Pérdida de ductilidad en acero comercial tipo Hadfield por formación de perlita

M. RAPOSO, M. MARTÍN, M.F. GIORDANA, J. MALARRIA

Córdoba

Congreso; 16º Congreso Internacional de Metalurgia y Materiales - Simposio Materiales y Tecnologías para la Industria Metalmecánica y Aeroespacial; 2016

Sociedad Argentina de Materiales

The Hadfield steel is a wear resistant material broadly employed in heavy machinery for mining, hammer mill crushers and railways crossing among other applications[1,2]. Despite its relevance as industrial material there is a lack on detailed investigations covering the relationship between microstructure and mechanical properties on Hadfield steels. While austenite and carbides are the usual constituents, pearlite formation can also occur in this material. This work presents the occurrence of pearlite in commercial Fe-12.6Mn-1.01C Hadfield manganese steel due to wrong metallurgical practices. Pearlite formation affects about 20% of the material and is responsible for an 85% reduction inelongation to rupture assessed by means of tensile tests. Secondary electron microscopy (SEM) showed that pearlite nucleation occurred preferentially on austenitic grain boundaries and inside of the grains by forming islands. The pearlite is very thing with a lamellar spacing between 40nm and 130 nm according to SEM micrographs. Further TEM observations showed even lower spacing up to 18 nm. Additionally, the stacking faults in the austenitic matrix were characterized by means of TEM. Finally, a short heat treatment feasible at industrial conditions is proposed asalternative to recover the ductility of the alloy. The heat treatment is able to recover ductility without lowering the strength and without modifying the chemical composition of the material.