M. Michalski

An influence of active additives on the formation of selected indicators of the condition of the X10CrNi18-8 stainless steel surface layer in MQCL conditions

The paper presents the results of the research into the impact of anti-wear added to emulsion mist on the geometrical state of the machined surface of stainless steel after turning. In the research, the following machining conditions were compared: dry machining and cooling with compressed air, emulsion mist, emulsion mist + Crodafos O4A-LQ-(MH) and emulsion mist + Crodafos EHA-LQ-(MH). In the first stage, the influence of modifiers on roughness parameters of the machined surface were established. The aim of the second stage was to submit the machined material to microroentgenospectral analysis. The presence of chemical elements on the machined material surface for the aforementioned conditions of machining was analysed. Research results indicate that the application of cooling with emulsion mist with modifiers reduces the roughness parameters of the machined material even up to 80%. Adequately selected conditions of forming emulsion mist forms border layer, beneficially influencing the cutting conditions.

Structural and Microhardness Changes After Turning of the AISI 1045 Steel for Minimum Quantity Cooling Lubrication

This work presents the cooling effect under minimum quantity cooling lubrication and dry cutting on structural changes and microhardness of the ferritic-pearlitic AISI 1045 steel after turning. Due to the fact that the AISI 1045 steel has a two-phase structure, microhardness tests using the Vickers method were conducted with a load of 0.05 HV separately for ferrite and pearlite grains. The tests showed that cooling of the cutting zone under minimum quantity cooling lubrication (MQCL) condition decreased the depth of the hardened layer compared to dry cutting by approximately 40% for both pearlite and ferrite. Scanning electron microscopy analysis revealed that applying MQCL limits the formation of plastic deformations, among others, by reducing the surface crumple zone by approximately 50% compared to dry cutting. As a result of cooling being applied to the cutting zone using the MQCL method, the average diameter of ferrite grains has been decreased in the entire surface area compared to dry cutting. When using dry cutting, clear structural changes of the surface layer were also observed. This may be the result of sulfide inclusions which have formed, causing microcracks on the edge of the hardened layer and surface deformation visible as notches.

Tribological characteristics of composite coatings formed by laser cladding of powders of nickel self-fluxing alloy and bronze

Microstructures, coefficients of friction, and relative wear of composite coatings based on the PG-12N-01 nickel self-fluxing alloy and PG-19M-01 bronze have been considered. It has been found that composite coatings have a complex structure. The bronze coating, which is deposited on the fillets of the nickel alloy, crystallizes in a form of dendrites with axes arranged under an angle of 45°. The nickel alloy has a globular-dendritic structure with the eutectic component crystallizing between its branches. Momentary coefficients of friction in conditions of the concentrated load are independent of the cladding rate, and their values are 0.08–0.12 depending on the load. In this case, the wear rate of coatings depends substantially on the laser cladding. Under conditions of the distributed contact, bilayer coatings have a considerable advantage, and the relative wear is reduced by several tens of times compared with single-layer ones.