Mechanical and Electrochemical Evaluation of Organic Inhibitors Effect on Mild Steel Damage by Hydrogen

Hydrogen penetration into the bulk of steel is a risk during the whole process of the manufacturing of steel product. Hydrogen accumulation in the material structure can induce the adverse changes in mechanical/metallurgical properties, i.e. cause hydrogen blistering or even hydrogen embrittlement. Consequently, when the product is subjected to mechanical stress, cracking hazard occurs. In this study, we focus on hydrogen ingress during pickling of mild steel in strong acids (diluted sulphuric and hydrochloric acid. Generally, pickling is the critical step of the coating process. Different types of adsorption inhibitors were used as additives to pickling bath in order to prevent metal dissolution and related hydrogen evolution. The effect of inhibitors was tested by electrochemical and mechanical methods. Polarization curves measurement was used to evaluate corrosion rate of mild steel substrate in pure and inhibited acid solutions. Mechanical tests were performed using Cyclic Loading Pulsator, which is an experimental device simulating cyclic stress. Thus, the fatigue life of retaining rings for shafts exposed to the tested solutions was determined. Based on the results the most effective inhibitors were chosen.