中厚板轧材探伤不合的原理分析与措施

因铸坯内部质量原因造成轧材探伤不合的原因主要有四个,分别是氢致裂纹,铸坯内部的中心偏析与裂纹,铸坯内部的夹杂物和铸坯内部的带状组织发达。本文针对中厚板生产中出现的轧材分层问题展开分析,从连铸坯的内部质量缺陷和轧钢的压下量等方面分析轧材分层产生的原因及预防措施。     

Q345B宽带钢边缘裂纹分析

采用化学成分分析、力学性能测试、显微组织观察和夹杂物检验等方法对有边缘裂纹的Q345B宽带钢进行分析。发现是由于铸坯存在FeS,MnS等夹杂物,轧制中这些夹杂物及过高锰含量导致裂纹的进一步扩展,最终形成边缘裂纹。     

Q345B中厚板表面的纵裂纹分析

采用金相检验和扫描电镜及能谱分析等手段对热轧Q345B中厚板表面纵裂纹进行了分析.结果表明,热轧Q345B中厚板表面纵裂纹是由于铸坯中存在夹杂物及铸坯纵裂引起的.通过对炼钢生产过程的观察,提出了改进连铸工艺等相关措施,取得了良好的效果.     

CSP热轧钢板伸长率异常偏低原因探析

对在日常检验过程中出现的两个伸长率异常偏低的试样进行了理化检验和分析,并与一个合格试样进行了比较。结果表明：由于连铸铸坯内存在大量非金属夹杂物,导致基体与夹杂物之间产生内应力,因此在拉伸过程中促使裂纹的迅速扩展,形成穿晶裂纹和空洞,最终呈现伸长率偏低的结果。     

大样电解法分析连铸板坯大颗粒非金属夹杂物来源

采用大样电解方法萃取Q235B钢连铸板坯中的大颗粒非金属夹杂物,用扫描电镜及能谱对比分析了连铸坯内弧、外弧、中心部位的夹杂物成分,判断了非金属夹杂物的来源,结果可为进一步提高连铸板坯的纯净度提供借鉴。     

06Cr19Ni10不锈钢中大型夹杂物的分析

通过对06Cr19Ni10不锈钢连铸坯中存在的大型夹杂物的形貌和化学成分进行分析,找出了大型夹杂物的形成原因,并给出了防止该类大型夹杂物产生应采取的措施。结果表明：06Cr19Ni10不锈钢中的大型夹杂物属于以CaO-SiO2-Al2O3-MgO为主要成分的脆性夹杂物;初步分析认为该大型夹杂物是在冶炼过程中没有上浮的炉渣在连铸时裹入钢液中形成的,也有可能是沉积在结晶器上的氧化物被下泄的钢液冲入结晶器中进而进入连铸坯所致。     

汽车大梁用热轧卷板冶炼研究与应用

本文主要论述了汽车大梁用热轧卷板的冶炼生产工艺。转炉冶炼的重点是终点成分控制,精炼操作的重点是增碳及脱氧。采用合理的脱氧合金化制度和良好的保护浇注措施,稳定控制中间包钢水温度、拉速、冷却水量可以获得较低的夹杂物含量、良好的铸坯内部质量。     

Q460C中厚钢板折弯裂纹形成原因

某厂生产厚度为20 mm的Q460C钢板在折弯过程中出现裂纹。采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析等方法分析裂纹产生的原因。结果表明：试样折弯裂纹产生的主要原因为炼钢过程中钢液中P、S元素含量过高,且连铸过程存在钢包下渣的情况,导致铸坯中产生P、S元素偏析,铸坯内部存在大量非金属夹杂物;随着轧制过程温度的不断降低,钢板内部形成严重的带状组织,最终导致钢板在折弯过程中发生开裂。     

圆钢纵裂分析

针对进口的45铜在连铸坯轧制大规格圆铜(≥Ф160mm)时产生的纵向裂纹．借助扫描电镜，从裂纹形态等方面进行了观察和分析。结果表明，圆钢的裂纹内部有夹杂物，两侧有脱碳现象，裂纹末端沿铁素体偏析带延伸．偏析带内部也存在夹杂物，由此证实，原材料中存在的成分偏析带以及偏析带内的夹杂物是导致轧制后圆钢纵裂的根本原因，     

Ti对Fe-Ni膨胀合金凝固组织的影响

采用变质处理法和扫描电镜(SEM)研究了Ti对Fe-Ni膨胀合金凝固组织的影响.结果表明:经Ti变质处理后,Fe-Ni膨胀合金中形成了大量的Ti2O3-MnS高熔点复合夹杂物,尺寸约为2μm;Ti2O3复合夹杂物在凝固过程中作为非自发形核核心,使铸坯凝固组织细化.Ti在凝固组织的等轴晶和柱状晶晶界上以TiN,TiC,Ti(NC),Ti2O3形式存在,在一定程度上起到阻止晶粒长大的作用.     

Prediction of spatial distribution of the composition of inclusions on the entire cross section of a linepipe steel continuous casting slab

In the current study, the transformation in the composition of non-metallic inclusions from the molten steel to the solidified steel was studied and the composition distribution of inclusions on the cross section of a linepine continuous casting slab was predicted. During cooling and solidification of the continuous casting strand, Al₂O₃-CaO inclusions reacted with the bulk steel and transformed to CaS-Al₂O₃-MgO-(CaO) ones in the continuous casting slab. The composition of inclusions on the cross section of the slab varied with locations due to the varied cooling rate. A model was established to predict the distribution of the composition of inclusions on the cross section of the continuous casting slab, coupling solidification and heat transfer of the continuous casting slab, the kinetic mass transfer of the dissolved elements in the solid steel, and thermodynamic calculation of inclusion transformation at different temperatures. The composition transformation of inclusions mainly occurred at the temperature between the liquidus and solidus of the linepipe steel. Inclusions were mainly CaS-Al₂O₃-MgO-(CaO) in slab center and were MgO-Al₂O₃-CaO-CaS within the subsurface of the slab. In the slab, the transformation fraction of inclusions was less than 10 % at corners while it reached 70 % at 50 mm below the surface of the slab.     

