连退板浅表层的富集元素表征

为了研究连退板表层元素富集行为及相互作用,借助扫描电镜、辉光放电光谱仪、光电子能谱仪和透射电镜等技术手段对铝镇静钢和双相钢连退板表层中的富集元素进行了详细地表征与分析。结果表明,铝镇静钢连退板表面的主要富集元素有O、Mn和Al;而双相钢连退板表面的主要富集元素有O、Mn和Si。沿着浅表层深度分析可知,对于合金元素含量较高的双相钢,沿浅表层富集更深,富集深度约为50 nm;而合金元素含量较低的铝镇静钢,富集深度仅约为25 nm。综合分析不难发现,相对于铝镇静钢,双相钢添加了Si元素以后在其表面优先富集Si元素并同时形成了Si的氧化物,从而导致Al元素的富集及氧化物的形成受到了抑制。     

钢中铝对铝镇静钢浸锌性的影响

1)绪言:众所周知,钢中 Al,Si、Mn、Cr 等易氧化元素,由于在氢气中加热而富集于钢板表面,从而降低了镀锌板质量及其制造特性。本文就铝镇静钢中铝在钢板表面的富集及其浸锌性的关系进行了闸述。     

双相钢中铝含量对表面氧化物及抑制层形貌的影响

 对3种不同铝含量的热镀锌双相钢进行连续退火镀锌模拟试验。研究表明：wAl=009%的双相钢表面的氧化物形貌为颗粒状和长条状的氧化物;XPS分析表明,这两种氧化物为MnO和Cr2O3。含铝wAl=012%的双相钢表面均匀分布扁平状的氧化物,氧化物平均直径为1262nm。含铝wAl=04%的双相钢表面为细小弥散分布的氧化物,平均直径为707nm。除了MnO和Cr2O3,这两种双相钢表面还生成了Al2O3。Fe-Al抑制层晶粒之间的空隙程度随着铝含量的增加逐渐变大,抑制层的致密度下降,其中含铝wAl=04%的双相钢表面的抑制层晶粒粗大。从表面氧化物与锌液有效铝之间反应的角度出发解释了抑制层形貌的变化。     

镇静钢表面富集状况对镀锡板耐蚀性的影响

一、前言近年来采用连铸钢作镀锡板的基本材料有很大的增加。然而,连铸钢和沸腾钢的铸锭相比较含有较高的 Si 和 Al。许多试验证明,钢中这些元素在箱式退火中趋向于富集在钢的表面。本研究旨在探讨镇静钢薄板表面富集的 Si、Al 和 Mn 对镀锡板耐蚀性的影响。     

780 MPa级双相钢条状色差缺陷成因及改善措施

 针对780 MPa级双相钢表面存在严重的条状色差缺陷,从微观特征方面进行系统研究。采用SEM及EPMA分析手段研究缺陷表面情况,结果表明,缺陷处微观形貌呈粗糙破碎状,破碎的密集程度和缺陷的严重程度正相关;能谱和电子探针证明,破碎处只存在轻微氧化。应用辉光手段分析表层富集情况,色差严重程度与硅、锰等元素富集峰值距表层深度密切相关,结合热轧截面分析富集现象在热轧以橄榄石相的形式存在,宏观表现为条状红铁皮,该铁皮经过酸洗后难以除尽,在后续冷轧时不同区域表层元素富集深度及破碎密集程度存在差异,表现为连退板表面的条状色差缺陷。在此研究基础上优化热轧和冷轧生产控制方案,最终有效降低或消除了连退板表面条状色差缺陷。     

露点对预氧化还原QP钢表面选择性氧化的影响

以0.2％C-1.8％Si-1.8％Mn成分的QP钢为研究对象,采用预氧化还原模拟试验,在露点分别为-40℃和+10℃的N2-5％(体积分数)H2气氛中制备了预氧化还原试样,使用GD-OES分析了表层5 μm深度范围Fe、Si、Mn、O的元素深度分布,使用SEM观察了表面形貌,使用TEM观察了 FIB制备的截面试样微观形貌.结果表明:预氧化试样表面氧化铁/基板界面位置已存在Si、Mn富集,经过还原退火后,还原铁/基板界面位置的Si、Mn富集进一步增加.提高退火气氛露点促进了 Si、Mn在钢板次表层形成内氧化;减少了还原铁/基板界面位置的Si、Mn外氧化;改变了还原铁/基板界面位置的氧化物组成和结构,由Si-O和Mn-Si-O的双层结构变为Mn-Si-Fe-O复合氧化物结构.     

