Determination of the scale mass on the surface of steel wire rod by metallographic method

Abstract

A net detrimental effect of acid vapors on human health and environment characteristic for chemical methods of descaling the surface of steel wire rod, as well as the difficulties in the disposal of pickling sludge dictate the need for developing a new methodology free of the aforementioned shortcomings. A metallographic method for determining the mass of scale on the surface of a steel wire rod subjected to two-stage cooling is proposed. The tests were carried out in accordance with the requirements of current standards for assessing the accuracy (correctness and precision) of methods and measurement results. The proposed metallographic approach appeared advantageous for proved reliability of the scale mass determination with the required accuracy at a confidence level of 95%; for significant reduction in the material consumption due to the absence of the need for special sample preparation; reduction of the test time due to determination of metallographic parameters in parallel with optimization of the descaling procedure through scale dissolution in a pickling solution and protection of the base metal with the inhibitors; for elimination of using acids and, as a result, the necessity of waste disposal. Apart from quantifying the scale content, the method provides for determination of the phase component ratio. It is shown that the metallographic method, including determination of the scale mass by measuring the thickness of the layers of the scale phases (wustite, magnetite), can be used as an alternative to the traditional standardized method for rapid determination of the scale amount and X-ray structural analysis of the phase composition.