Why is only hardness testing performed on Grade I forgings?
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As the title suggests, why are only hardness tests performed on Grade I forgings? This question is often encountered when preparing for exams, but one doesn’t know how to explain it. Let’s discuss it together. :)
Anyway, there’s no place to use it. . . To maintain the integrity of this forging grade. . .
Low requirements; used for non-pressure vessel pressure-bearing components.
Levels II, III, and IV undergo tensile testing, which allows for the determination of properties such as Rm and Rel of the forgings. For grade I, these mechanical properties cannot be obtained without conducting tensile tests; only hardness values can be determined. Is there a conversion formula between hardness values and parameters such as Rm?
It’s of course no problem using it on structural components.
Grade I forgings do not provide strength values! ? What logic is this? The tables of allowable stresses and mechanical properties for 150 and forgings do not state that grade I forgings are not applicable; in fact, the allowable stresses and mechanical properties are the same for all grades of forgings!
According to Table 2 of NB/T47008, the only inspection parameter for Grade I forgings is hardness. Logic: Grade I forgings do not provide strength parameters because, in the applications where such forgings are used, strength is not a factor that needs to be considered in the design. If the strength of the component needs to be considered during design, grade I forgings cannot be used.