表面氧化物对高强度冷轧钢板磷化处理性能的影响

Si和Mn是钢材的基本合金元素,这些合金元素不仅对氧化敏感,容易在钢材表面形成氧化物,而且对钢板的表面性能如磷化处理性能也有很大的影响.另一方面,近年来为提高汽车防碰撞性能和减轻车身重量,对汽车用冷轧钢板强度的要求越来越高.为提高钢板的强度,添加这些合金元素是非常有效的办法.为调查Si和Mn对磷化处理性能的影响,从表面氧化物的观点出发,分析了添加Si和Mn后钢板表面形成的氧化物的种类和分布形态.结果发现,添加Si后钢板的磷化处理性能变差,这是因为钢板表面形成的Si氧化膜会破坏磷化处理性能.同时还发现氧化物的形成除受Si含量的影响外,还受Mn含量的影响,即使在Si含量较高的情况下,控制Mn含量也可以提高钢板的磷化处理性能.     

一种600MPa级冷轧双相钢的生产方法

<正>专利号:201210200751.9专利权人:河北钢铁股份有限公司邯郸分公司本发明不添加任何合金元素,改良了C-Si-Mn系列双相钢的成分,降低了Si含量,增加了Al含量,通过改进炼钢、热轧工艺、冷轧连退工艺,生产出屈强比低、延伸率高的冷轧双相钢;成本低,生产连续性较好,产品质量稳定。本发明成品力学性能指标:屈服强度360~430 MPa,抗拉强度≥600 MPa,延伸率≥     

退火过程IF钢表面氧化膜形成及其电化学性能研究

IF钢具有低屈强比、高伸长率、良好的深冲性能和无时效性等优异性能,被广泛应用于汽车等制造产业中。研究表明,IF钢表面形成的氧化膜对其耐蚀性具有重要的作用。采用XPS、EBSD、XRD和电化学分析方法,研究了退火过程IF钢表面氧化膜形成及其电化学性能。结果表明,在退火过程中不同合金成分IF钢晶体织构发生显著变化,且合金成分Si和Mn元素存在着明显的迁移行为。对于高Mn含量的IF钢表面氧化膜富集了锰氧化物和硅氧化物,降低了氧化膜的致密性,进而降低了氧化膜的自腐蚀电位和电阻值,提高了的自腐蚀电流,导致其氧化膜耐蚀性能下降。     

硅铝钡铁合金用于转炉炼钢脱氧与合金化

硅铝钡铁合金是新研制的一种节铝型复合脱氧剂。在120t转炉上,对镇静钢的十几个钢种进行用硅铝钡铁合金脱氧合金化的试验研究,结果表明:在硅铝钡铁合金(Si20％,Al40％,Ba7～8％)的加入量与硅铝铁合金(Si20％,Al50％)的加入量基本相同的条件下,钢中酸溶铝含量基本不变,可平均节铝约22％。同时,钢中氧化物夹杂含量平均减少29％,钢中非金属夹杂物形态有所改善,钢材的力学性能也有所提高,经济效益显著。     

Effect of the presence of alloying elements in interstitial-free and low-carbon steels on their surface composition after annealing in reducing atmospheres (dew point=−30 °C)

