薄板坯连铸连轧流程试制取向硅钢抑制剂的析出特点

 在实验室模拟薄板坯连铸连轧流程试制取向硅钢的基础上,通过大量的透射电镜观察和分析检测,得到了脱碳退火后钢中形成的析出物的情况,确定了钢中的主抑制剂为Cu2S,同时还存在少量的辅助抑制剂AlN以及以复合析出物形式存在的微量的MnS。研究了Cu2S主抑制剂在薄板坯连铸连轧流程生产取向硅钢的析出特点,分析了实验用钢中Cu2S抑制力。结果表明,Cu2S作为薄板坯连铸连轧流程生产普通取向硅钢的主抑制剂有足够的抑制能力,能够满足CGO钢二次再结晶的要求。     

低温高磁感取向硅钢连铸与均热过程AlN与MnS析出的热力学

针对薄板坯连铸连轧流程结合"获得抑制剂法"所制备的低温高磁感取向硅钢,通过热力学计算研究了AlN与MnS在连铸与均热过程中的析出规律与行为。计算结果表明,连铸过程中AlN在凝固后的高温α相中便可能析出,而MnS仅可能在凝固后的α+γ两相区内析出。钢中AlN与MnS在均热过程中均处于部分固溶与部分析出的状态。后续高温渗氮处理后初次晶粒的异常长大并不明显,表明渗氮处理前钢中固有抑制剂的数量相对充足。     

薄板坯连铸连轧取向硅钢流程中Cu_2S抑制剂的析出行为

研究了Cu2S抑制剂在薄板坯连铸连轧流程生产取向硅钢全流程中的析出特点。结果表明:典型成分取向硅钢主抑制剂Cu2S在全工序进程中析出粒子呈不断长大的趋势,粒子分布密度与体积分数在高温退火前也不断增加,高温退火净化后,剩余粒子变大,分布密度大大降低,对应体积分数也降低。     

3%取向硅钢中MnS沉淀析出动力学的计算

利用第二相相关理论计算分析薄板坯连铸连轧3%取向硅钢中MnS沉淀析出的动力学行为。沉淀析出计算结果显示在薄板坯连铸连轧生产工艺中以铁素体位错线上形核为主导,MnS在铁素体中的析出量最大,其有效沉淀温度范围约为700~900℃,临界形核尺寸约为0.7~1.5 nm;相变完成时MnS颗粒的半径约为30 nm,可以起到抑制剂的作用。终轧温度应在800℃以上。     

普通取向硅钢的热塑性研究

对实验室模拟薄板坯连铸连轧流程试制成功的普通取向硅钢的铸坯进行高温力学性能测试,分析动态再结晶、析出物和相变对取向硅钢热塑性的影响。结果表明:试验取向硅钢无第Ⅱ脆性区;第Ⅲ脆性区的温度范围约为850~600℃;晶界析出物和相变是第Ⅲ脆性区取向硅钢塑性变差的主要原因。     

低温加热生产取向硅钢中MnS和Cu_2S的竞相析出

针对薄板坯连铸连轧流程(TSCR)生产具有低温加热(1200℃)抑制剂成分取向硅钢,研究了薄板坯连铸、均热以及热连轧过程中MnS和Cu2S的析出特征,研究结果表明,连铸过程形成的MnS在1180℃下难以完全固溶,并形成尺寸为200~600 nm的粗大MnS粒子,而在此温度下Cu2S可以完全固溶并在热连轧过程中细小弥散析出,平均粒子尺寸约为30 nm,可以作为取向硅钢的有效抑制剂。     

薄板坯连铸连轧流程生产取向硅钢技术分析

 介绍了国内外取向硅钢生产现状与流程技术发展趋势。从流程工序特点、热履历、抑制剂类型等方面进行对比,分析了薄板坯连铸连轧和传统板坯流程之间存在的差异性。在总结薄板坯连铸连轧生产取向硅钢技术优势的基础上,提出了该流程研究需要解决的技术难点。     

硼对低碳铝镇静钢中AlN、MnS析出的影响

通过实验室模拟薄板坯连铸连轧(TSCR)流程实验,研究了向低碳铝镇静钢中加入质量分数为3.0×10-3%的微合金元素B对AlN、MnS在连铸连轧过程中析出的影响.结果表明:微合金元素B可以在高温奥氏体中优先与自由N结合形成粗大BN颗粒,且常与MnS复合析出,抑制了细小AlN的析出,减少了钢中细小AlN的含量.     

