Deformation and fracture characteristics of ferrite/bainite dual-phase steels

The deformation and fracture characteristics of a low carbon Si&ndash;Mn steel with ferrite/bainite dual&ndash;phase structure were investigated by thermo&ndash;mechanical controlled process (TMCP). The results showed that the curves of the instantaneous work&ndash;hardening factor n* value versus true strain &epsilon; are made up with three stages during uniform plastic deformation: n* value is relatively higher at stage I, decreases slowly with &epsilon; in stage II, and then decreases quickly with &epsilon; in stage III. Compared tothe equiaxed ferrite/bainite dual&ndash;phase steel, the quasi&ndash;polygonal ferrite/bainite dual&ndash;phase steel shows higher tensile strength and n*value in the low strain region. The voids or micro&ndash;cracks formed not only at ferrite&ndash;bainite interfaces but also within ferrite grains in the necked region, which can improve the property of resistance to crack propagation by reducing local stress concentration of the crack tips.<br /

Effect of equalisation time and temperatures on microstructures of simulated directly and conventionally charged V-microalloyed steels

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Effect of silicon and prior deformation of austenite on isothermal transformation in low carbon steels

Isothermal transformation (TTT) behavior of the low carbon steels with two Si contents (0.50 wt pct and 1.35 wt pct) was investigated with and without the prior deformation. The results show that Si and the prior deformation of the austenite have significant effiects on the transformation of the ferrite and bainite. The addition of Si refines the ferrite grains, accelerates the polygonal ferrite transformation and the formation of M/A constituents, leading to the improvement of the strength. The ferrite grains formed under the prior deformation of the austenite become more homogeneous and refined. However, the influence of deformation on the tensile strength of both steels is dependent on the isothermal temperatures. Thermodynamic calculation indicates that Si and prior deformation reduce the incubation time of both ferrite and bainite transformation, but the effiect is weakened by the decrease of the isothermal temperatures.<br /

Fabrication, microstructure and mechanical properties of high performance ferrite-bainite steels

Low cost ferrite and bainite(FB) steels offer the prospect of high ultimate tensile strength combined with high hole expansion ratio. The enhanced strain hardening and formabilityof FB steels were primarily associated with the fine ferrite matrix, the low residual stresses and dislocation densityand compatible deformation between both phases.This overview describes the various techniques to produce FB steels, and comparestheresulting microstructure, tensile propertiesand tretchflangeabilitywith conventional HSLA and DP steels.A new generation of ultrafine ferrite and nano-scalebainiteautomotive steelsisunder development forthe futuredemands of extremely high strength and ductilitythroughthe fabricationtechnologiesinvolvingphase transformationsandplastic deformation

Machine Learning Sorting Method of Bauxite Based on SE-Enhanced Network

A fast and accurate bauxite recognition method combining an attention module and a clustering algorithm is proposed in this paper. By introducing the K-means clustering algorithm into the YOLOv4 network and embedding the SE attention module, we calculate the corresponding anchor box value, enhance the feature learning ability of the network to bauxite, automatically learn the importance of different channel features, and improve the accuracy of bauxite target detection. In the experiment, 2189 bauxite photos were taken and screened as the target detection datasets, and the targets were divided into four categories: No. 55, No. 65, No. 70, and Nos. 72–73. By selecting the category volume balanced datasets, the optimal YOLOv4 network model was obtained after training 7000 times, so that the average accuracy of bauxite sorting reached 99%, and the reasoning speed was better than 0.05 s. Realizing the high-speed and high-precision sorting of bauxite greatly improves the mining efficiency and accuracy of the bauxite industry. At the same time, the model provides key technical support for the practical application of the same type of engineering

Semantic Point Cloud Segmentation Using Fast Deep Neural Network and DCRF

Accurate segmentation of entity categories is the critical step for 3D scene understanding. This paper presents a fast deep neural network model with Dense Conditional Random Field (DCRF) as a post-processing method, which can perform accurate semantic segmentation for 3D point cloud scene. On this basis, a compact but flexible framework is introduced for performing segmentation to the semantics of point clouds concurrently, contribute to more precise segmentation. Moreover, based on semantics labels, a novel DCRF model is elaborated to refine the result of segmentation. Besides, without any sacrifice to accuracy, we apply optimization to the original data of the point cloud, allowing the network to handle fewer data. In the experiment, our proposed method is conducted comprehensively through four evaluation indicators, proving the superiority of our method

Effects of Climate Warming on the Potential Northern Planting Boundaries of Three Main Grain Crops in China

The production of wheat, maize and rice accounts for more than 90% of the total grain production of China. Assessing the impact of climate warming on suitable planting regions, especially the potential northern planting boundaries of these crops, is therefore critical to help guide agricultural policymaking and further maintain food security. In this study, we analyzed the effect of climate warming on the potential northern planting boundaries of three specific crops (winter wheat, spring maize, double and triple rice cropping systems) during two time periods (1961–1990 and 1991–2020) using meteorological data from 2437 national weather stations. Results show that the potential planting boundaries of these crops present a northward movement and a westward expansion during the time period of 1991–2020 under the background of temperature increase compared with the time period of 1961–1990. Moreover, the boundaries of winter wheat and spring maize also show a trend of expansion to high-altitude areas (e.g., the Qinghai–Tibet Plateau). The average moving distance of these crops ranged from 20 km to 300 km. In general, the potential planting boundaries of winter wheat, spring maize, double and triple rice cropping systems changed significantly due to climate warming, and the suitable planting area was increased. Our study aims to provide a more recent and accurate result than those of previous studies, which is expected to strengthen our understanding of the effect of climate change on the potential northern planting boundaries of the three main grain crops in China

Effects of Climate Warming on the Potential Northern Planting Boundaries of Three Main Grain Crops in China

The production of wheat, maize and rice accounts for more than 90% of the total grain production of China. Assessing the impact of climate warming on suitable planting regions, especially the potential northern planting boundaries of these crops, is therefore critical to help guide agricultural policymaking and further maintain food security. In this study, we analyzed the effect of climate warming on the potential northern planting boundaries of three specific crops (winter wheat, spring maize, double and triple rice cropping systems) during two time periods (1961&ndash;1990 and 1991&ndash;2020) using meteorological data from 2437 national weather stations. Results show that the potential planting boundaries of these crops present a northward movement and a westward expansion during the time period of 1991&ndash;2020 under the background of temperature increase compared with the time period of 1961&ndash;1990. Moreover, the boundaries of winter wheat and spring maize also show a trend of expansion to high-altitude areas (e.g., the Qinghai&ndash;Tibet Plateau). The average moving distance of these crops ranged from 20 km to 300 km. In general, the potential planting boundaries of winter wheat, spring maize, double and triple rice cropping systems changed significantly due to climate warming, and the suitable planting area was increased. Our study aims to provide a more recent and accurate result than those of previous studies, which is expected to strengthen our understanding of the effect of climate change on the potential northern planting boundaries of the three main grain crops in China