The X-ray photoelectron spectroscopy (XPS) method is used to study the outer surfaces of interstitial-free (IF) and low-carbon (LC) steels with different alloying element contents (P, Ti, Nb, and Mn) after annealing at temperatures of 805 °C and 705 °C, respectively, for 40 seconds in reducing atmospheres (dew point=−30 °C). The work discussed seeks to establish possible relationships between the bulk composition of the IF and LC steels and the contents of segregated alloying element observed by XPS on the surface of the annealed steels, as well as to establish the influence of the presence of a thin iron oxide film on the steel surface on the segregation and oxidation of the alloying elements. Despite the low Mn and Si bulk steel contents and the shortness of the annealing cycle, considerable enrichment of these elements on the surface is seen, mainly as manganese and silicon oxides. The formation of a MnO layer on the annealed steel surface seems to be related to the reduction of iron oxides and the increase in the metallic Fe content. Despite its low content in LC steels, carbon also seems to diffuse towards the annealed steel surface to reduce iron oxides.     

The Development of a Processing Window for the Continuous Galvanizing of a Mn–Cr–Si Martensitic Steel

Martensitic or complex phase steels are leading candidates for automotive impact management applications. However, achieving high strengths while obtaining high quality coatings via continuous galvanizing is a challenge due to cooling rate limitations of the processing equipment and selective oxidation of alloying elements such as Cr, Mn, and Si adversely affecting reactive wetting. The galvanizability of a Cr? Mn? Si steel with a target tensile strength above 1250 MPa was investigated within the context of the continuous galvanizing line. The continuous cooling transformation behavior of the candidate alloy was determined, from which intercritical and austenitic annealing thermal cycles were developed. The evolution of substrate surface chemistry and oxide morphology during these treatments and their subsequent effect on reactive wetting during galvanizing were characterized. The target strength of 1250 MPa was achieved and high quality coatings produced using both intercritical (75% γ) and austenitic (100% γ) annealing using a conventional 95%N₂–5%H₂, ?30°C dew point process atmosphere and 0.20 wt% dissolved (effective) Al bath, despite the presence of significant Mn and Cr oxides on the substrate surfaces. It is proposed that complete reactive wetting by the Zn(Al, Fe) bath was promoted by in situ aluminothermic reduction of the Mn and Cr‐oxides by the dissolved bath Al.     

Hot-dip galvanising behaviours of a CMnSiCr DP780 steel

In order to evaluate the galvanisability of a CMnSiCr DP780 steel, which is originally designed for manufacturing continuously annealed bare steel sheet, hot-dip galvanising experiments were conducted on a hot-dip process simulator. The process and galvanising behaviours were investigated. The results indicate that the alloying elements such as Si, Mn and Cr segregate and selectively oxidise at the surface during annealing. Besides external oxidation, internal oxidation of Cr and Mn is observed. Aluminothermic reducing reaction is effective to reduce the negative effect of surface oxides on the galvanisability of this steel and improve the coating quality. According to the measurement results and discussions, it is believed that this CMnSiCr DP780 steel could possibly be used to produce the corresponding hot-dip galvanised or galvannealed product when further increasing the Al content in Zn bath slightly, especially for galvannealed product.     

加热工艺对含磷高强钢氧化行为的影响

 含磷高强钢具有良好的成形性能和较高的强度,被广泛用于汽车零件冲压成形。除了磷元素,含磷高强钢中通常还含有锰、硅等合金元素进行固溶强化,这些合金元素在退火过程中容易发生选择性氧化。采用镀锌模拟器研究了加热过程的露点温度对含磷高强钢在加热过程中的氧化行为。采用扫描电镜、辉光放电光谱仪以及光电子能谱仪分别分析了含磷高强钢的表面微观形貌、元素深度分布以及表面化合物种类。结果表明,加热过程的露点温度对合金元素在表面的氧化行为有显著影响,较高的加热过程露点温度可以显著抑制锰元素和硅元素在表面的选择性氧化行为,但是会加速磷元素在表面的偏析。进一步研究表明,磷元素在样品表面以磷酸盐形式存在。     

