Structure and Abrasive Wear Resistance of Stainless-Steel Surface Layers Alloyed with Boron

Abstract

The structure, microhardness, and tribological properties of coatings obtained in the process of surfacing of powder mixtures by an electron beam ejected into an air atmosphere are studied. For surfacing, we used a powder mixture containing amorphous boron and a wetting component, the role of which was played by Fe, Cr and Ni powder particles. The function of protecting the molten material from the air atmosphere was performed by MgF₂ flux. The thickness of the formed coatings reached 2.3–2.8 mm. The maximum level of microhardness of coatings reaches ~1500 HV. The main mechanism of hardening of such is due to the presence in the material of up to 90% (volume) particles of the hardening phase. It is shown that chromium borides Cr₂B and (Fe,Cr)₂B play the role of a hardening phase in the γ-phase (Ni, Fe solid solution). Chromium is contained in the alloying powder mixture and the base material. During the cladding process, chromium diffuses and forms borides. This process occurs due to the greater affinity of chromium for boron than nickel and iron. It has been established that chromium containing coatings have maximum wear resistance under various abrasive conditions. The wear resistance of coatings increased by 5 times compared to stainless steel 12Х18Н9T under friction with fixed abrasive particles. The wear resistance of hardened layers under conditions of gas and hydroabrasive action at low angles of attack (15°, 20°) increased by 6 and 2 times, respectively.