Combined surface treatment of steel Hardox 450 is reported, which includes depositing a layer with Fe, C, V, Cr, Nb, W containing flux-cored wire by electro-contact method and its further irradiation by high-intensity pulsed electron beam. Tribological tests of the modified surface have been carried out and revealed the increase in wear resistance of the irradiated layer by 32.5 times as compared with the base material. The content of elements and the composition of phases, as well as the defect substructure of steel Hardox 450 and the deposited surface layer modified by high-intensity pulsed electron beam, have been explored by transmission and scanning electron microscopy. It has been indicated that a multilayer structure is formed due to electron-beam treatment of the deposited layer surface. The fact that interfaces of detected layers contain micro-pores and micro-cracks indicates their high-level consistency. A multiphase structure comprising α-phase and niobium-, chromium- and iron based carbide phases has been detected in the layer modified by the electron beam. With the help of electron beam treatment of the deposited layer surface it is possible to decrease significantly the sizes of inclusions located both in the modified layer and in the bulk of deposited metal. The average size of inclusions before exposure to electron beam irradiation is 2.5 μm, whereas those in the irradiated samples are 0.6 μm. The layer of deposited metal irradiated by the intense pulsed electron beam is in elastically-stressed state, as shown by numerous extinction bend contours in carbide phase. High-speed hardening of the deposited layer in the process of its pulsed electron beam irradiation leads to formation of massive martensite with ultra small cross sectional (40 – 70 nm) dimensions of martensite crystals.
ASJC Scopus subject areas
- Materials Science(all)