Chemical Process Test Specimen Material
|Publication Date:||1 May 2007|
This standard establishes definitions, guidelines, and requirements governing the specific material (e.g., alloy and heat treat condition) to be used for chemical process test specimens when requirements call for "the same generic class of alloy".
This standard has been used typically for plating and chemical finishing processes, but usage is not limited to such applications. Corrosion test specimens and hydrogen embrittlement test specimens generally have specific test requirements and are excluded from this document.
Test samples utilized in metal finishing serve an important function in assuring the quality and functionality of the plating or coating produced. Some attributes of surface finishes can be directly tested from actual parts that will see field service, and the testing of actual plated/coated parts is always preferred. However the testing of actual parts must always be nondestructive in nature, that is, any tests that can alter, disturb or remove a plating or coating will result ultimately in the rejection of the test part from delivery. Since metal finishing by definition is a topical plating or coating, many of the physical attributes of the plating/coating can be easily, economically, and accurately destructively tested using samples representative of the base metal being processed. The selection of appropriate test sample material and size establishes the foundation of quality acceptance of the metal finishing process. When testing for the quality attributes of the process, tests can be grouped in 3 categories:
a. Tests of the physical-dimensional
b. Tests of the coating/plating functionality: Examples of this are adhesion, corrosion resistance, electrical resistivity, coating weight, heat resistance, IGA-Surface attack, etc. Test sample material is very important as this category test measures the coating/plating relationships with the base metal.
c. Tests of coating/plating detrimental effects on the base metal: An example of this is hydrogen embrittlement and test sample material is of critical importance. Established industry testing protocol for hydrogen embrittlement restricts test sample material and heat treat condition. (ASTM F 519 is an example.)
Current industry standards and specifications allow separate test specimens under certain conditions and the reader should refer to the processing document specified by the procuring customer. Generally accepted requirements state: "separate test specimens shall be made of the same generic class of alloy as the parts, distributed within the lot, cleaned, plated, and post treated with the parts."
This document establishes policy for separate test specimen material that is required to be of the "same generic class of alloy" as the parts processed. While specimens of the same alloy and heat treat condition are acceptable to represent the parts processed, the materials listed herein have also found general acceptance across the industry.