Mathematical model of deoxidization with post stirring in a combined blowing converter

Dissolved oxygen in the steel at the terminal of the converter smelting process is the main cause for the formation of oxide inclusions, and the high terminal oxygen content worsens the steel cleanness. However, post stirring in a combined blowing converter can promote the carbon-oxygen reaction in the liquid steel and reduce the dissolved oxygen content at the terminal of the converter smelting process. Thus, the mathematical model of deoxidization in the post stirring process was obtained, and the rationa...     

LD-BAr-CC工艺生产低碳铝镇静钢纯净度研究

研究武汉钢铁股份有限公司炼钢总厂四分厂LD-BAr-CC工艺条件下生产的低碳铝镇静钢的纯净度,分析各工艺阶段钢中显微夹杂、大型夹杂以及全氧、氮含量的变化情况。结果表明,在该厂现行工艺条件下,采用吹氩工艺可明显降低钢中夹杂物含量和全氧含量,全氧含量从精炼前的109.30×10-6降至30.75×10-6。各工序中钢的显微夹杂物主要为Al2O3和SiO2,这是脱氧产物和钢液二次氧化产物在钢中的残留物;大型夹杂物主要是Al2O3、SiO2以及硅铝酸盐等复合夹杂,与浮渣的卷入有很大关系。     

Al 脱氧弹簧钢钙处理过程中铝酸钙硫化物析出热力学分析

通过钢液与夹杂物间的热力学平衡计算,对Al脱氧弹簧钢钙处理过程中铝酸钙硫化物的析出行为进行热力学分析,探讨[Al]、[Ca]、[S]浓度和钢液温度对Al2O3夹杂物变性行为的影响。结果表明,1600℃钢液温度下,w[Al]＝0．03％时,Al2O3生成为低熔点12CaO ·7Al2O3时的 w[Ca]＞0．0034％,其值随钢液温度降低而减小,随铝含量增大而增大。CaS析出时的临界钙含量随钢液温度降低而显著减小,当w [S ]＜0．005％时,w[Ca]随w[S]变化而显著变化。要使钢中夹杂物控制在低熔点12CaO ·7Al2O3区域,需控制w [S]＜0．0037％,该值随钢液温度的降低或铝含量的增大而减小。     

重轨钢外来夹杂物特征的研究

人为地将保护渣、耐火材料、炉渣和钢锭模内残留物加入重轨钢中，采用金相显微镜及电镜能谱仪检测所形成夹杂物的特征。结果表明，不同的加入物所形成的夹杂物的能谱不同，从而可以根据夹杂物的特征确定夹杂物的来源。     

Effects of oxygen potential and flux composition on dephosphorization and rephosphorization of molten steel

The dephosphorization experiments of low phosphorus containing steel by CaO-based and BaO-based fluxes were carried out. The effects of the oxygen potential in molten steel and the BaO content in the slag on dephosphorization and rephosphorization of molten steel were analyzed. The results showed that the dephosphorization ratio of more than 50% and the ultra-low phosphorus content of less than 0.005% in steel were obtained by the three kinds of dephosphorization fluxes as the oxygen potential of molten steel higher than 400×10-6. Rephosphorization of molten steel was serious as the oxygen content of molten steel lower than 10×10-6. BaO-based fluxes can improve the dephosphorization effect and reduce the phosphorus pick-up effectively under the condition of weak deoxidization of molten steel (the oxygen potential is about 100×10-6), but can not prevent rephosphorization under the condi- tion of deep deoxidization of molten steel (the oxygen potential less than 10×10-6).     

