Fe-6.5%Si钢极薄带的试制

 为了研究Fe-6.5%Si钢极薄带的制备工艺,并获得良好的产品磁性能,以薄带铸轧试验机制备的6.5%Si钢铸带为原料,分别采用一次温轧法、二次温轧法和基于应变诱导无序(DID)原理的高硅钢室温冷轧3种工艺制备出厚度为0.1 mm的Fe-6.5%Si钢。分析结果显示,一次温轧法退火后以高强度γ织构为主,由于压下率达到90%,形变储能高,晶粒尺寸最大,铁损最低,同时磁感也最低;二次温轧的退火板除了γ织构外,还有较强的η织构,故其磁感值高于一次温轧法,该方法得到的6.5%Si钢薄带综合磁性能最优,但生产成本高,效率低;基于DID原理,对6.5%Si钢热轧板在温度为300～450 ℃、压下率为45%～65%的条件下进行温轧,实现了6.5%Si钢软化,随后可将6.5%Si钢室温冷轧至0.1 mm,此时温轧板和冷轧板内部有序相消失,基体变成无序态;室温冷轧板退火后晶粒更细,铁损略有升高。此外,室温冷轧可促进{111}<112>形变晶粒在冷轧剪切带中形核形成有利织构,因此磁感值得到更大提升;采用DID原理进行室温冷轧,效率较高,后续可通过优化退火工艺使其进一步降低铁损,该方法为薄带铸轧工艺批量生产磁性能优异的6.5%Si钢极薄带提供技术参考。     

热轧酸洗深冲钢板组织和性能及其应用

热轧酸洗深冲钢板采用超低碳和钛微合金化等工艺 ,获得渗碳体含量极少的等轴铁素体组织 ,伸长率和杯突值高 ,实物质量达到冷轧深冲钢 St1 4的水平 ,是武钢开发的“以热代冷”即以热轧钢板代替部分冷轧钢板的新一代系列深冲钢板之一。     

薄带铸轧流程制备含钇3% Si取向硅钢的组织和织构研究

通过50 kg真空感应炉冶炼,用常规流程和薄带铸轧两种工艺分别在实验室制备了含稀土钇的3%Si取向硅钢。薄带铸轧浇注温度1530℃,轧制速率0.3 m/s,铸带厚度2.5 mm。常规流程为80 mm铸坯加热温度1150℃,热轧板厚度2.4 mm,终轧温度935℃。采用扫描电镜(SEM)和电子探针(EPMA)研究了钢中夹杂物成分、形貌、数量、尺寸和分布;利用光学显微镜(OM)和电子背散射衍射(EBSD)分析了硅钢铸带、热轧板、0.3 mm冷轧板、870℃7 min和1100℃10 min再结晶退火板组织和织构。实验结果表明：与常规流程相比,薄带铸轧硅钢一次再结晶后晶粒较细小,且γ织构强度达到17,但是二次再结晶后晶粒尺寸不均匀,平均晶粒尺寸为61μm,部分Goss取向晶粒尺寸达到1 mm以上。原因为细小的含钇夹杂物数量过多,且分布不均匀,夹杂物聚集的区域晶粒长大受到明显抑制。常规流程生产的含钇硅钢二次再结晶热处理后晶粒均匀长大,平均晶粒尺寸为102μm,没有形成明显的Goss织构。     

CSP工艺冷轧薄板盐浴退火再结晶实验

 研究了以CSP工艺热轧板卷为原料的冷轧薄板在盐浴退火过程中的再结晶行为,通过显微组织、显微硬度及电子背散射衍射技术观察、分析揭示了再结晶的规律,结果表明,CSP工艺冷轧薄板经盐浴退火后的再结晶组织为等轴状晶粒;在相同温度下盐浴退火,冷轧压下率较大时,完成再结晶所需的保温时间较短,再结晶晶粒细小。     

铁素体不锈钢铸轧薄带凝固组织对冷轧退火带晶粒簇的影响

 研究了Cr17铁素体不锈钢铸轧薄带凝固组织对其冷轧退火带晶粒簇、成形性和皱折特性的影响。利用电子背散射衍射技术对Cr17铁素体不锈钢铸轧薄带及相应的冷轧退火带进行了显微织构分析。结果表明：①Cr17铁素体不锈钢铸轧薄带冷轧退火带的晶粒簇依赖于初始铸轧薄带的凝固组织类型;②柱状晶组织的铸轧薄带具有显著的{001}∥ND晶体取向特征,而等轴晶组织的铸轧薄带晶体取向随机、分散;③等轴晶组织铸轧薄带比柱状晶组织铸轧薄带的冷轧退火带具有更少的{001}<110>晶粒簇和更多的{111}<112>、{111}<110>晶粒簇;④铸轧薄带的等轴晶组织比柱状晶组织有利于提高冷轧退火带的成形和抗皱性能。     

