取样方法和样品制备

本文旨在描述与取样方法和样品制备相关的“传统”概念和指导方法，给出了应用于钢铁以外的其他冶金分析领域的操作程序相关信息。然而，这些概念和程序绝大部分同铸造行业知识相关，与需要特别操作（如果需要相关操作）的其他可能领域并不相关。取样本身是个“无用”功，必须把这种行为当做“三角”工序中的一个角，而其他两个角是关注的基质和需要应用的技术。对样品制备适用性方面也进行了详细描述，应该考虑到采用的合金和要应用到的分析技术（方法）。鉴于实验样品是从“一块”样品中制取，应该注意到样品重新熔化的可能性和相关局限性。还要强调与制备缩分样品相关的一些特殊情况。与此同时，要注意到负责这些任务的操作者以及将“各种样品”送到实验室的客户（可称为第三方）的专业技能（或者说缺乏专业技能的情况）。最后，将指出“取样和样品制备”的现有标准以及与这些文件内容相关的“投诉”，因为有些内容的“强制性”不足，可能会导致“不好的”检测结果。

Sampling method and sample preparation

This presentation aims to recall “old” concepts and instructions, regarding sampling methods and sample preparation.Information on the procedures used in other fields of the metallurgical analysis, besides that of steel, will be given.However, these concepts and procedures are mostly linked to the foundry industry knowledge rather than to other possible fields requiring specific operations (if any).Sampling by itself is an “useless” action: it has to be taken as a corner of a “triangular” process, where the other two are the matrix under concern and the technique(s) to be used.A fourth “dimension” - the preparation of the sample - will also be detailed regarding its suitability, taking into account the alloy and the analytical technique (or method) supposed to be used.In cases of samples taken from a “piece”, warning on the re-melting possibilities and limits will be reminded.Some particular cases related with the preparation of divided samples will also be underlined.In parallel, the expertise (or rather, the lack of expertise) of operators in charge of these tasks will be reminded, together with that of customers sending “all kind of sample” to a laboratory (namely the third party ones).At last, the existing standards on “Sampling and sample preparation” will be pointed out, together with a “complaint” regarding the content of these documents, as some of them are not enough “mandatory”: they may lead therefore to some “bad” practices.