Effect of Hydrogen on the Mechanical Behavior on AISI 4140 with Borided Coatings

Abstract

In this work, the mechanical behavior on AISI 4140 with boride coating and hardened quenching-tempering was studies subsequently to boriding. The boriding is conducted at temperatures 1203 and 1233 K for 7 h, after that all samples at a temperature of 1143 K for 1 h and tempering 473 K were exposed for 1 h 30 minutes. The microstructural characterization was examined by scanning electron microscopy with saw-tooth morphology of boride coatings type Fe2B. Three-point bend test was used to study the effect of hydrogen cathodic charging on the mechanical behavior of AISI 4140 with boride coatings, the results show a reduction of ductility and 58.17% of indices of embrittlement () and show a crack on the substrate due to interaction of hydrogen atom. Also, sample boride at 1203 K with hydrogen show a low decrease of the bending stress with respectively a sample boride without hydrogen and a decrease of the parameter () with 35.32% due to the formation of boride coatings.