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A medium carbon steel 34SiMn2CrNiMo was designed and fabricated, and the relationships between processing, microstructures and mechanical properties were established through microstructure characterization and mechanical properties testing on the quenching and partitioning(Q&P) heat-treated samples. Based on the experiment results of thermal expansion transformation behavior, the effects of quenching temperature TQ, heating approach, partitioning temperature TP and partitioning time tP on microstructures evolution were investigated and mechanism of strength and toughness was illuminated as well. The results show that multiphase microstructures of martensite and retained austenite can be obtained by means of Q&P processing, as a result the match of strength and plasticity is greatly improved. In the optimal treatment state, the retained austenite volume fraction is about 24%, the yield strength is 1053 MPa, the tensile strength is 1607 MPa, the elongation is 24.9%, and the product of strength and elongation(PSE) is 40.0 GPa·%. To avoid forming the blocky secondary martensite, the best quenching temperature has to be set at least 150 ℃ below martensitic transformation starting temperature Ms. More retained austenite can be achieved by slow heating than fast heating upon partitioning after the steel is incompletely quenched, the plasticity and toughness are improved apparently. The microstructures and properties of Q&P treated steel keep relatively stable with prolonged duration when it is partitioned at 400 ℃. However, the volume fraction of retained austenite decreases with tP at 450 ℃, leading the yield strength and elongation decrease simultaneously.

Objective: In order to solve the problem of poor stability, high cost and small gas flow of ternary gas mixing equipment. Methods: A ternary gas mixing system based on the ideal gas law and Dalton's law of partial pressure was proposed, and the system calculated errors and adjusted parameters by the designed algorithm, and adopted the connection of cylinder, sensor and so on. Results: After adjusting the mixing according to the relative deviation, the average relative deviation of the gas concentration of CO2 and O2 was 0.86% and 0.75% respectively, and the gas concentration accuracy met the technical requirements of ＜1%, and the high-precision gas mixing of the ternary gas can be better achieved. Conclusion: The system can realize rapid and stepless regulation of ternary gas, and high-precision continuous mixing.

The shape of a hot rolled strip is a main indicator of its quality, and camber is a significant defect arising from problems in shape quality. Differences in the bearing clearance of the two sides of a rough mill can cause a crossed roller, which leads an imbalance in the rolling force and, thereby, camber. A camber defect adversely affects product quality and the stability of the subsequent finish-rolling production process. The simulation and control of asymmetric shapes is one of the hottest topics in the field of modern strip rolling. To solve this problem and enhance the quality and precision of the strips produced, exploring and analyzing the problem of camber in hot rough rolling is necessary. This study investigated the generation of camber in the 1580 mm roughing mill R2 of a steel plant during the hot-continuous-rolling process. This paper established a three-dimensional elastic-plastic dynamic coupling model of the rolls and slab using the finite element (FE) analysis software ABAQUS/Explicit. In addition, the paper used a data analysis method based on the node-set coordinate output. By balancing the relationship between computational precision and efficiency, the study found the FE model to run stably. Using the proposed model, the paper systematically investigated the influence of cross position and angle on the camber, slab wedge, and amount of rolling force under different conditions. Based on the FE results, the paper then characterized the influence law for the occurrence of a cross roll with respect to bearing clearance and slab camber. Numerical examples demonstrate that the relationship between the camber and cross-angle position is linear, and that between the slab camber and clearance is a quadratic curve.

A new type of silica/MgCl2 composites was synthesized by the impregnation method. The effects of the pore size and particle size of silica gel, the MgCl2 concentration, and the temperature and RH of the adsorption environment on the adsorption performance of silica gel/MgCl2 composite adsorbent were analyzed. Experiments show that the adsorption capacity of the composite adsorbents is proportional to the pore size of silica gel and inversely proportional to the particle size of silica gel. The equilibrium adsorption capacities of SG-A/M20,SG-B/M20, SG-C/M20 are 0.25, 0.37 and 0.39 g/g at 25 °C, 50% RH, respectively; at 25 °C, 35% RH, the equilibrium adsorption capacities of SG-D/M20, SG-A/M20, and SG-E/M20 are 0.21,0.16, and 0.14 g/g, respectively. When the RH is 35% ~ 80%, the adsorption amount of the composite adsorbent increases with the increase of RH, and the adsorption amount of the composite adsorbent increases with the temperature increase and then decreases. At 25 °C and RH 80%, SG-B/M20 achieved maximum adsorption of 0.58 g/g. The desorption rate of the composite adsorbent is more than 98% when at 110 °C for 90 min. SG-B/M20 and SG-C/M20 have good cycling stability, and the decrease in adsorption capacity is less than 0. 03 g/g after 8 adsorption cycles. The water vapor adsorption performance of silica geZMgCl2 composite adsorbent was explored to provide data reference for the application of silica-based composite materials in the field of air-water extraction. [ABSTRACT FROM AUTHOR]

In this paper, slump-preserving polycarboxylate superplasticizer (GPEG-PCE) was synthesized by free radical copoly merization reaction by ethylene glycol monovinyl polyethylene glycol ether (GPEG), acrylic acid, hydroxyethyl acrylate, and the redox system is hydrogen peroxide/E51 and molecular mass regulator mercappropylic acid (MPA). Discuss the effect of raw material ratio and synthesis process on its performance. The test results showed that the best reaction process parameters of GPEG-PCE are: the initial temperature is 20 °C, the ratio of acid to ether is 1.6, the ratio of ester to ether is 3.6, and the amount of initiator (H2O2) and molecular weight regulator (MPA) are 0.40% and 0.63% of macromonomer, respectively. The reaction time is 1 h. The synthesized GPEG-PCE has better dispersibility and slump retention than the slump-retaining polycarboxylate superplasticizer synthesized by HPEG/TPEG polyether monomer. GPEG-PCE and ordinary polycarboxylate superplasticizer are compounded and applied to concrete in a certain proportion, which can make the concrete slumps slightly increased within 3 h. [ABSTRACT FROM AUTHOR]

Wood-plastic materials were used as one of the main components of small prefabricated buildings, and the connection methods of structural units, wall units and roof units were introduced in this research. After the design of aluminum-plastic co-extruded beams and columns connectors in the structural elements, the beams and columns could be quickly installed. In the wall units, the square steel wall column was used as the wall connection node. The nodes could realize the unification of mechanical properties and aesthetics. The modular asphalt shingle could be used in roof unit, which simplified the construction steps. Through design of the three unit above mentioned, quick installation by non-professionals can be realized, and the structural system can be applied to small prefabricated buildings such as tool room, guard room and snack bar. [ABSTRACT FROM AUTHOR]

According to performance of the blind channel identification algorithms based on second-order statistics deteriorates under the small received data and is sensitive to the error of channel order. This paper proposes an improved blind channel identificattion algorithm based on FFT, This algorithm is expoliting the property of the MCR algorithm requiring minimum redundancy information to obtain the channel vector,then effectively reduces the computational complexity of the original algorithm( BI-FFT) but the performance is quite. It has been found that the extra estimated channel common zeros introduced by overestimating the channel order based on FFT-MCR algorithm are gathered around the unit circle, at the same time puts forward R-FFT-MCR algorithm that is robustness to channel order overestimation, We can search the common zeros around the unit circle through the idea of clustering, remove them and realize the correct channel estimation. Theoretical analysis and simulation results verify the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]