CSP工艺钛微合金碳钢中的碳氮化钛析出相

 应用透射电镜、高分辨电镜等方法观察分析了薄板坯连铸连轧EAF-CSP工艺生产的微钛低碳钢热轧板的含钛析出相,实验钢的成分为(mass%）：C：0.04~0.07%、Si：0.6%、Mn：0.6%、Ti：0.06~0.14 %。电解萃取及X射线衍射分析结果表明：钢中存在不同碳氮比的碳氮化钛析出相,这些碳氮化物的C/N比值的差异是由各个析出相的形成温度及析出时钛和氮、碳元素在钢中的过饱和度不同而造成的。实验钢萃取粉末（包括各种析出相）的质量分数约占钢的0.305%。其中五分之四左右为渗碳体,另外五分之一主要是钛的碳化物、氮化物和碳氮化物,还有少量的硫化物和氧化物。 在薄板坯连铸连轧工艺的连铸坯及热轧板中均观察到了由相间沉淀方式形成的碳氮化物粒子列。本文讨论了相间沉淀的形成机制。与传统连铸连轧工艺生产的同类钢相比,CSP工艺低碳钢中微量钛的加入明显增加了细小析出相的数量。     

2种流程生产的中高碳钢的差异及产生原因

针对传统流程和薄板坯连铸连轧2种流程生产的中高碳钢的差异进行了对比分析并探究其产生的原因.研究结果表明:与传统流程相比,薄板坯连铸连轧铸坯的冷却速度和凝固速度快,钢中易偏析元素来不及扩散偏聚,非金属夹杂物也不易聚集长大,碳的最大偏析度为1.16,较传统流程有明显改善,氧化物、氮化物、硫化物等非金属夹杂物的尺寸较细小但数量明显多于传统流程.同时,由于薄板坯连铸连轧流程具有铸坯加热温度低、在炉时间短的特点,有利于降低铸坯表面碳的扩散速度,减少脱碳量,脱碳层深度小于板带厚度的1.0％,为传统流程脱碳层深度的30％～60％.     

取向硅钢中含铜抑制剂的固溶析出行为

含铜抑制剂作为取向硅钢的主抑制剂或辅助抑制剂不仅可以抑制初次晶粒的长大,促进二次再结晶,还可以降低铸坯的加热温度。取向硅钢中主要抑制剂为10～50 nm Cu₂S,在钢的铸坯、热轧、冷轧、脱碳等工艺过程均可析出;(Cu,Mn)_1.8S、Cu_1.8S、ε-Cu等主要作为辅助抑制剂,尺寸一般为30～50 nm(或大于50 nm),主要在热轧阶段析出。总结了国内外有关取向硅钢中含铜抑制剂析出行为的研究进展,当前主要研究不同生产流程和工序中含铜抑制剂的析出行为和作用机理。     

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The precipitation behavior of MnS and AlN in low-temperature high magnetic induction grain-oriented silicon steel produced by thin slab casting and rolling process with ??acquired inhibitor method?? during continuous casting and soaking was studied by thermodynamic calculation. The calculated results show that AlN is likely to precipitate in ferrite after solidification. However, MnS can precipitate only in the two phase region of ferrite and austenite. Meanwhile, MnS and AlN in the steel can not be completely dissolved during the soaking stage. In addition, the abnormal growth of primary grain is not obvious after high-temperature nitriding, which indicates the number of inherent inhibitor in the steel is relatively sufficient before nitriding.     

