Abstract
Laser alloying is an effective method to form functional surface layers (coatings) on metallic materials, particularly on stainless steels. Unique phase balance, dislocation substructure, and a possibility to obtain gradient microstructures after laser alloying slow down the surface degradation and increase the wear resistance. In this work, the optimal parameters of laser alloying and their effects on microstructure and properties were investigated for two stainless steels: ferritic AISI 420 and austenitic AISI 304. Three types of alloying plasters were used: 85Nb + 15 graphite, 85Nb + 15 liquid glass, and 15Fe + 30Ni + 20B + 10Si + 25 liquid glass (wt.%). The laser power density of 0.3 × 105 W/cm2 and beam scanning speed of 1990 mm/min were found to generate 220–320 μm thick coatings with complex microstructures. Phase balance in the coatings was studied with X-ray diffraction and magnetometric phase analyses. High microhardness (up to 16 GPa) and wear resistance were associated with the formation of martensite with some retained austenite and Nb-, Cr-, Si-, and B-rich particles in the surface layer of AISI 420 steel, and high dislocation density austenite strengthened with Ti-, Nb-, Cr-, and Si-rich particles in AISI 304 steel.
Highlights
Accepted: 2 March 2021Structural materials applied in power generation and metallurgical industries to transport different high-temperature substances have shown various degradation mechanisms
In the area heated to a temperature zones
After laser alloying of AISI 304 steel with a plaster of 85Nb + 15% liquid glass, the surface layer consists of two zones
Summary
Structural materials applied in power generation and metallurgical industries to transport different high-temperature substances (salt solutions, superheated steam, molten metals) have shown various degradation mechanisms. The controlled formation of a certain microstructural state and phase balance in the surface layers will significantly improve the bulk properties and increase the operating life of machine parts and structural elements of power equipment [1]. The level of compressive residual stresses will increase towards the surface In this way, it was possible to increase the corrosion and wear resistance of vanadium alloys of the V-Cr-Ti system and stainless steels [31,32,33,34], used for manufacturing of thermal and nuclear power plant components (turbine blades, throttle washers, shut-off valves, energy steam generators, feed pump jackets, valve surface seals) and various machine parts in airspace, radio electronics and precision manufacturing industries (small parts that undergo friction and wear in aggressive environments). The strengthening mechanisms are discussed on the basis of detailed microstructural characterization and analysis of the microstructure-properties relationships
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
