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Underwater friction-stir welding of a stir-cast AA6061-SiC metal matrix composite: optimization of the process parameters, microstructural characterization, and mechanical properties

Sabry Ibrahim, Hewidy A. M.

Materials Science Poland

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2022

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Vol. 40, No. 1

101--115

EN

It is an underlying fact for the case of the joining process especially welding to have optimized parameters to achieve joints with outstanding mechanical characteristics. In the current article, using stir-cast aluminum-based alloy (Al 6061) is stir-cast with Al 6061/5%wt. silicon carbide, Al 6061/10%wt. silicon carbide, and Al 6061/18%wt. silicon carbide was welded using an underwater friction-stir welding process. Optimum welding parameters [namely, tool rotating speed (N), welding speed (S), and silicon carbide (SiC)] are investigated using analysis of variance (ANOVA) and response surface methodology (RSM) statistical approaches. High ultimate tensile strength and microhardness were set as required characteristics of quality welds. Since there are two responses and two objectives, multiple-criteria decision-making approach-response surface methodology was performed alongside ANOVA. Optimal parameters from these statistical approaches are converged to a tool rotating speed of 1,736.36 rpm, a welding speed of 11.58 mm/min, and a SiC of 16.67%, respectively. For the current inquiry, the computed ultimate tensile strength and microhardness are 984 MPa and 89.9 HV, respectively, and these values are congruent with the findings of effectiveness studies. It is deduced from this study that the optimal parameters are convergent irrespective of the two used techniques for the investigated experimental data.

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Study on Improvement of Surface Properties of Low Carbon Steel Using Laser Cladding

Kim Cheol-Woo, Yoo Hyo-Sang, Jeon Jae-Yeol, Cho Kyun-Taek, Choi Se-Weon

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

1033--1036

EN

Laser cladding is a method that can be applied to repair the crack and break on the mold and die surfaces, as well as generate new attributes on the surface to improve toughness, hardness, and corrosion resistance. It is used to extend the life of the mold. It also has the advantages of superior bonding strength and precision coating on a local area compared with the conventional thermal spraying technology. In this study, we investigated the effect of cladding on low carbon alloy steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), which showed high hardness on the die surface. The process conditions were performed in an argon atmosphere using a diode laser source specialized for 900-1070 nm, and the output conditions were 5, 6, and 10 kW, respectively. After the cladding was completed, the surface coating layer’s shape, the hardness according to the cross-section’s thickness, and the microstructure were analyzed.

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Fracture toughness of advanced alumina ceramics and alumina matrix composites used for cutting tool edges

Szutkowska M.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 54, nr 2

202--210

EN

Purpose: Specific characteristics in fracture toughness measurements of advanced alumina ceramics and alumina matrix composites with particular reference to α-Al2O3, Al2O3-ZrO2, A2O3-ZrO2-TiC and AI2O3-Ti(C,N) has been presented. Design/methodology/approach: The present study reports fracture toughness obtained by means of the conventional method and direct measurements of the Vickers crack length (DCM method) of selected tool ceramics based on alumina: pure alumina, alumina-zirconia composite with unstabilized and stabilized zirconia, alumina-zirconia composite with addition of TiC and alumina-nitride-carbide titanium composite with 2wt% of zirconia. Specimens were prepared from submicro-scale trade powders. Vicker’s hardness (HV1), fracture toughness (KIC) at room temperature, the indentation fracture toughness, Young’s modulus and apparent density were also evaluated. The microstructure was observed by means of scanning electron microscopy (SEM). Findings: The lowest value of KIC is revealed by pure alumina ceramics. The addition of (10 wt%) unstabilized zirconia to alumina or a small amount (5 wt%) of TiC to alumina-zirconia composite improve fracture toughness of these ceramics in comparison to alumina ceramics. Alumina ceramics and alumina-zirconia ceramics reveal the pronounced character of R-curve because of an increasing dependence on crack growth resistance with crack extension as opposed to the titanium carbide-nitride reinforced composite based on alumina. R-curve has not been observed for this composite. Practical implications: The results show the method of fracture toughness improvement of alumina tool ceramics. Originality/value: Taking into account the values of fracture toughness a rational use of existing ceramic tools should be expected.

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Selected mechanical properties and microstructure of Al2O3ZrO2nano ceramic composites

Szutkowska M., Smuk B., Kalinka A., Czechowski K., Bućko M., Boniecki M.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 48, nr 1

58--63

EN

Purpose: Basic mechanical properties of the studied tool materials and microstructure of alumina-zirconia ceramic composites with fraction of nanopowders have been presented. Design/methodology/approach: The present study reports selected properties obtained by reinforcing Al2O3 with 15 wt% ZrO2 (partially stabilized with Y2O3-Y5) and, non-stabilized zirconia. Specimens were prepared based on submicro- and nano-scale trade powders. Vickers hardness (HV1), wear resistance and fracture toughness (KIC) at room and elevated temperatures characteristic for tool work were evaluated. Microstructure was observed by means of a scanning electron microscopy (SEM). Preliminary industrial cutting tests in the turning of higher-quality carbon steel C45 grade were carried out. Findings: The addition of nanopowders does not result in a significant improvement in fracture toughness at room temperature. A reduction in fracture toughness of KIC(ET) by approximately 20% is observed at elevated temperature (1073 K) for the specimen only with submicro powders in comparison to that at room temperature. Addition of the powder mixture in submicron and nano scale size reveals the minor reduction of fracture toughness (up to 10%) at elevated temperature. Practical implications: The results show that using of powders in submicron and nano scale size not improve the tool life but influences the fracture toughness et elevated temperatures. Originality/value: The results of the presented investigations allow rational use of existing ceramic tools.