Zhenshan CUI
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Bingye XU
材料科学技术（英文）
A generalized mathematical model is developed to predict the changes of temperature, rolling pressure, strain, strain rate, and austenite grain size for plate hot rolling and cooling processes. The model is established mainly by incorporating analytical and numerical method for differential equations under complicated boundary conditions. An industrial rolling and cooling process of plate is simulated by the model, in which the thickness of steel Q235B plate is rolled from initial 200 mm to final 12 mm by 13-passes in a two-high mill. The calculated results are in good agreement with measured data. Different from FEM simulation, the model takes very short time in calculation and makes the influence of rolling passes on precision to be very slight.
关键词:
Hot rolling
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王晓峰
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赵九洲
金属学报
本文采用喷射成形和沉积坯热轧的方法成功制备了AZ91合金，测试了合金的力学性能，分析了合金的强化机理。实验结果表明：喷射成形的镁合金坯晶粒细小，组织均匀，第二相化合物Mg17Al12数量较少，表现出良好的塑性变形能力，道次变形量在20%左右，两次退火间的总变形量可以达到50%。经80%热轧变形后，合金完全致密化。变形使合金晶粒细化，力学性能显著提高。合金轧制后基体中仍保持很高的固溶度，经T5处理后，合金性能进一步提高。
关键词:
镁合金
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Spray forming
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Hot rolling
Guangmin LUO
材料科学技术（英文）
The graphitization behavior of ultrahigh carbon steels containing Si in hot rolling processes was investigated. The graphite stringers went mostly through the small pores and generally paralleled to the rolling direction. The influence of alloy elements on graphitization was estimated based on thermodynamics, which showed that Si content was important for graphitization. Graphite stringers nucleated at small pores and grew with carbon diffusion during hot rolling. Alloy contents, pores and hot deformation at γ+Fe3C phase range were the key factors for the formation of graphite. The probable effect of deformation on graphite formation during hot rolling was discussed in this paper.
关键词:
Graphitization
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Xiaochun SHA
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Chunli MO
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Dianzhong LI
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Yiyi LI
材料科学技术（英文）
Based on hot rolling production line of strip steel, the off-line in-house software, termed as ROLLAN (Rolling Analysis), is developed. The code is mainly used to predict the evolution of temperature, rolling force, fraction and grain size of recrystallization, fraction and grain size of phase transformation and final mechanical properties. Almost all the processing parameters affecting microstructure and mechanical properties in the schedule from reheating to the coiling process are considered in detail. Self-learning coefficient is adopted to adjust the deviation between predicted and measured temperatures, such as roughing exit temperature (RT2), finishing exit temperature (FT7) and coiling temperature (CT). Due to the application of low-speed-threading, increasing-speed-rolling and decreasing-speed-delivery process during finishing rolling and different cooling condition, after coiling the thermal-mechanical history of different position, along strip longitudinal direction is different resulting in inhomogeneous mechanical properties. So the segments are divided along longitudinal direction to identify the variation of microstructure and mechanical properties. An example of plain carbon strip steel Q235 with various thickness is used to compare the calculated mechanical properties with measured ones. For the specific grade of Q235 , the maximum deviation of tensile strength is less than 10.3 MPa, the yield strength is less than 13.2 MPa, and elongation is less than 1.99%. Further work will focus on the on-line application and consider the effect of macrosegregation and sulfur content of cast slab.
关键词:
Microstructural evolution
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