Galvanizing and Galvannealing Behavior of CMnSiCr Dual-Phase Steels

Alloying elements, such as Mn, Mo, Si, and Cr, are commonly used to enhance the strength of advanced high-strength steels. Those elements also play an important role in the hot-dip galvanizing (GI) and galvannealing (GA) process. In this study, two kinds of CMnSiCr dual-phase steels were galvanized and galvannealed using a hot-dip simulator to investigate the effect of the alloying elements on the microstructure of the GI and GA coatings. The results showed that the dual-phase steels had good galvanizability because no bare spots were observed and the Fe-Zn phases were readily formed at the interface. However, the alloying reaction during the GA process was significantly hindered. XPS analysis showed that external oxidation occurred under an extremely low dew point [213 K to 203 K (?60 °C to ?70 °C)] atmosphere during the annealing prior to hot dipping. However, most of the oxides were reduced during the GI process. After the GI process, the Al was present as solid solutes in the Fe-Zn phase, suggesting that the Fe-Zn phase was formed from the transformation of the Fe-Al inhibition alloy. Meanwhile, the solubility of Si in the ζ phase was extremely low. With continued GA reaction, the ζ phase transformed into the δ phase, which contained approximately 1.0 at.pct Si. The Si also diffused into the Zn layer during the GA reaction. Hence, the ζ phase did not homogeneously nucleate at the steel substrate/Zn coating interface, but was found at the area away from the interface. Therefore, the Fe-Zn phases on the CMnSiCr dual-phase steels were relatively non-uniform compared to those on interstitial-free steel.     

过时效工艺对C-Mn-Si高强钢表面选择性氧化的影响

 为了研究过时效过程露点调节技术在高强钢上的应用，采用热浸镀工艺模拟器研究了过时效工艺中气氛露点温度（－30、－10 ℃）和温度（250、350 ℃）对一种C-Mn-Si高强钢选择性氧化的影响，分别采用FE-SEM和EDS观察分析了试样表面形貌和化学成分，采用GDOES表征了试样表面的元素深度分布，采用XPS确定了氧化物种类。结果表明，高过时效温度（350 ℃）和高露点温度（－10 ℃），可显著抑制锰和硅在钢表面的选择性氧化，此时试样表面为无定型SiOx、无定型MnOx以及纯态锰。随着过时效温度和露点温度的降低，锰和硅在表面的富集明显增加，同时发现，露点温度对合金表面元素富集峰值的影响比过时效温度更显著。采用低过时效温度（250 ℃）和低露点温度（－30 ℃）时，试样表面出现大量富锰和硅的颗粒状氧化物，由晶态的Mn3O4和MnO2以及硅的非化学计量氧化物SiO1.49和SiO0.93组成。     

快冷工艺对冷轧双相钢组织性能的影响

以C-Si-Mn系相变强化冷轧高强度钢板为研究对象,研究了连续退火快速冷却工艺对冷轧双相钢组织和力学性能的影响。研究发现,对于双相钢,在连退冷却能力不足的情况下,需添加合金元素,使CCT曲线右移,降低双相钢的临界冷却速率;在提高连退快冷冷却速率的情况下,可以减少合金元素的添加量,节约成本。冷却速率越高,双相钢的强度越高,延性下降。     

合金元素对焊丝钢氧化皮结构及剥离性的影响

利用金相、扫描电镜观察及电子探针(EPMA)面分析技术等研究了合金元素(Si、Mn、Ni、Cr)对焊丝钢盘条氧化皮显微结构的影响,并采用拉伸试验及酸洗试验评价氧化皮的剥离性。结果表明,Si、Ni和Cr元素对氧化皮显微结构的影响大于Mn元素;低碳钢的氧化皮主要为Fe的氧化物,其最内层和中间层的氧化物均以柱状晶形式垂直基体向外生长;在低碳钢基础上增加Si含量,可显著降低氧化皮总厚度,氧化皮最内层为富Si层,且氧化皮/基体界面的凹凸度增加;进一步增加Ni含量,最内层的合金富集层以锚状沿晶界向基体内延伸。降低氧化皮/基体界面凹凸度、减少合金富集层均利于氧化皮剥离,机械法对界面凹凸度更敏感,而酸洗法对氧化皮缺陷数量较敏感。