热轧低碳钢带表面氧化铁皮分析及酸洗生产实践

基于不同热轧产线生产的低碳钢带表面氧化铁皮厚度和微观结构分析,设计了酸洗实验模拟并组织了工业生产实践,结果表明:2050线相较1580线热轧温度更高、轧后冷却距离更长,导致钢带表面氧化铁皮更厚、共析转变更充分、转变组织更致密,因此钢带适宜酸洗温度更高、酸洗时间更长。根据相关理论和实践经验,对2050线热轧钢带氧化铁皮难以酸洗的问题提出了生产工艺改进建议。     

热轧酸洗板表面黑色条纹缺陷成因分析

热轧酸洗板表面存在暗黑色的条纹。通过SEM、EDS以及表面粗糙度仪对酸洗后的钢板表面形貌以及不同部位粗糙度值进行了分析,发现板面发黑的部位较为毛糙,粗糙度值较大但不存在元素的偏聚。结合对热轧板的氧化铁皮结构以及实验室模拟酸洗分析,得出了产生条纹缺陷的主要原因：氧化铁皮厚度的均匀性以及氧化铁皮与基体的结合状态。     

冷轧酸洗板板面质量改进措施

通过对热轧钢带表面氧化铁皮的成分分析和酸洗机理的研究,确定了影响酸洗效果的主要成因,即酸洗盐酸的浓度、机组速度和氧化铁皮的厚度,并对钢卷的开卷穿带速度及甩尾速度进行了攻关试验,确定了穿带速度和甩尾速度。针对不同钢板,采取不同酸洗方法,有效提高了酸洗钢带表面质量,大幅度减少了酸洗发黑钢卷,按每月减少300~400 t进行计算,可减少9万~12万元的经济损失。     

热轧400系不锈钢中厚板连续酸洗线成功酸洗

单张热轧400系不锈钢中厚板热轧后,需要经过热处理退火降低其硬度和改善组织,退火以后表面产生大量的氧化皮量,经过机械破鳞(抛丸)去除表面的大部分氧化铁皮,然后再经过酸洗将其表面剩余氧化皮去除,并使表面生成一层钝化膜。热处理退火过程中表面产生的氧化铁皮成分复杂,通过表面氧化铁皮成分的研究,在实验室配置不同浓度的酸液进行了酸洗试验,根据试验的浸泡时间转换成连续线的辊道速度,最终确定了连续酸洗线的酸洗方式以及硫酸浓度、硝酸浓度的配置,在硫酸段、混酸段的酸液温度控制以及辊道速度的调整;重点对连续酸洗线工艺酸洗机理、生产工艺质量过程控制、生产实践总结等几个方面进行了简要的介绍和分析。     

热轧结构钢氧化铁皮结构及其对酸洗质量的影响

为研究热轧结构钢氧化铁皮厚度、结构及其对酸洗质量的影响,设计了"高温、低冷速"和"低温、高冷速"两种热轧工艺,并进行了热轧结构钢的生产制备.利用光学显微镜、扫描电镜分析了带钢宽度方向上氧化铁皮的厚度分布、结构特点和带钢酸洗后的表面形貌;基于不同热轧工艺下氧化铁皮厚度、结构差异,对带钢的酸洗效果以及酸洗色差缺陷的产生机理...     

冷轧钢带表面粒状斑迹缺陷分析

针对新钢冷轧钢带表面粒状斑迹缺陷问题,运用扫描电镜和能谱仪分析冷轧钢带典型缺陷的形貌以及特征点的化学成分,结果表明:冷轧卷表面粒状斑迹缺陷是冷轧酸洗未净的氧化铁皮压入钢带所致,并对热轧的轧辊管理、除鳞系统维护、温度制度等进行优化。优化后冷轧钢带表面质量有很大改善,钢带出现粒状斑迹缺陷的比例明显下降,粒状斑迹月平均缺陷比例由原来的4.26%降至1.69%。     

热轧酸洗表面发黑的原因与改进

分析了SAPH系列热轧酸洗板表面氧化铁皮的形成机理,提出了化学成分、热轧工艺、卷取温度改进方案。优化了热轧酸洗板表面氧化铁皮的形成结构,稳定了酸洗温度及时间,提高了产品表面质量,解决了热轧酸洗板表面发黑的问题。     

