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102 Upper yield stress (ReH) is the highest value of stress
measured at the commencement of plastic deformation at
yield; often this value is represented by a pronounced peak
stress. The test shall be carried out with an elastic stress rate
not exceeding 30 N/mm2 per sec.
103 When no well-defined yield phenomena exists, either
the yield strength at 0.2% non-proportional elongation (Rp0,2)
or the yield strength at 0.5% total elongation (Rt0.5) shall be determined
according to the applicable specification. The test
shall be carried out with an elastic stress rate not exceeding 30
N/mm2 per sec.
104 For determination of tensile strength (Rm) of ductile materials,
the speed of the testing machine during the tensile test
shall not exceed that corresponding to a strain-rate at maximum
load of 40%/min. For brittle materials, like cast iron the
elastic stress rate shall not exceed 2.5 N/mm2 per sec.
105 The elongation generally means elongation determined
on a proportional gauge length , or 5 d and has the
designation A5.
If the material is a ferritic steel of low or medium strength and
not cold worked, the elongation may also be measured on a
non-proportional gauge length Lo after agreement with the Society.
In that case the required elongation Ao is calculated from
the following formula: |
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发表于 2008-3-24 09:29
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都是牛XX哦