Critical assessment of models for predicting the Ms temperature of steels

Different approaches to predicting the Ms temperatures of steels are reviewed and discussed with the objective of summarising the main characteristics, advantages and difficulties of each method, mostly from a practical point of view. Empirical methods, and methods based on thermodynamics are then assessed against published data.NPL for provision of MTDATA and Neuromat for provision of the Model ManagerPeer reviewe

Rural Community, Group Identity and Martial Arts: Social Foundation of Meihuaquan

P. 18-29Meihuaquan no solo sobrevivió a cuatro dinastías sucesivas, así como a guerras y otros trastornos sociales, sino que está disfrutando de la revitalización en el contexto de la urbanización. Objetivo: ¿Cuál es la base social del renacimiento de Meihuaquan en las zonas rurales del norte de China? El enfoque de este documento es cómo este avivamiento es apoyado por instituciones sociales, especialmente la identidad grupal de Meihuaquan. Método: los métodos de este artículo incluyen el trabajo de campo de observación participante, entrevistas semiestructuradas y encuesta por cuestionario. Resultados (1) Meihuaquan ha sobrevivido a cuatro dinastías sucesivas, así como a guerras y otros trastornos sociales. (2) Desde 2006, el ambiente político ha alimentado la supervivencia y el desarrollo de Meihuaquan. Ahora, está disfrutando de un avivamiento. (3) Es un medio para enriquecer la vida personal, social y espiritual de las personas locales. (4) Meihuaquan sirve como medio de formación de identidad no solo para los hombres sino también para las mujeres. (5) Los adultos jóvenes tienen un entusiasmo similar con respecto a Meihuaquan que sus adultos mayores. (6) La conciencia cultural de los jóvenes educados es útil para el desarrollo de Meihuaquan. Conclusiones: la razón fundamental para el avivamiento de Meihuaquan es que cultivó el sentido de identidad de grupo para la población local en el norte de China. Este tipo de identidad grupal no se trata solo de las relaciones sociales, sino también de la vida espiritual; no solo aceptado por los hombres, sino también reconocido por las mujeres; no solo sentido por personas mayores, sino también apoyado por la generación más joven; No solo favorecido por los campesinos, sino también practicado por estudiantes universitarios. En resumen, Meihuaquan estableció la identidad de sus miembros, la población local y el gobierno mediante muchas estrategias, y mantuvo el equilibrio entre las tres faccionesS

Effect of Micro-Silica Addition into Electric Arc Furnace Steel Slag Eco-Efficient Concrete

ABSTRACT: Concrete produced from electric arc furnace steel slag aggregates is one of the items that is highly regarded due to its strength, environmental friendliness and cost-effectiveness. Despite the growing interest in using this type of concrete, there are still doubts about the mix proportions and addition effects of electric arc furnace steel slags. In this paper, the performance of replacing natural aggregates by electric arc furnace steel slags aggregate is comprehensively investigated and its effect on mechanical properties is analysed. The relationship between the percentage of replacement of natural aggregate using electric arc furnace steel slags aggregate in two parts of coarse aggregate and fine-grained aggregate and the effect of each of these parts on mechanical properties in concrete is investigated, which may identify the optimal mix proportions of each aggregate that help to improve the strength of the eco efficient concrete using electric arc furnace steel slags

Induced martensitic transformation during tensile test in nanostructured bainitic steels

Retained austenite in nanostructured bainite is able to undergo mechanically induced martensitic transformation. However, the link between transformation and deformation mechanisms involved makes difficult the understanding of the process. In this work, a model has been developed to assess the effect of the external stress itself on the martensite phase transformation. In addition, after a detailed initial microstructural characterization, the martensite fraction evolution during tensile deformation has been obtained by means of X-ray diffraction analyses after interrupted tensile tests in several nanostructured bainitic steels. Experimental results have been compared to the outputs of the model, as a reference. They suggests that stress partitioning between phases upon tensile deformation is promoted by isothermal transformation at lower temperatures.The authors gratefully acknowledge the support of the European Research Fund for Coal and Steel, the Spanish Ministry of Economy and Competitiveness and the Fondo Europeo de Desarrollo Regional (FEDER) for partially funding this research under the contracts RFSR-CT-2012-00017, RFSR-CT-2014-00016 and MAT2013-47460-C5-1−P respectively. LM-R also acknowledges this same Ministry for financial support with ref. FPI: BES-2011-044186.Peer Reviewe

Structural recycled aggregate concrete made with precast wastes

This paper presents the main results of the characterization of recycled aggregate concrete made with precast structural concrete wastes as a case study. The use of recycled aggregates presents two main benefits. On the one hand, there would be an economic and environmental saving because it would not need to deposit waste in landfills. On the other hand, there would be a further economic and environmental saving because it would reduce the need for natural aggregate. However, because of the need of a greater amount of cement not all degrees of substitution present advantages. The results were obtained from four degrees of substitution and different mixing proportions and methods using natural and recycled aggregates and superplasticizers. After obtaining the optimal mixing proportions, the concretes have been fully characterised performing mechanical and durability tests, the methods analysed and the results compared with the literature

Influence of Recycled Precast Concrete Aggregate on Durability of Concrete's Physical Processes

