共查询到20条相似文献,搜索用时 15 毫秒
1.
通过光学显微镜、扫描电镜、能谱分析以及酸洗模拟等方法,研究了高强IF钢HC250IF表面条带缺陷的产生原因、结构特点和控制措施。结果表明,氧化铁皮沿带钢宽度方向的不均匀分布以及拉矫破碎效果不充分导致了带钢边部比中部更容易发生过酸洗。在磷元素表面富集和晶界偏聚作用下,基体晶界处优先发生选择性侵蚀,侵蚀裂纹沿晶界从表面向内部扩展,形成具有厚度差的多孔区和粗糙区结构。冷轧过程中,缺陷部位变形撕裂,产生了大量表面微裂纹,增大了局部粗糙度差异,进而在带钢边部形成条带缺陷。以优化匹配热轧和酸洗工艺参数、改善热轧带钢表面状态为基础,通过控制酸洗进程、提高酸洗质量均匀性等措施,能够有效减少这类缺陷的发生。 相似文献
2.
通过光学显微镜、扫描电镜、能谱分析以及酸洗模拟等方法,研究了高强IF钢HC250IF表面条带缺陷的产生原因、结构特点和控制措施。结果表明,氧化铁皮沿带钢宽度方向的不均匀分布以及拉矫破碎效果不充分导致了带钢边部比中部更容易发生过酸洗。在磷元素表面富集和晶界偏聚作用下,基体晶界处优先发生选择性侵蚀,侵蚀裂纹沿晶界从表面向内部扩展,形成具有厚度差的多孔区和粗糙区结构。冷轧过程中,缺陷部位变形撕裂,产生了大量表面微裂纹,增大了局部粗糙度差异,进而在带钢边部形成条带缺陷。以优化匹配热轧和酸洗工艺参数、改善热轧带钢表面状态为基础,通过控制酸洗进程、提高酸洗质量均匀性等措施,能够有效减少这类缺陷的发生。 相似文献
3.
4.
5.
目前国内外已有相关专家对变压器绕组的铜带边部精准处理进行了相关研究,但是对精准处理装备和处理技术没有涉及,本文分析了铜带边部精准处理情况,"五位一体"铜带边部处理精整处理装备的工作运行方式,该处理装置实现了对铜带边部缺陷的处理,为变压器绕组的安全稳定运行提供了技术支持。 相似文献
6.
板形是带钢质量的重要判定指标,常见的板形缺陷有边浪、中浪、1/4浪等,其实质是残余应力在带宽上的分布不均。拉伸弯曲矫直机通过张力辊组、弯曲辊组和较真辊组的共同作用,使带钢在低于屈服强度的张力作用下发生塑性延伸,从而有效消除浪形缺陷,改善板形,提高带钢质量。然而在拉伸弯曲矫直机的设计和使用过程中,对拉伸弯曲矫直机参数的调整多基于经验,缺少理论指导。为了定量分析拉伸弯曲矫直机参数对浪形缺陷的改善效果,使拉伸弯曲矫直机在实际生产中发挥更好的作用,以某1 450 mm带钢酸洗冷轧生产线上的拉伸弯曲矫直机为研究对象,使用有限元软件ANSYS/LS-DYNA基于三维弹塑性有限元法建立了拉伸弯曲矫直机模型,对拉伸弯曲矫直机矫直过程进行了模拟,分析了张力和插入深度对初始浪形分别为边浪和中浪的带钢矫直后板形的影响规律。结果表明,经过拉伸弯曲矫直的带钢浪形缺陷得到显著改善;插入深度和张力对初始浪形缺陷分别为边浪和中浪的带钢板形的影响规律一致;3个辊组中矫直辊组的插入深度是影响带钢板形的主要因素,随着矫直辊组插入深度增大,带钢矫直后板形由边浪转变为平直,且随着矫直辊插入深度进一步增大,板形又由平直转变为边浪;随着入口张力增大,带钢矫直后板形由边浪转变为中浪。 相似文献
7.
8.
Haibo Xie Zhengyi Jiang W. Y. Daniel Yuen 《Metallurgical and Materials Transactions B》2011,42(6):1244-1252
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. 相似文献
9.
10.
11.
针对新钢热连轧无取向硅钢冷轧基料XG1300WR、XG1000WR、XG800WR带钢边部"翘皮"缺陷,根据其形成机理,对影响无取向硅钢带钢边部"翘皮"缺陷的主要影响因素进行了分析。结果表明,在一定钢种成分与加热轧制工艺下,粗轧过程边部的组织形态和侧压量对带钢边部"翘皮"缺陷的发生率有较大影响。为了有效控制带钢边部"翘皮"缺陷,在钢的成分控制,加热与轧制工艺,立辊孔型以及影响粗轧板坯边部温降等方面提出了可行的改进措施。 相似文献
12.
13.
14.