低碳钢头坯洁净度研究

采用氧氮分析、金相分析、大样电解分析、扫描电镜及能谱分析等,研究LD—Ar站—CC生产的低碳钢头坯不同浇铸长度处的洁净度变化规律,并与正常坯洁净度水平进行对比分析。结果表明,头坯中T[O]和氮含量均随着浇铸长度的增加呈明显的下降趋势;头坯中显微夹杂物数量和大型夹杂物数量随着浇铸长度的增加大体都呈减少趋势;头坯中显微夹杂物主要来源于脱氧产物和二次氧化,大型夹杂物来源于二次氧化、结晶器卷渣、中间包卷渣和钢包引流砂;与正常坯洁净度相比较,头坯洁净度在浇铸长度大于3m以后与正常坯水平相一致。     

Inclusion variations and calcium treatment optimization in pipeline steel production

SiCa line and SiCaBaFe alloy were injected into liquid pipeline steel at the end of LF refining as calcium treatment,and samples were taken from the ladles,mould,and slabs.Analysis of Ca content and inclusions shows that Ca content in steel decreases obviously in the following process after calcium treatment; the compositions,morphology,and sizes of inclusions also vary much in the production; primary inclusions in the ladles prior to calcium treatment are mainly Al2O3 inclusions,but they turn to fine irregular CaS-CaO-Al2O3 compound inclusions after the treatment,then become fine globular CaO-Al2O3 inclusions in the mould,and finally change to a few larger irregular CaS-CaO-Al2O3 complex inclusions in the slabs.Thermodynamic study reveals that inclusion variations are related with the preferential reactions among Ca,Al2O3,and S and the precipitation of S in CaO-Al2O3 inclusions with high sulfur capacity.New evaluation standards for calcium treatment in high-grade pipeline steel were put forward according to the inclusion variations and requirements of pipeline steel on inclusion controlling,and the calcium process was studied and optimized.     

开发应用钢包渣还原处理技术提高钢的纯净度

通过对钢水二次氧化的分析,揭示了钢包渣对钢水二次氧化的主要作用.钢包渣还原处理技术的开发及应用,为降低钢水氧含量、降低板坯夹杂物进而提高产品质量起到了重要作用,同时促进了钢水进一步脱硫.     

Ti微合金三级锚链钢的生产试验

为提高三级锚链钢质量,设计该钢种化学成份,优化炼钢过程的脱氧、合金化及连铸工艺,结合钛微合金化及铸坯进保温坑缓慢冷却的工艺进行工业试验.结果表明,工艺过程控制较为合理,生产的三级锚链钢各项性能指标均达到国家标准要求,解决了三级锚链钢纵裂纹的问题.     

大型钢锭无铝脱氧工艺研究

研究了BOF+LF+VD-下注法生产大型钢锭流程采用无铝脱氧工艺、CaO-SiO2渣系的优点,以及在此工艺下如何实现钢锭的内在质量控制,满足钢锭在锻造、加工等后续工艺处理后的机械性能要求。试验结果表明,采用该工艺彻底解决了尖晶石夹杂物对钢的纯净度的影响,设计钢锭模钢水氢含量测定方法,实现了对浇注过程钢锭模内钢水气体含量的精确测定,确保大型钢锭内在质量较好满足后续产品需求。     

Study on Oxygen Content, Inclusions and Fatigue Properties of Bearing Steels Produced by Different Processes

The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continuous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0× 10-6, the carbon segregation (C/C0) is from 0.92 to 1. 10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.     

用硅铝铁合金代替铝脱氧

本文通过试验表明，用硅铝铁代替铝进行钢的终脱氧，钢材质量相当。而且具有烧损少、收得率高和降低生产成本的特点，获得了显著的经济效益和社会效益。     

包钢80 t转炉重轨高碳出钢工艺研究

阐述了饮钢80t转炉冶炼重轨从低碳出钢到高碳出钢的工艺流程，并得到了出钢碳含量与[H]，[O]关系图以及出钢温度与[H]的关系图。     

Determination of inclusions in liquid steel after calcium treatment

Nozzle blocking was eliminated by calcium-treated liquid steel through changing the chemical and phase composition of alumina inclusions in aluminium-killed steel.Three different methods were applied to determine the composition of inclusions in liquid steel:total oxygen content samples,sampling spoon samples,and "lollipop" steel samples.The results show that calcium modification of liquid steel influences the inclusion composition varying from 2wt% to 14wt% depending on the method used.The composition of i...     

