Comportement des aciers inoxydables soumis à l’érosion par des particules solides en milieux agressifs

Behaviour of stainless steels submitted to erosion by abrasive particles in corrosive media

Creusot Loire Industrie, CRMC, Le Creusot

Résumé

Abstract

In industrial media, materials are often submitted to the effects of corrosive fluids containing abrasive particles. Stainless steels are generally used for these applications because of their mechanical properties and their ability to repassivate in corrosive environments.

The study of materials damage in erosion-corrosion conditions is certainly difficult, but this approach is necessary due to the importance of this destruction form. In order to investigate materials behaviour, an experimental set-up intended to simulate erosion-corrosion conditions induced by particle-containing fluids was developed. The slurry jet device was designed to control accurately hydrodynamic conditions and to obtain reproducible erosion conditions. The main parameters such as fluid velocity, electrochemical potential and pH were measured during experiments. Different analytical methodologies were developed in order to evaluate the synergistic effects between the corrosive damage and the mechanical wear and to follow the evolution of corrosion and erosion contributions versus erosion rate.

Erosion-corrosion experiments were performed in H₂SO₄ solution on austenitic, duplex and martensitic stainless steel grades, at various pH levels and erosion regimes. The main results of these tests show that:

- the chemical composition of investigated stainless steels is a significant criterion in corrosive media without erosion ;

- in non-corrosive or slightly corrosive media, dissolution rates increase with erosion regime, but hardness and mechanical properties appear as the main criteria ;

- in corrosive environments, whereas only the martensitic grade is highly corroded without erosion, the dissolution rates are highly increased by erosion for all tested alloys. Chemical composition together with mechanical properties are significant criteria in aggresive corrosion-erosion conditions ;

- in erosion conditions, the corrosion contribution to the total wear achieves more or less rapidly a maximum value while the erosion damage increases with the particle concentration.