冷轧酸洗钢板表面黑斑缺陷分析

针对冷轧酸洗钢板黑斑缺陷问题,对Q195、ST13钢在不同试验温度下进行了氧化铁皮的生成、冷却、酸洗试验,对试验后的试样和生产现场钢板的表面进行了微观分析。结果表明：冷轧酸洗钢板黑斑实质上是未完全酸洗掉而残存的氧化铁皮,是由热轧工艺引起;冷轧酸洗钢板黑斑主要由Fe3O4和FeP组成;温度越高,表面氧化铁皮越厚,e3O4含量越高,冷轧酸洗钢板越易产生黑斑。     

国内碳钢酸洗机组的发展及技术创新

对国内碳钢酸洗技术的发展进行了简要的介绍,主要包括减酸洗技术、无酸酸洗技术以及厚板酸洗技术。减酸洗技术主要是通过控制热轧过程中产生氧化铁皮的成分,从而达到减酸洗或免酸洗的目的;无酸酸洗技术是通过湿式喷砂这种机械除鳞的方式去除带钢表面的氧化铁皮,是近些年新推出的除鳞技术;厚板卷酸洗是采用规模化的酸洗机组取代单张板浸泡式酸洗。     

高牌号无取向硅钢酸洗工艺的研究

对比分析了高牌号无取向硅钢和碳钢热加工过程表面产生的氧化铁皮结构,在某硅钢常化酸洗生产线上,进行了一系列酸洗实验,研究了酸洗温度、酸液浓度、抛丸密度对酸洗时间和效果的影响,认为高牌号无取向硅钢表面氧化铁皮难于酸洗的原因是其特殊的结构造成的;得出了适用于高牌号无取向硅钢工业化生产的酸洗工艺参数。     

Effect of solution treatment on structure of oxide scales for 2205 duplex stainless steel

The oxide scales of 2205 duplex stainless steel plates were studied at hot- rolled state and solid- solution state by SEM, XRD and EDS. The oxide scales on the surface of 2205 duplex stainless steel are composed of a variety of oxides, such as Fe2O3, Cr2O3, FeO??Cr2O3 and NiO??Fe2O3 with spinel structure. After the solution treatment, the oxide scales on the surface changed, in the meantime, the oxidation occurred in the stainless steel substrate. The content of Cr, Ni, Mo increased in the oxides contacting with the substrate, in addition, the distribution of Cr and Ni was more evenly in the oxide scales. The content of Si, Mo increased significantly in the contacting part with the substrate. The surface of the steel plate was formed by a certain outside- in hierarchical oxide phase of Fe, Mo, Ni, Cr and Si. The stability and complexity of the oxide film increased, so it was more difficult to be removed by acid pickling.     

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At present question on quality of duplex stainless steel 2205 increasingly focuses on the surface defects. The morphology, chemical composition and microstructure of the peeling defects on the surface of hot rolled plate of duplex stainless steel 2205 were investigated using stereo microscope, OM and SEM. The results show that the peeling defects on the surface of hot rolled plate are of wavy structure?? one end of it connects to the steel matrix and the other one cracks on the surface of hot rolled plate. There are inclusions of Al2O3 and CaO- SiO2- Al2O3- MgO distributed in shapes of point and chain and the volume fraction of the austenite is very high (58. 5%) at the defects. This causes low plasticity at the defects, which is the main reason for the peeling defects to appear in the region. Based on the results of the analysis, a phenomenological model for describing the formation of peeling defects was established.     

Effects of Ca and B on the Strip Deformation of Cold Rolled Duplex Stainless Steel Type 2205 during Continuous Annealing

The effects of Ca and B on the strip deformation of duplex stainless steel Type 2205 under continuous annealing conditions were investigated. For the creep test, the stresses were calculated from the line tension applied to hot rolled and cold rolled Type 2205 strip during continuous annealing. It was found that the cold rolled Type 2205 steel showed more prominent superplasticity as compared with the hot rolled steel, which could be attributed to the fine grain size of the cold rolled steel. The creep rate of cold rolled Type 2205 steel decreased with the Ca and B additions due to the grain boundary segregation of B. It is suggested that the rate controlling mechanism for the strip deformation of cold rolled Type 2205 steel seems to be grain boundary diffusion in γ phase.     

