PROCESS FOR THE SUPERFICIAL HARDENING IN STEELS BY MEANS OF A BORON-NITRIDING THERMOCHEMICAL TREATMENT IN POWDER, PERFORMED IN TWO STAGES.

摘要

The present invention refers to a process for the superficial hardening in steels by means of a boron-nitriding thermochemical treatment in powder, performed in two stages. The superficial hardening process of the present invention describes the construction of stainless steel AISI 304 metallic containers where the samples subjected to the treatment are introduced, also describing the selection of the steels to be exposed to the thermochemical treatment, the preparation of the powder including boron carbide for carrying out the first stage of the treatment, the preparation of the mixture including calcium cyanamide powder and the silicate compound for performing the second stage of the thermochemical treatment, the process finishing with the inspection and the physic-chemical and mechanical characterisation of the boron-nitriding layers formed onto the surface of the hardened steels. The process for the superficial hardening of steels by means of a thermochemical treatment of boron-ni triding in powder performed in two stages generates the presence of a system of Fe4N, FeB and Fe2B layers for increasing the mechanical, physical and chemical properties over the surface of different steels exposed to this treatment. The boron-nitriding layers are highly resistant to abrasion, erosion, corrosion and present a suitable adherence over the steel since the hardness in the material surface is substantially increased. The thickness of the boron-nitriding layers depends on the temperatures of the process, the times of the treatment and the chemical composition of the steel. The invention also refers to the application of the different steels subjected to this thermochemical treatment.