If you are an ASTM Compass Subscriber and this document is part of your subscription, you can access it for free at ASTM Compass
    ASTM E517 - 19

    Método de ensaio padrão para Razão de deformação plástica r para chapa de metal

    Active Standard ASTM E517 Developed by Subcommittee: E28.02

    Book of Standards Volume: 03.01


      Format Pages Price  
    PDF 11 $200.00   ADD TO CART

    Historical Version(s) - view previous versions of standard

    Translated Standard(s): English

    ASTM License Agreement

    More E28.02 Standards Related Products


    Significance and Use

    4.1 The plastic strain ratio r is a parameter that indicates the ability of a sheet metal to resist thinning or thickening when subjected to either tensile or compressive forces in the plane of the sheet. It is a measure of plastic anisotropy and is related to the preferred crystallographic orientations within a polycrystalline metal. This resistance to thinning or thickening contributes to the forming of shapes, such as cylindrical flat-bottom cups, by the deep-drawing process. The value of r , therefore, is considered a measure of sheet-metal drawability. It is particularly useful for evaluating materials intended for parts where a substantial portion of the blank is drawn from beneath the blank holder into the die opening.

    4.2 For many materials the plastic strain ratio remains essentially constant over a range of plastic strains up to maximum applied force in a tension test. For materials that give different values of r at various strain levels, a superscript is used to designate the percent strain at which the value of r was measured. For example, if a 20 % elongation is used, the report would show r20.

    4.3 Materials usually have different values of r when tested in different orientations relative to the rolling direction. The angle of sampling of the individual test specimen is noted by a subscript. Thus, for a test specimen whose length is aligned parallel to the rolling direction, plastic strain ratio, r , is reported as r0. If, in addition, the measurement was made at 20 % elongation and it was deemed necessary to note the percent strain at which the value was measured, the value would be reported as r020.

    4.4 A material that has an upper yield strength (yield point) point followed by discontinuous yielding stretches unevenly while this yielding is taking place. In steels, this is associated with the propagation of Lüders' bands on the surface. The accuracy and reproducibility of the determination of plastic strain ratio, r , will be reduced unless the test is continued beyond this yield-point elongation. Similarly, the discontinuous yielding associated with large grain size in a material decreases the accuracy and reproducibility of determinations of plastic strain ratio, r , made at low strains.

    1.1 Este método de ensaio cobre o ensaio de tração especial para medição da razão de deformação plástica, r, de chapas metálicas destinadas a aplicações de embutimento profundo.

    1.2 Os valores indicados em unidades de polegada-libra devem ser considerados como padrão. Os valores entre parênteses são conversões matemáticas para unidades SI fornecidos apenas para fins de informação e não são considerados padrão.

    1.3 Esta norma não pretende abordar todas as preocupações de segurança, se houver, associadas à sua utilização. É responsabilidade do usuário desta norma estabelecer práticas apropriadas de saúde, segurança e meio ambiente e determinar a aplicabilidade das limitações regulatórias antes do uso.

    1.4 Esta norma internacional foi desenvolvida de acordo com os princípios internacionalmente reconhecidos sobre padronização estabelecidos na Decisão sobre os Princípios para o desenvolvimento de normas, guias e recomendações internacionais emitidos pelo Comitê de obstáculos técnicos ao comércio (TBT) da Organização Mundial do Comércio.