Influence of calcium content on solid ratio of inclusions in Ca-treated liquid steel

1. IntroductionThe calcium treatment by wire feeding is applied asa routine process during steel making to eliminate noz-zle blocking [1-5]. Especially, it is an indispensabletechnology for producing pipeline steel [6-8].The calcium treatment can improve …     

稀土铈镁复合变质剂对SS400钢中夹杂物的影响

在实验和检验分析的基础上,以稀土铈、镁为微合金元素,加入到SS400钢中,探讨了变质处理对SS400钢中夹杂物的影响,对不同稀土铈、镁含量的SS400钢中夹杂物形态、分布和夹杂物等级情况进行对比研究.结果表明,稀土铈、镁可以使钢中夹杂物变质、细化并弥散分布.     

Behavior of Non-metallic Inclusions in Centrifugal Induction Electroslag Castings

In order to know the behavior of non-metallic inclusions in centrifugal induction electroslag castings (CIESC), non-metallic inclusions in 5CrMnMo and 4Cr5MoSiV1 were qualitatively and quantitatively analyzed. The largest size of inclusions in the casting and the thermodynamic possibility of TiN precipitation in steel were also calculated. The results show that sulfide inclusions are evenly distributed and the content is low. The amount of oxide inclusions in CIESC 4Cr5MoSiV1 steel is close to the ESR steel and lower than that in the EAF steel, and there are some differences along radial direction. Nitride inclusions are fine and the diameter of the largest one is 3-4 μm. With the increase of the centrifugal machine's rotational speed, the ratio of round inclusions increases and the ratio of sharp inclusions decreases. According to the experiment and the calculation results, it is pointed out that the largest diameter of non-metallic inclusions in the CIESC 4Cr5MoSiV1 casting is only 6.6 μm, and [N%][Ti%] in 4Cr5MoSiV1 steel should be controlled less than 4.4× 10-5 in order to further reduce the amount and size of TiN inclusions.     

马钢电弧炉弹簧钢60 Si2 MnA氧含量技术可行性研究

针对马钢100t电弧炉EAF→LF→RH生产弹簧钢60Si2Mn A的冶炼生产工艺流程,采取系统的取样、综合分析弹簧钢冶炼过程中全氧变化规律及影响因素,结果表明:在电弧炉-LF精炼-RH真空处理中,全氧含量基本是逐渐降低的;通过精炼全程底吹氩气,采用顶渣操作和高碱度(R=3.5)精炼渣,来降低渣中氧化物的含量及活度,均有利于降低弹簧钢中的全氧含量;钢水中氧含量最终可以控制在10ppm以内;     

BOF-LF-CSP与BOF-渣洗-CSP工艺生产Q235B钢中夹杂物对比分析

采用金相显微镜对BOF-LF-CSP与BOF-渣洗-CSP工艺所生产Q235B钢中非金属夹杂物数量和组成进行对比分析。结果表明,两工艺过程中各粒径颗粒夹杂物在总体上均减少,且粒径越小,其趋势越加明显;两工艺夹杂物总去除量分别为73.5%和72.3%,其中大部分夹杂物在转炉终点至LF前阶段被去除。BOF-渣洗-CSP工艺中夹杂物以Al2O3、FeS·MnS、CaO为主。两工艺过程中夹杂物演变规律相似,出钢渣洗效果明显,由此表明BOF-渣洗-CSP工艺生产可行。     

钾/钠在钢铁中的应用

自作者1981年发现钾/钠可使白口铁中碳化物团球化以来,在实验与生产应用中,对钾/钠在多种钢铁中的作用进行了一系列的研究。本文叙述研究结果,对冶金专业文献中钾/钠脱氧能力的评价同普通化学中论述相矛盾的现象提出了看法,并粗略地讨论了钾/钠在钢铁中的作用机理。认为钾/钠具有很强的脱氧作用,因而碳化物球团化应归功于脱氧,加入钾/钠后,液态铸铁结膜温度明显降低亦脱氧所致。文中还列出了各变质剂在铁水中脱氧作用的测试结果。