Analysis of Microstructure Effects on Edge Crack of Thin Strip During Cold Rolling

Edge cracks in cold rolling of the thin strip affect the strip quality and productivity significantly. In this study, an experimental and mechanical investigation on microstructures has been carried out to study the edge crack formation during cold rolling of the thin strip. The effects of the feed material microstructures on the edge crack evolution were studied employing optical microscopy and scanning electron microscopy (SEM). Experimental observation indicates that fine grain occurs in hot-rolled microstructure and coarse grain is produced in ferritic rolled microstructure. Different grain sizes affect significantly the formation mechanics of the microcrack, crack initiation, and orientation of crack extension. The grain size and grain boundaries effects on crack retardation are discussed also during edge crack initiation. During the crack growth in coarse grain, most edge crack tips will blunt, which improves the crack toughness by causing less stress concentration. Overall, the fine microstructure shows a good crack initiation resistance, whereas the coarse microstructure has a better resistance to crack propagation. This research provides additional understanding of the mechanism of microstructure influence on edge crack evolution of cold strip rolling, which could be helpful for developing defect-free thin strip.     

低温加热取向硅钢组织与织构演变研究

采用OM、EBSD、XRD分析研究了含Cu低温加热取向硅钢组织、织构的演变特征,研究结果表明：热轧板中存在铁素体层和珠光体层彼此交替的带状组织,且显微组织在厚度方向上分布不均匀,热轧板中{001}〈110〉、{112}〈110〉织构以及{110}〈001〉织构在板厚方向上分布不均匀;经过冷轧后,铁素体晶粒被严重拉长,形成了沿轧向伸长的纤维状组织,冷轧板织构类型主要是α织构和γ织构;脱碳时基体发生回复再结晶,显微组织为单一的铁素体等轴晶粒,织构主要为γ织构;二次冷轧板经渗氮后织构仅从强度上有所降低,其织构类型变化不明显。成品二次再结晶组织发展比较完善,晶粒尺寸约为10~20 mm。织构类型为锋锐的Goss织构。成品磁感B800达到了1.926 T,铁损P1.7/50为1.047 W/kg。     

热轧深冲钢板的分析和应用

在对比冷轧深冲钢的基础上,分析了工业试制的热轧深冲钢板的组织和性能。研究结果表明：该钢的碳含量较低,相应的金相组织和晶粒度合适;厚度大于２ｍｍ的钢板未经冷轧和退火处理可达到与冷轧深冲钢弧相当的成型性能,是代替冷轧深冲钢板冲压汽车零件的理想材料。该钢生产工艺简单,质量稳定,具有明显的经济效益和社会效益。     

Hot direct rolling in ferrite region in extra low-carbon steel

For the first time, hot direct rolling was applied in ferrite region in the mill and the resulting quality of the cold rolled and annealed sheet steel was as good as that hot direct rolled in austenite region with respect to microstructure and mechanical properties. In case of ferrite phase rolling, microstructure of the hot strip reveals abnormal grains and deformation bands in the grains, and elongation and r value are not so good as those rolled in the austenite phase. However, these abnormal grains left no traces and appeared to be equiaxed grains like the austenite phase rolled microstructure after 75 % cold rolling and continuous annealing at 830°C. This is attributed to the deformation bands which provide nucleation sites for recrystallization during annealing so that recrystallization occurs uniformly in the matrix. (111) texture was well developed and r value thus appeared high.     

Physical Simulation of the Hot Direct Rolling of Steel

Thin slab casting and direct rolling technologies became important for hot strip production to increase the productivity, to lower the investment costs and to increase the energy efficiency. The main objective of our investigation is to gain a better understanding of the microstructural evolution starting from solidification through to the final hot rolled sheet. Small ingots were cast and direct rolled and reheated and rolled, using a thermomechanical testing machine. The differences in the recrystallization kinetics during both production routes were measured using double hit hot compression tests. In addition, multipass deformation trials were performed to reveal differences in the resulting microstructure and the grain size homogeneity. It was found, that the coarse initial microstructure before rolling become negligible after three rolling passes. This means that despite the simple and economical direct rolling similar mechanical strip properties can be obtained in comparison to conventional strip production routes.