Prediction of Inhomogeneous Distribution of Microalloy Precipitates in Continuous-Cast High-Strength,Low-Alloy Steel Slab

Spatial distribution in size and frequency of microalloy precipitates have been characterized in two continuous-cast high-strength, low-alloy steel slabs, one containing Nb, Ti, and V and the other containing only Ti. Microsegregation during casting resulted in an inhomogeneous distribution of Nb and Ti precipitates in as-cast slabs. A model has been proposed in this study based on the detailed characterization of cast microalloy precipitates for predicting the spatial distribution in size and volume fraction of precipitates. The present model considers different models, which have been proposed earlier. Microsegregation during solidification has been predicted from the model proposed by Clyne and Kurz. Homogenization of alloying elements during cooling of the cast slab has been predicted following the approach suggested by Kurz and Fisher. Thermo-Calc software predicted the thermodynamic stability and volume fraction of microalloy precipitates at interdendritic and dendritic regions. Finally, classical nucleation and growth theory of precipitation have been used to predict the size distribution of microalloy precipitates at the aforementioned regions. The accurate prediction and control over the precipitate size and fractions may help in avoiding the hot-cracking problem during casting and selecting the processing parameters for reheating and rolling of the slabs.     

薄板坯连铸连轧工艺与硅钢生产

介绍了薄板坯连铸连轧工艺生产无取向硅钢和取向硅钢的工艺特征。重点比较了这一新工艺与传统工艺的不同点。指出了薄板坯连铸连轧工艺生产硅钢具有天然的优越性。     

高磁感取向硅钢生产技术与工艺的研发进展及趋势

 采用节能、环保、经济型的生产技术与工艺来制造高磁感取向硅钢目前已成为世界各大取向硅钢生产厂的研发热点。总结了国内外各大钢铁企业与研究机构采用低温板坯加热技术生产高磁感取向硅钢的开发及应用情况,概括了传统流程实现低温板坯加热技术的方法。介绍了薄板坯连铸连轧与双辊薄带连铸等短流程工艺生产高磁感取向硅钢的研发现状。在此基础上,探讨了高磁感取向硅钢生产技术与工艺的发展趋势及方向。     

Microstructure and precipitation in as cast low carbon Nb–V–Ti microalloyed medium thin slab

Abstract

The solidification structure, austenite and precipitates in a quenched compact strip processing (CSP) medium thin slab (170 mm thick) of Nb–V–Ti microalloyed steel have been studied. It was found that secondary dendrite arm spacing and austenite grain size are slightly larger than that of similar steel produced by CSP thin slab. This is partially attributed to the slower cooling rate caused by the increased slab thickness. On the other hand, the formation of carbonitride during solidification reduces the width of secondary dendrite arm spacing, while TiN particles and alloying elements in solution may inhibit the growth of austenite grain during solidification and subsequent cooling. In addition to the semidendritic, larger cubic and fine cubic precipitates, which can be observed in CSP thin slab, dendritic precipitates were also found in CSP medium thin slab.     

新日铁取向硅钢热轧边裂及其防止方法

新日铁针对取向硅钢热轧板存在的边裂问题，采取了电磁搅拌、连铸板坯直送边部加热、实施板坯边部压下、电磁感应加热、控冷控轧、控制热轧精轧开始温度和终了温度、最终道次压下率及加热温度、控制组织、减少边部与中间的温度差异、消除狗骨等一系列措施，取得了明显效果。     

V-N微合金化CSP带钢中的析出物研究

利用Gleeble 1500D热力模拟实验机,在实验室模拟了V-N微合金化CSP钢带的生产过程.实验结果显示,在连铸初期,TiN基本全部从钢中析出,而随着铸坯温度的降低,V开始以TiN为核心或单独形核析出,在铸坯均热后,大部分单独形核的V(C,N)趋于溶解,未溶解的则开始长大,而以TiN为核心的(Ti,V)(C,N)中的V部分溶解于钢中,V在粒子中的含量减少.在CSP连轧中,V(C,N)不断从钢中析出,全部析出物起阻碍奥氏体晶粒长大的作用,而含V颗粒还促进铁素体的形核,提高奥氏体/铁素体相变比率,细化最终的铁素体组织.