is relevant to important applications in power generation, Bilkomponenter och petrokemisk utrustning . varhelst metallfästelement, hårdvara eller strukturella komponenter förväntas bära belastningar i heta miljöer, iso 6892-2 möjliggör en standardiserad bestämning och kvalifikation av deras viktiga tensilegenskaper .
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ISO 6892-2 describes two methods of elevated temperature testing, Method A and Method B. Since test speed typically has a much greater influence on mechanical properties at elevated temperatures compared to testing at room temperature, both methods strictly control the strain rates allowed while these properties are determined. This, along with narrow tolerances (±20%), minimizes measurement uncertainty of test results and lab-till-lab variation .
Method A is especially well suited for minimizing uncertainty and variability, hence its preferred use in the aerospace industry. It applies a narrow tolerance to a slower test speed that improves the repeatability of results, especially at higher temperatures. ISO 6892-2 also provides an alternative method for comparing room temperature test results directly to elevated temperature results at the same strain rates and toleranser . Detta är syftet med metoden b .
In the standard's Annex, ISO 6892-2 provides example comparisons of multiple specimens tested at varying strain rates in room temperature test conditions, and then multiple specimens of the same alloy tested at elevated temperatures (850℃). It's clear from these figures that strain-rate sensitivity increases significantly with higher temperatures.