ABSTRACT: The research presented in this article analysed the influence of incorporating precast concrete waste as an alternative to coarse aggregate in self-compacting concrete to generate new precast elements. The experimental study involved the characterization of recycled aggregate and the design of the mix of the new self-compacting concrete (SCC). The experimental study evaluates the physical processes that affect the durability of concrete with percentages of incorporation such as 20%, 50% and 100% of recycled aggregate. Two types of SCC were manufactured with minimum compressive strength of 30 MPa and 45 MPa. The properties analysed were density of hardened SCC, shrinkage cracking, freeze-thaw resistance, resistance to ageing by thermal shock and abrasion resistance. The results obtained were compared with those of the control concrete, observing great capacity of the SCC under physical aggressions that affect durability. The results of this research show that it is possible to use the recycled aggregate coming from precast pieces in order to the manufacture of self-compacting recycled concrete in the same precast industry. However, high loss of proprieties occurs for a 100% substitution, while for 20% and 50%, the variations with respect to control concrete are smaller. In addition, taking advantage of this waste to incorporate it back into the production chain contributes to more sustainable construction.This research was funded by Junta de Castilla y León (Regional Government) for funding UIC-231 through project BU119P17; MINECO for funding through project BIA2014-55576-C2-1-R; FEDER (European Regional Development Funds) and LADICI

Tensile behaviour of a nanocrystalline bainitic steel containing 3 wt% silicon

Much recent work has been devoted to characterize the microstructure and mechanical properties bainitic nanostructured steels. The microstructure is developed by isothermal heat treatment at temperatures as low as 125–350 °C and adapted steel grades typically contain high carbon contents to achieve sufficient depletion of the BS–MS temperature range, and above 1.5 Si wt.% to suppress carbide formation during isothermal holding. On the latter, most of the published literature agrees on a limit of around 1.2–1.5 wt.% to suppress cementite in high carbon steels. For this reason perhaps, additions of Si significantly above this limit have not been investigated systematically in the context of nanostructured bainitic steels. The present work is concerned with the effect of up to ∼3 Si wt.% in a steel grade adapted to low temperature bainitizing. Tensile properties as compared to similar grades, though with lower Si contents, exhibited unrivalled combinations of strength and ductility, with above 21% total elongation for a UTS above 2 GPa. An attempt is made to explain the mechanical properties of this microstructure in terms of some of its most relevant and unique morphological and microstructural featuressupport of the European Research Fund for Coal and Steel and the Spanish Ministry of Science and Innovation Plan Nacional de I+D+I (2008–2011) for funding this research under the contracts RFSR-CT-2008-00022, and MAT2010-15330,also acknowledges the Spanish Ministry of Science and Innovation for financial support in the form of a PhD research grant (FPI)Peer reviewe

The influence of recycled aggregates from precast elements on the mechanical properties of structural self-compacting concrete

Recycled Aggregates (RA) from structural precast elements and the performance of Self-Compacting Concrete (SCC) containing RA in percentage substitutions of 20%, 50% and 100% are described in this paper. Three Control Concretes (CC-30, CC-37.5, CC-45) manufactured with Natural Aggregates (NA), and their corresponding Recycled Aggregate Concretes (RAC-20, RAC-50, RAC-100) are evaluated in terms of physical and mechanical properties. The in-fresh properties results (flowability, viscosity and passing ability) of the RAC were suitable for their use as SSC. Furthermore, the tests of compressive, splitting tensile and flexural strength, as well as density, porosity, water absorption, ultrasonic pulse velocity, stiffness, and both dynamic and static modulus provided results close to those of the SCC with NA, and in compliance with the requirements of current regulations. The recycling process that takes place in the precast factory supposes an economical improvement and an important contribution to global sustainability, in accordance with the concept of the circular economy.The authors wish to express their gratitude for having contributed to the financing of this research to: Junta de Castilla y León (Regional Government) for funding UIC-231 through project BU119P17; MINECO for funding through project BIA2014-55576-C2-1-R; and FEDER (European Regional Development Funds). Moreover, we are grateful to the precast concrete company Artepref for having collaborated with the present research work

Self-compacting concrete containing coarse recycled precast-concrete aggregate and its durability in marine-environment-related tests

Marine environments are extremely challenging for the long-term durability of concrete. Prior validation of concrete durability is therefore a prerequisite to guarantee its adequate performance under marine environmental conditions. In this study, the performance of Self-Compacting Concrete (SCC) with variable contents of coarse Recycled Precast-Concrete Aggregate (RPCA) and two different cement contents is assessed in terms of capillary water absorption, natural and accelerated carbonation, resistance to SO2 attack, and moist/dry performance in drinking water, marine water, and sulfate water. These tests are intended to simulate the conditions of a marine environment. In general, the results showed that an SCC containing coarse RPCA of adequate durability under marine conditions could be produced. On the one hand, porosity due to the presence of RPCA increased less as the cement content was increased, which in turn reduced water absorption and SCC carbonation. For example, the effective porosity of the SCC was reduced by 25 % between day 28 and day 180, following the addition of 100 % coarse RPCA. On the other hand, both the SO2-attack and the moist/dry tests revealed that the weight of the SCC with RPCA underwent greater variations, due to the reactions of the cementhydration products with chlorides and sulfates, as well as salt deposition. However, SCC compressive strength was never adversely affected, as the concrete strength increased up to 8 MPa after the drinking-water and the sulfate-water moist/dry tests when using RPCA. According to both Fick's and Parrot's models, the projected service life of all the mixes was over 100 years, regardless of the coarse RPCA content, making this sort of SCC a feasible option for construction in marine environments.This research work was supported by the Spanish Ministry of Universities, MICINN, AEI, EU, ERDF and NextGenerationEU/PRTR [grant numbers PID2020-113837RB-I00; 10.13039/501100011033; TED2021- 129715B-I00]; the Junta de Castilla y León (Regional Government) and ERDF [grant number UIC-231]; and, finally, the University of Burgos [grant number SUCONS, Y135.GI]