文章对铜带荷叶边形成的原理进行了分析,指出剪切工艺参数影响铜带的边部质量;刀轴精度、刀具及橡胶环精度影响剪切时的水平间隙和重叠量。生产中应及时调整铜带在圆盘剪出入口的位置和铜带方向,避免荷叶边的产生。 相似文献
15.
For conventional casting processes low copper and tin contents have to be ensured in LC‐steel to avoid hot shortness. It is expected that higher cooling rates, e.g. in thin strip casting, permit higher copper and tin limits. Hot shortness occurs because of selective oxidation of the iron whereby the more noble copper is enriched at the steel‐oxide interface. A liquid metallic copper phase which wets the grain boundaries supports cracking during hot deformation. The enrichment of the liquid copper phase depends on the oxidation temperature: At low temperatures copper is solid, cannot wet the steel surface and is incorporated into the growing oxide layer. At mid temperatures (1083‐1177 °C) the copper phase is liquid, wets the grain boundaries of the steel surface and causes hot shortness. At high temperatures a liquid fayalitic slag is formed in the oxide layer if the steel contains silicon. The fayalitic phase occludes parts of the steel surface and removes copper from the steel surface; then hot shortness is reduced or even avoided. Other mechanisms to remove copper from the steel surface need the presence of Fe3O4 and Fe2O3 in the oxide layer. These iron oxides are not formed for short oxidation times where linear oxidation takes place. Diffusion of copper into the steel is too slow to reduce hot shortness if copper has an elevated concentration in the steel, e.g. 0.5 wt.‐%. Therefore, only the occlusion mechanism is of importance during linear oxidation. A model is established on the basis of these observations in order to predict an upper copper limit in dependence of the steel strip thickness (cooling behaviour) and the oxygen content in the cooling atmosphere (nitrogen‐oxygen mixture). The model is compared to experimental results from KIMAB which are presented in this issue. It is demonstrated that a copper layer thickness of 0.098 μm at the steel‐oxide interface is sufficient to cause cracks of a depth of more than 0.2 mm. For strip thicknesses below 5 mm a simple approximation can be used to predict the maximum copper content in LC‐steel to avoid hot shortness. For example, thin strip of a thickness of 2 mm will have no cracks (above 0.2 mm) even if 0.7 wt.‐% of copper is contained in the LC‐steel. For atmospheres with a reduced oxygen partial pressure even higher copper contents are possible. Tin is with short oxidation times not a problem concerning hot shortness, as shown by the KIMAB results. This may be explained by the much higher diffusivity of tin in iron compared to copper. 相似文献
16.
17.
汽车用超高强度双相钢CR550/980DP冷轧边裂问题,严重影响热轧/冷轧工序界面生产顺行,易造成冷轧机架间及连退炉内断带事故,成为超高强度双相钢生产的难题。基于高温热塑性曲线和热轧动态CCT曲线,采用对显微组织、力学性能、裂纹扩展分析等手段明确冷轧边裂产生原因。试验结果分别指出,精轧阶段带钢横向温度分布不均匀、边部温降大,导致在第Ⅲ脆性区轧制;同时,受Nb作用再结晶温度提高,边部低温区为未再结晶区轧制;当应变量超过塑性极限、轧制力超过边部热强度时,形成热轧卷边裂。边部形成细小弥散的铁素体(F)和马氏体(M)两相组织,不协调应变将导致F/M相界面产生应力集中而形成裂纹;裂纹以微孔聚集方式进行扩展,形成热轧卷无边裂-冷轧边裂现象。通过投用边部加热器和优化初轧定宽量、精轧入口温度、精轧机架间冷却水、终轧温度、卷取温度等措施,实现热轧卷边部质量改善、解决边裂问题。 相似文献
18.
19.
《钢铁研究学报(英文版)》2014
In order to find out the cause of surface microcrack on 304 austenitic stainless cold rolled coils which is produced in a steel plant of China, lots of studies have been carried out. The results indicated that the copper guide of steekle mill used in hot rolling process contacts directly with the hot rolled coil, so parts of copper melt and glued to the surface of the stainless steel plates due to a higher temperature of stainless steel plates than the copper melting temperature, which leads to deterioration of austenitic grain boundaries. Shear stress produced in the process of repeat-rolling on finishing mill induces the surface microcracks and promotes it. After changing the copper guide to the cast steel one, such kinds of surface microcracks have never appeared. 相似文献
20.
取向硅钢热轧板中织构梯度对发展完善的二次再结晶十分关键,通过添加Cu可以显著降低取向硅钢板坯加热温度,从而影响热轧板织构分布。本文利用X射线衍射仪,分析了实验室模拟薄板坯连铸连轧(TSCR)工艺的3种不同Cu含量的取向硅钢热轧板织构。结果表明:不同Cu含量热轧板表面到厚度1/4处均为弱的热轧织构,热轧板心部主要为{100}面织构;Cu含量约在0.4%时,热轧板次表层的{110}<001>织构比例最高,而热轧板心部的{100}<110>织构比例最低;Cu含量对热轧织构中{114}<110>和{001}<100>织构发展有显著影响。 相似文献