Is it necessary to conduct impact tests on welding test plates of stainless steel products?
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This post was last edited by qzn165_WGZL on 2021-7-30 at 15:56. As the title indicates, it concerns the impact test for welded test pieces of stainless steel products. According to NB/T47016-2011, page P53, when technical specifications and design documents related to pressure-bearing equipment require impact tests on welded joints, impact tests must be conducted on the product’s welded test pieces. Page P62 of NB/T47016-2011 states that for chromium-nickel stainless steel specimens, the lateral expansion amount also needs to be provided. On page P167 of NB/T47016-2011, for low-temperature impact tests, the acceptance criterion for chromium-nickel stainless steel changes to impact absorption energy. Questions: 1. If the technical requirements specified in P53 do not call for an impact test, and stainless steel material standards generally do not require such tests either, is it still necessary to conduct an impact test on the product test pieces? 2. Since page P62 requires the measurement of lateral expansion amount for chromium-nickel stainless steel, does this necessarily mean that an impact test must also be carried out? 3. According to page P167, if there are no low-temperature design requirements, what is then the acceptance criterion for stainless steel product test pieces, and is an impact test required?
If the technical requirements do not specify impact testing, then stainless steel material standards generally also do not include such tests
Generally, impact testing is not required, unless specifically requested.
How should the statement in NB/T47016-2011 that specimens of P62 chromium-nickel stainless steel should also provide data on lateral expansion be understood?
How should the statement in NB/T47016-2011 that specimens of P62 chromium-nickel stainless steel should also provide data on lateral expansion be understood?
The lateral expansion amount should also be provided, indicating that it is not just the lateral expansion amount that is given
Impact energy, fiber cross-sectional area, and lateral expansion are three commonly used parameters in Charpy impact testing. Lateral Expansion (LE) is numerically equal to the sum of the maximum expansions in the directions perpendicular to the crack path on either side of the specimen’s cross-section. In foreign standards and specifications, impact energy is generally used as the main indicator to assess the low-temperature toughness of materials, while lateral expansion can also be used as an independent indicator in certain special cases. For example, the ASME BPVC specification employs the lateral expansion value to evaluate the toughness of high-alloy steels at liquid nitrogen temperatures, as well as the toughness of high-strength steels and ferritic steels that have been strengthened through heat treatment ； Furthermore, for materials whose relationship between impact energy and lateral expansion is not clear, it is required to be specified as an indicator along with the impact energy. Domestic standards such as TSG 21-2016, GB/T150, and the draft version of the new HG/T20585 also mention the lateral expansion amount; let’s take a look at each of them.
1. If the technical requirements do not specify any impact tests, then stainless steel material standards generally also do not require such tests. Whether impact tests are necessary for the product specimens depends on whether the standards or the product drawings specify it; in the absence of such requirements, the welded specimens of the product do not need to undergo impact tests. 2. For chromium-nickel stainless steel, lateral expansion needs to be provided – is it necessary to conduct impact tests? How can lateral expansion be determined without carrying out impact tests? 3. If low-temperature design requirements do not apply, what are the acceptance criteria for stainless steel product specimens? Is impact testing required? The acceptance criteria for welded product specimens are specified in standard NB/T47016; again, the question of whether impact testing is necessary comes down to the first question.