Method of 10 per cent oxalic acid etch test for stainless steels

This document establishes a standardized procedure for evaluating the corrosion resistance of stainless steel through an oxidative etching process using a specific concentration of oxalic acid. The test method involves immersing prepared metal specimens in a 10% solution to induce a controlled surface reaction that reveals microstructural characteristics related to sensitization. By examining the resulting etched surfaces under magnification, technicians can identify the presence of carbide precipitates along grain boundaries, which indicates susceptibility to intergranular corrosion in certain environments. The protocol specifies the preparation of the electrolyte, the precise duration of immersion, temperature control during the reaction, and the necessary safety precautions for handling chemical reagents. It also outlines the criteria for classifying the quality of the etch based on the observed microstructure, providing a consistent framework for quality assurance and material selection in the manufacturing sector. This approach ensures that assessments are reproducible across different laboratories and industries, supporting the reliability of stainless steel products in various applications without relying on subjective visual inspections. The methodology focuses on the technical execution of the test rather than the material specifications themselves.