莱钢特钢厂50 t UHP-EAF(热装铁水比≥50%)+LF(VD)冶炼的Q235D钢(0.10%～0.17%C)260mm×300 mm的连铸坯轧制成直径Φ150 mm圆钢后,钢材表面出现裂纹。分析表明,钢的包晶点的碳当量[C_1]与钢中实际碳含量[C]之间的差别△C越大,亚包晶...莱钢特钢厂50 t UHP-EAF(热装铁水比≥50%)+LF(VD)冶炼的Q235D钢(0.10%～0.17%C)260mm×300 mm的连铸坯轧制成直径Φ150 mm圆钢后,钢材表面出现裂纹。分析表明,钢的包晶点的碳当量[C_1]与钢中实际碳含量[C]之间的差别△C越大,亚包晶钢Q235D钢材废品率越高。实践表明,控制0.15%～0.17%[C]使△C<0.015%,钢液过热度20～30℃,结合降低结晶器冷却水流量和二冷区冷却强度,低拉速,使成品材表面质量合格率在99.3%以上。展开更多
The internal friction behavior of Al green power compact duxing the sintering process was studied as a function of temperature. The internal friction measurements were performed from room temperature to 600 °C. T...The internal friction behavior of Al green power compact duxing the sintering process was studied as a function of temperature. The internal friction measurements were performed from room temperature to 600 °C. Two typical internal friction peaks were detected corresponding to heating and cooling processes, respectively. The heating peak corresponds to a recrystallization process of deformed Al particles, which is influenced by many extrinsic parameters, such as measuring frequency, strain amplitude, heating rate, power particle size and compacting pressure. However, the intrinsic nature of the peak is originated from the micro-sliding of the weak-bonding interfaces between Al particles and increased dislocation density induced in compressing. The cooling peak with the activation energy of (1.64±0.06) eV is associated with the grain boundary relaxation, which can be interpreted as the viscous sliding of grain boundaries. The similar phenomena are also found in the Mg green powder compact.展开更多
A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of...A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30 ℃and 15 ℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 ram, respectively. The surface temperature without nickel layers is depressed by 10 ℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5 ℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.展开更多
文摘莱钢特钢厂50 t UHP-EAF(热装铁水比≥50%)+LF(VD)冶炼的Q235D钢(0.10%～0.17%C)260mm×300 mm的连铸坯轧制成直径Φ150 mm圆钢后,钢材表面出现裂纹。分析表明,钢的包晶点的碳当量[C_1]与钢中实际碳含量[C]之间的差别△C越大,亚包晶钢Q235D钢材废品率越高。实践表明,控制0.15%～0.17%[C]使△C<0.015%,钢液过热度20～30℃,结合降低结晶器冷却水流量和二冷区冷却强度,低拉速,使成品材表面质量合格率在99.3%以上。
基金Project(51301150)supported by the National Natural Science Foundation of ChinaProject(2013KJXX-11)supported by the Special Program of Youth New-star of Science and Technology of Shaanxi Province,ChinaProject(Physics-2012SXTS05)supported by the High-level University Construction Special Program of Shaanxi Province,China
文摘The internal friction behavior of Al green power compact duxing the sintering process was studied as a function of temperature. The internal friction measurements were performed from room temperature to 600 °C. Two typical internal friction peaks were detected corresponding to heating and cooling processes, respectively. The heating peak corresponds to a recrystallization process of deformed Al particles, which is influenced by many extrinsic parameters, such as measuring frequency, strain amplitude, heating rate, power particle size and compacting pressure. However, the intrinsic nature of the peak is originated from the micro-sliding of the weak-bonding interfaces between Al particles and increased dislocation density induced in compressing. The cooling peak with the activation energy of (1.64±0.06) eV is associated with the grain boundary relaxation, which can be interpreted as the viscous sliding of grain boundaries. The similar phenomena are also found in the Mg green powder compact.
基金Project(51004031) supported by the National Natural Science Foundation of ChinaProject(50925415) supported by the National Outstanding Young Scientist Foundation of China+1 种基金Project(20100042120012) supported by the Special Research Fund for Doctoral Programs of Ministry of Education of ChinaProject(N090402022) supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30 ℃and 15 ℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 ram, respectively. The surface temperature without nickel layers is depressed by 10 ℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5 ℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.
