Effect of volume fraction of (Cr, Fe)7C3 carbides on corrosion resistance of the Fe-Cr-C hardfacing alloys at Cr/C=6

In this investigation, three different chemical compositions of Fe-Cr-C alloys were fabricated on AISI 1010 steel substrates by gas tungsten arc welding (GTAW). The optical emission spectroscopy (OES), optical microscopy (OM), scanning electron microscopy (SEM), techniques and corrosion test were used for determining chemical composition studying the microstructure and corrosion behavior of the Fe-Cr-C alloys. The OM and SEM results show that the microstructure of these alloys consisted of (Cr,Fe)7C3 carbides with austenite, and by increasing of the carbon and chromium content in hardfacing alloys, the volume fraction of (Cr,Fe)7C3 carbides in microstructure was increased. The polarization curves of the corrosion tests show that the increase of the volume fraction of (Cr,Fe)7C3 carbides in the microstructure promotes the corrosion resistance of the Fe-Cr-C hardfacing alloys. The corrosion mechanism of the Fe-Cr-C hardfacing alloys was intergranular and galvanic corrosion

Effect of volume fraction of (Cr, Fe)7C3 carbides on corrosion resistance of the Fe-Cr-C hardfacing alloys at Cr/C=6

In this investigation, three different chemical compositions of Fe-Cr-C alloys were fabricated on AISI 1010 steel substrates by gas tungsten arc welding (GTAW). The optical emission spectroscopy (OES), optical microscopy (OM), scanning electron microscopy (SEM), techniques and corrosion test were used for determining chemical composition studying the microstructure and corrosion behavior of the Fe-Cr-C alloys. The OM and SEM results show that the microstructure of these alloys consisted of (Cr,Fe)7C3 carbides with austenite, and by increasing of the carbon and chromium content in hardfacing alloys, the volume fraction of (Cr,Fe)7C3 carbides in microstructure was increased. The polarization curves of the corrosion tests show that the increase of the volume fraction of (Cr,Fe)7C3 carbides in the microstructure promotes the corrosion resistance of the Fe-Cr-C hardfacing alloys. The corrosion mechanism of the Fe-Cr-C hardfacing alloys was intergranular and galvanic corrosion

Microstructure and mechanical properties of friction stir welded ferrite-martensite DP700 steel

In the present work, friction stir welding technique was applied on 2 mm thick ferrite-martensite DP700 steel sheets at rotational speeds of 600, 800 and 1000 rpm. The microstructure and mechanical properties of the welds were evaluated. It was found that Zener-Hollomon parameter decreased with increasing rotational speed that leads to grain coarsening in the stir zone. It was also found that increment of rotational speed increased softening phenomenon in sub-critical heat affected zone. The results also showed that the presence of WC particles in the stir zone, which was due to the tool wear, as well as formation of a soft ferrite band degrade the tensile properties at rotational speed of 600 rpm while HAZ softening was responsible for reduction of strength and ductility in conditions of 800 and 1000 rpm

Effect of minor Zr addition on γ′ and η phase precipitation and tensile properties of A286 superalloy

147-152In this study, the mechanisms of Zr on microstructure and tensile properties of A286 Fe-based superalloy were investigated. Cellular η phases precipitated homogenous at approximately all the grain boundaries in the modified Zr-A286 superalloy but heterogeneous in Zr-free alloy. Detailed microstructural analysis revealed that with the addition of Zr to the alloy; the grain size reduced, η volume fraction decreased and the growth and dissolution of γ′ phase accelerated. The mechanism of Zr in Ni and Fe-based superalloys is different. The mechanism in Fe-based superalloy is segregation of Zr at grain boundaries and occupation of Ti sites for η phase formation. In Ni based superalloy, Zr stabilizes the γ′ phase and retards the γ′ to η transformation. Zr addition led to improvement of room temperature tensile strength by replacement of the primary relatively smooth grain boundaries by new jagged grain boundaries after the η phase precipitation

Presenting a model of managerial practical wisdom in hospitals

References This qualitative study was conducted to provide a model of managerial practical wisdom in public hospitals in order to define the components affecting managerial practical wisdom, development strategies and its results in hospitals based on interpretive paradigm using Grounded strategy and content analysis technique and based on paradigm model of Corbin and Strauss (2008). To this end, semi-structured interviews were conducted with 21 hospital managers, professors and experts in the field of health care management. The basic themes of the interviews during the data analysis and coding stage identify the central class, causal, contextual, intervening factors, strategies and consequences of managerial practical wisdom in the form of a paradigm model and finally to create Grounded theory about managerial practical wisdom in these hospitals. Accordingly, the dimensions and components of practical wisdom among the managers of the mentioned hospitals were cognitive abilities and managerial competencies, factors affecting its development including individual factors (personal experiences, personality pattern, and individual values) and organizational factors (spirituality at work, organizational values and organizational will). Moreover, the results of developing this type of wisdom among the mentioned managers can be categorized as individual results (mental and psychological well-being), organizational results (improving service quality, stakeholder satisfaction, organizational dynamism and agility, organizational vitality and organizational citizenship behaviors) and social outcomes (social capital development). These results can be used in the creation and development of quantitative tools for measuring managerial practical wisdom and as a qualitative complement in evaluating the quality of decisions among hospital managers

Effect of Austenitizing Temperature on Mechanical Properties of the Mixed Bainite - Martensite Microstructure in CrMoV Steel

<div><p>The effect of austenitizing temperature on mechanical properties of the mixed bainite - martensite microstructure in CrMoV steel was studied in the present work. The result showed that at low austenitizing temperature (910°C - 1000°C), the mixed microstructures containing 12-28% volume fraction of lower bainite showed higher yield and tensile strength than fully martensitic microstructure. The partitioning of the prior austenite grain by lower bainite was found to cause a refinement of the martensite packet size. In addition the strength of the lower bainite in the mixed microstructure is enhanced by plastic constraint induced by the surrounding stronger martensite. By increasing the austenitizing temperature from 1000°C to 1200°C (40min), the YS, UTS, %EL, %RA and CVN impact energy decreased for all samples. This is attributed mainly to the increase in austenite grain size and width of bainite sheaves.</p></div