The Development of Hot Rolled Automobile Beam Steel Plates 500L-Z With Excellent Surface Oxide Layer

This paper has determined the compositions and hot rolling processes of the hot rolled beam steel plates with excellent surface oxide layer for automobiles by investigating the oxide layer forming principle and its influence factors,and the feature of the steel oxide layer.The microstructure,mechanical properties,oxide layer shape and structural composition of the steel plates are analyzed by using metallographic structures examination,SEM analyzing,X-ray diffraction instrument and mechanical properties testing.The result shows that the trial hot rolled frame steel plates have an excellent oxide layer adhesion,the Fe 3 O 4 proportions is greater than 85% in the oxide layer,and the oxide layer thickness is less than or equal to 10μm.The product has been trial-manufactured more than 100 thousands ton,and used to stamp the beam parts of automobiles straightly in no pickling process.The oxide layer scarcely scales off from the steel plates,and the effect is remarkable.     

卷取后的热轧带钢氧化铁皮显微分析

氧化铁皮的显微结构是决定热轧带钢酸洗性能的本质因素之一。应用SEM、EDS、EBSD技术,分析研究了卷取后的热轧带钢氧化铁皮显微结构特征,结果表明在卷取后的不同取样条件下,钢卷相同位置的氧化铁皮厚度基本不变,而表面和截面显微形貌、相组成、晶粒度则存在明显差异。     

卷取后的热轧带钢氧化铁皮显微分析

氧化铁皮的显微结构是决定热轧带钢酸洗性能的本质因素之一。应用SEM、EDS、EBSD技术,分析研究了卷取后的热轧带钢氧化铁皮显微结构特征,结果表明在卷取后的不同取样条件下,钢卷相同位置的氧化铁皮厚度基本不变,而表面和截面显微形貌、相组成、晶粒度则存在明显差异。     

Pickling of Process‐Oxidised Austenitic Stainless Steels in HNO3‐HF Mixed Acid

Oxide formation during production annealing and the subsequent pickling response in mixed acid have been studied. The aims were to characterise the oxides formed and to understand how the pickling mechanism and kinetics are affected by the nature of the oxide. Totally, eight different versions of the austenitic stainless steel grades AISI 301, 304L and 309L were studied, all annealed in production lines. Cold rolled oxides (formed during annealing) are thin (< 1 µm), dense and formed in a multilayered manner. Hot rolled oxides (formed during reheating, hot rolling and annealing) are thicker (>1 µm) and more heterogeneous in thickness and composition. The dissolution rate of the chromium depleted layer (CDL) under the oxide is the most important factor for the overall pickling rate. The permeability of acid through the oxide and the tendency of the oxide to spall are also important factors affecting the pickling kinetics. The dense oxide formed on cold rolled materials can to some extent hinder the acid to reach the CDL. The oxides on hot rolled materials are porous and do not provide such a barrier but they are thicker and thereby more difficult to remove. Shot‐blasting prior to pickling of the hot rolled materials improves the pickling performance because it thins the oxide, improves the permeability and increases the tendency of the oxide to spall during the pickling step.     

304奥氏体不锈钢带氧化铁皮直接冷轧技术的研究

结合现场生产实际,通过在试验室对奥氏体不锈钢304黑皮卷直接进行压下率分别为10%,20%,30%的冷轧然后退火酸洗的试验,证明在退火酸洗工艺相同的情况下,通过在热轧后进行一定压下率的直接轧制,可以获得与传统No.1产品相比晶粒尺寸等级相同、表面粗糙度更低、力学性能和耐蚀性相近的2E产品,并且获得更大的热轧产品厚度范围,降低冷轧一个轧程后的产品厚度.因此根据不同客户的要求,可以用2E产品替代No.1产品.     

不锈钢/碳钢耐蚀海水带肋钢筋轧制复合工艺

摘要：海洋工程用带肋钢筋要求有耐氯离子腐蚀能力，但选用双相不锈钢生产成本过高，不锈钢 碳钢轧制复合钢筋则可兼顾耐蚀性和低成本。覆层采用2205不锈钢，基材为低合金钢20MnSi，用有限元方法模拟钢筋的热轧复合过程，分析轧制过程尤其是成品孔中轧件的变形规律。有限元仿真发现，矩形组合坯料无孔型轧制时，其角部复合困难，而成品孔轧制时，钢筋横肋根部的应变最大，覆层在此位置减薄显著，应选择合适的复合坯覆层厚度。在实验室采用焊接、真空处理和热轧方法制备了直径为16mm的复合钢筋，屈服强度为485MPa，抗拉强度为701MPa，断后伸长率约为37.1%，复合界面剪切强度为317.5MPa。复合钢筋呈良好的冶金结合，Fe和Cr的扩散层厚度约为40μm。该工艺生产的复合带肋钢筋成本较不锈钢降低50%以上。