Abstract:The aim of the study was to synthesize and characterize the selected in-situ composites from the Fe-Cr-Ni-Mo-C system, additionally strengthened by intermetallic compounds. The project of the alloys was supported by thermodynamic simulations using Calculation of Phase Diagram approach via Thermo-Calc. Selected alloys were synthesized in an arc furnace in a high purity argon atmosphere using a suction casting unit. The studies involved a range of experimental techniques to characterize the alloys in the as-cast… Show more
“…Some published works concerning the in-situ synthesis of composite materials suggest that the experimental results should be complimented by the modelling and simulation of the solidification behaviour of the fabricated alloy system [18,19]. The use of computational thermodynamics allows an evaluation of phase stability in multicomponent systems as a function of temperature and composition and therefore provides the critical basis for understanding phase stability during the in-situ processing of composite materials [20,21].…”
TiC-reinforced composite surface layers (TRLs) on a ductile cast iron EN-GJS-700-2 grade (DCI) substrate were synthesized using a diode laser surface alloying with a direct injection of titanium powder into the molten pool. The experimental results were compared with thermodynamic calculations. The TRLs having a uniform distribution of the TiC particles and their fraction up to 15.4 vol % were achieved. With increasing titanium concentration in the molten pool, fractions of TiC and retained austenite increase and the shape of TiC particles changes from cubic to dendritic form. At the same time, the cementite fraction decreases, lowering the overall hardness of the TRL. A good agreement between experimental and calculated results was achieved. Comparative dry sliding wear tests between the as-received DCI, the TRLs and also laser surface melted layers (SMLs) have been performed following the ASTM G 99 standard test method under contact pressures of 2.12 and 4.25 MPa. For both the as-received DCI and the SMLs, the wear rates increased with increasing contact pressure. The TRLs exhibited a significantly higher wear resistance than the others, which was found to be load independent.
“…Some published works concerning the in-situ synthesis of composite materials suggest that the experimental results should be complimented by the modelling and simulation of the solidification behaviour of the fabricated alloy system [18,19]. The use of computational thermodynamics allows an evaluation of phase stability in multicomponent systems as a function of temperature and composition and therefore provides the critical basis for understanding phase stability during the in-situ processing of composite materials [20,21].…”
TiC-reinforced composite surface layers (TRLs) on a ductile cast iron EN-GJS-700-2 grade (DCI) substrate were synthesized using a diode laser surface alloying with a direct injection of titanium powder into the molten pool. The experimental results were compared with thermodynamic calculations. The TRLs having a uniform distribution of the TiC particles and their fraction up to 15.4 vol % were achieved. With increasing titanium concentration in the molten pool, fractions of TiC and retained austenite increase and the shape of TiC particles changes from cubic to dendritic form. At the same time, the cementite fraction decreases, lowering the overall hardness of the TRL. A good agreement between experimental and calculated results was achieved. Comparative dry sliding wear tests between the as-received DCI, the TRLs and also laser surface melted layers (SMLs) have been performed following the ASTM G 99 standard test method under contact pressures of 2.12 and 4.25 MPa. For both the as-received DCI and the SMLs, the wear rates increased with increasing contact pressure. The TRLs exhibited a significantly higher wear resistance than the others, which was found to be load independent.
“…Figure 8(a) reveals that delta ferrite was enriched in Cr and W in comparison to the matrix, which is a consequence of strong elemental partitioning during solidification and high carbon affinity. The ferritic zones are preferential sites for the nucleation and growth of carbonitrides [22]. Moreover, EDS (Figure 8(b)) showed that both martensite and delta ferrite mainly contained Fe, Cr and W. Figure 8 EPMA and EDS analyses of alloying elements distributions in the microstructure after standard heat treatment; (a) SEI image and element (Cr and W) mapping and (b) EDS spectrum of delta ferrite and martensite.…”
Section: Resultsmentioning
confidence: 99%
“…Figure 8(a) reveals that delta ferrite was enriched in Cr and W in comparison to the matrix, which is a consequence of strong elemental partitioning during solidification and high carbon affinity. The ferritic zones are preferential sites for the nucleation and growth of carbonitrides [22]. Moreover, EDS (Figure 8(b)) showed that both martensite and delta ferrite mainly contained Fe, Cr and W.…”
Effect of thermal treatment on the evolution of delta ferrite was studied in 11Cr–3Co–2.3W steel. Ferrite-forming alloy elements promoted the formation of delta ferrite during thermo-mechanical processing. The results of JMatPro and chromium equivalent calculations indicated that 11Cr–3Co–2.3W steel partially contained delta ferrite. Cr and W were segregated in/around delta ferrite. Delta ferrite had a bamboo-type morphology and it contained MX-type carbonitrides inside and the Laves phase at the interface between delta ferrite and martensite. On annealing, delta ferrite dissolved especially during the early stage of annealing. After ageing at 600°C for 500 h, some Laves phases were observed in delta ferrite which is regarded as a favourable nucleation site. In the meantime, its precipitation resulted in the reduction of dissolved W and Mo in the matrix.
“…Weld metal from classic filler metal for 7CrMoVTiB10-10 steel, 10CrMo9-10 steel and nickel base filler metals were investigated by the dilatometry. Interpretation of dilatometric diagrams can assist studies of CCT diagrams [22][23][24][25], CHT diagrams [26][27] and CTE (coefficient of thermal expansion) [28]. In this investigation coefficients of thermal expansion of P 24-IG (designated to 7CrMoVTiB10-10 steel), CMS-IG (designated to 10CrMo9-10 steel) and EPRI P87 weld metals were investigated.…”
Section: Materials and Experimental Proceduresmentioning
Gas Tungsten Arc butt welded joints of tubes of 7CrMoVTiB10-10 made using bainitic-martensitic P 24-IG filler metal were found to be susceptible to root cracking. This was avoided by using the CMS-IG filler metal and austenitic EPRI P87 filler metal. Detailed coefficient of thermal expansion analysis for both filler metals was performed. Unfortunately, CMS-IG filler metal is characterized by a lower creep rupture strength than P 24-IG. For this reason, the joints were produced by the 141 method with using two filler metals: P 24- IG and EPRI P87. All the welded joints was characterized by the B quality level. Macrostructural, microstructural and hardness data for both welded joints are presented. The standard requirement, < 350 HV10, was marginally not met and was achieved through post weld heat treatment.
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