Relationship between processing parameters, alloy atom diffusion distance and surface hardness in laser hardening of tool steel

Effects of interface formation kinetics on the microstructural properties of wear-resistant metal–matrix composites

“…The activation energy, which describes the temperature dependence of the kinetic rate constant, showed higher values (405 kJ/mol) for internal layer growth compared to the outer layer (309 kJ/mol). These results are close to the activation energy values reported for diffusion-controlled processes of carbide dissolution in the literature [19,24]. Results for the time-dependence coefficient (n) were 0.61 ± 0.13 and 0.92 ± 0.18 for the internal and outer layer, respectively.…”

“…This results in changes of the chemical gradients and of the mechanical behaviour of the interfacial reaction layer between carbide and matrix. The most obvious influence is exerted by temperature and time [19]. Kinetic changes depending on processing time, temperature and chemical composition of metal-matrix composites, in combination with statistical correlations with the micro-mechanical properties of microstructures, is an important and suitable tool in the quantitative characterisation and optimisation of the product and process parameters.…”

The Influence of Retained Austenite on Residual Stresses in Laser Remelted Cast Iron

“…Thus, the aim of surface remelting process is to ensure a fine-grained microstructure with uniform microhardness, which cannot be achieved by other procedures for surface hardening of pearlite-ferrite cast irons ( Ref 9). The properties of the modified layer depend on the microstructure prior to heat treatment and on the amount of energy input transferred to the surface layer of the specimen ( Ref 10,11). This study discusses the different effects of the laser remelting process on the microstructural changes in the surface layer as well as residual stresses developed in the nodular cast iron 500-7.…”

Influence of processing conditions on the carbide/matrix interface in sintered composite layers

“…The interfacial layer results as a reaction product during processing caused by tungsten carbide dissolution [15][16][17][18] or decarburization [19,20] in the melted metal matrix and precipitation of secondary carbides, borides and/or other phases containing W, Ni, Cr and other alloying elements. The formed interfacial layer influences the micro-hardness profile between matrix and carbide [13][14][15] that improves bonding [21] and consequently, the MMC's wear resistance.…”

“…There are various factors, which influence the interfacial layer formation during MMC processing. The most obvious influence is the incorporated temperature and the time [17,18]. This results in changes of the chemical component gradients and on the mechanical behaviour of the interfacial layer in the area between the carbide and matrix.…”