Questions regarding the chemical composition table for forgings in NB/T47010-2017
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Our company has received a batch of forgings made of S31603 material; tests using a handheld spectrometer revealed that the Cu content is 0.348%, V content is 0.158%, and Pb content is 0.058%. Refer to Table 1 of specification 47010 for the grades and chemical compositions of the forgings; Pb and V are not listed in this table, and the value for Cu is “-”. Based on this, we determine that these forgings are unqualified. The supplier stated that the presence of trace elements is acceptable and does not constitute a defect. Please ask an expert to help provide an analysis.
The PMI method is not sufficient for rejecting items; it is recommended to perform further analysis
Hello everyone. What I mainly want to ask about is the interpretation of the chemical composition table. It is generally understood that if a standard does not specify any requirements for certain elements, then those elements need not be listed in the standard. Since they are included in the chemical composition table and marked with “—”, it should mean that such elements are either not present at all or their concentration is so low as to be negligible. Is there an exact interpretation for this? How to use this chemical composition table to determine whether the chemical composition of the forged part is qualified.
The bar indicates that it is not a criterion for evaluation, and it does not mean that the concentration of that chemical element is “zero”; therefore, it is unreasonable for your organization to deem the sample unqualified on the grounds of the presence of trace elements. The supplier’s response isn’t meant to deceive you; it is correct. From the perspective of material requirements, the chemical composition is primarily determined by the material’s structure and corrosion resistance ； Mechanical properties relate to the heat treatment of materials, while weldability ensures that the materials can be welded properly and that cracks in the welds are avoided.
Thank you. Since no response was received earlier, I called the bidding committee to confirm the matter. “—”What it means is to make no demands. As long as the contents of the other elements in the table meet the requirements, it is considered satisfactory.
Furthermore, the results obtained using a handheld spectrometer cannot be used as a basis for determining rejection. It must be an arbitration analysis method in order to render it invalid. However, the cost of arbitration analysis methods is quite high.