ARI-3460型光电直读光谱仪测定轴承钢连铸坯中低钛

本文介绍了利用ARL-3460型光电直读光谱仪测定轴承钢连铸坯中低的钛。由于公司冶炼的部分轴承钢连铸坯中的钛含量要求不大于30ppm,所以我们采用了含量分段检测,分析结果准确可靠,满足了生产需要。     

Variations in steel cleanness during transient continuous casting practices

Abstract

During sequenced continuous casting, concerns have been expressed about the density of nonmetallic inclusions present in steel slab produced during the transition period as successive ladles are teemed. Consequently, for critical applications such as thin wall tinplate products, with can wall thicknesses of ～0.26 mm, only steel cast during 'steady state' conditions is selected. In contrast, slab cast over defined lengths before and after a ladle change is downgraded to less demanding applications, irrespective of cleanness. To evaluate this practice, steel inclusion levels have been assessed during ladle change operations, when the steel reservoir in the tundish fell to below 20 t. This plant based study confirmed that, during the transition period, marked variations occur in the size and morphology of the nonmetallic inclusions, as well as in the oxygen content of the steel slab.     

取向硅钢制备工艺及其发展趋势

取向硅钢作为一种重要的铁芯材料,在电力行业中有着广泛的应用.基于生产工艺及技术特点,取向硅钢的制备工艺可以分为传统厚板坯工艺、薄板坯连铸连轧工艺及双辊薄带连铸工艺.传统的厚板坯工艺是工业生产取向硅钢的主要方法,其按加热温度又可分为板坯高温加热、板坯中温加热以及板坯低温加热工艺,其中板坯低温加热工艺具有加热温度低、能耗少...     

薄板坯连铸连轧生产石油套管用J55钢板的实践

结合本钢FTSR薄板坯连铸连轧生产线设备和工艺,开发了薄板坯连铸连轧石油套管专用J55钢。分析了薄板坯连铸连轧工艺与材料组织性能的特点,设计了舍金成分、炼钢工艺和轧钢工艺,进行了现场试生产,检验了产品微观组织和性能。在C—Mn基础上加Nb、Ti微合金化,采用LF＋RH的炉外精炼工艺,结合合理的控轧控冷工艺,达到净化钢质、改善夹杂物形态及分布,提高钢材综合力学性能的目的。     

Breakout of a slab as the result of changes in the thermophysical properties of continuously cast steel

The so‐called secondary cooling zone is an important part of the continuous casting machine. In this zone, a breakout may occur because of an increase of the local and temperature heterogeneity of steel, resulting from an increase of the stress caused by bending of the slab and by high local concentration of nonmetallic slag inclusions. Changes of the chemical composition of steel during continuous casting are particularly dangerous. In the event that two melts are cast one after another, that is, if the melt of steel with chemical composition A ends and is immediately followed by the steel B, it may automatically stop the continuous casting machine, and an atypical breakout may take place. It has happened during continuous casting of the slab, 250 × 1530 mm in the area of straightening, 20 min after flying change of tundish. In the present paper, by employing the dimensional analysis, eight dimensionless numbers are derived. If the values of these dimensionless numbers for two followed steels significantly differ, the atypical breakout may take place.     

不锈钢／普碳钢复合连铸技术及模拟研究

利用长、短水口结合电磁制动技术在同一结晶器内连铸复合钢坯是刚刚发展的一项新工艺。本文发展一种数学模型分析该工艺过程结晶器内两种异质钢液流动及分布特征。采用低Reynolds数湍流模型计算湍流参数，并以虚拟凝固壳来代替实际的凝固计算。通过与文献中的实验结果对比和较系统的数值分析，证明了模型的可靠性和所提方法改善工艺的作用。     

钢板表面纵向裂纹的金相检验和分析

在连铸轧制的钢板表面有沿轧制方向的裂纹。采用化学成分分析，宏、微观检验等方法对裂纹进行了分析。结果表明，裂纹中存在氧化物及其脱碳等缺陷，这说明连铸坯表面在轧制前已存在裂纹并在轧前加热中裂纹内发生氧化和脱碳，导致轧制后的钢板表面出现裂纹。     

Q235B钢热轧板带孔洞及边裂缺陷成因分析

采用宏观分析、化学成分分析、金相检验以及能谱分析等方法,对某钢铁公司生产的Q235B钢热轧板带中部孔洞和边裂缺陷的成因进行了分析。结果表明：该类热轧钢板的中部孔洞和边裂缺陷是由于连铸工艺出现异常,造成连铸板坯边部产生表层气孔以及中部产生较严重的硫偏析,从而使钢板中部生成了大量的条带状硫化物,特别是低熔点FeS的生成导致了中部孔洞缺陷的产生;而连铸板坯边部的表层气孔在轧制过程中导致了边裂缺陷的产生。     

连铸轴承钢质量的研究

采用宏观与显微分析方法对轴承钢连铸坯进行了剖析，揭示了连铸坯的氧、碳含量及各类夹杂的分布规律。结果表明，铸坯能满足高、低倍质量要求，中间包高液位和低温浇注有利于减少边缘夹杂。