Inclusion characteristics of stainless steel castings

The characteristics of non-metallic inclusions in 347 stainless steel samples taken during a net-shape casting process after different holding times and melting temperatures were investigated using electrolytic extraction and polished cross-sections. The inclusions can be classified into three groups: oxides, composite inclusions and sulphides. Within the first two groups the inclusions were subdivided based on their morphology into the following categories: spherical, irregular and clusters. As the temperature decreased, sulphide and NbC precipitated within the steel melt as well as on the surface of existing oxides. The number density and area fraction of inclusions as well as the total oxygen contents increased with higher melt temperatures and longer holding times. The results obtained from thermodynamic calculations carried out using the FactSage? commercial software agreed well with the experimental observations. In addition, it has been concluded that turbulent collisions are the dominant mode for the growth of inclusion clusters.     

Effect of alloy addition on inclusion evolution in stainless steels

The number, morphology, size and composition of inclusions after deoxidation and alloying in Ti-stabilised stainless steel were investigated. This was carried out by electrolytic extraction of inclusions from steel matrix, followed by microscopic examination. It was found that after the addition of ferrosilicon and manganese, and later aluminium, the composition of inclusions changed from manganese silicate-rich inclusions to alumina-rich inclusions. After tapping and titanium wire feeding, three types of TiN inclusion morphologies were observed, single, twinned and clusters. Both the turbulence and Stokes' collision mechanisms play a considerable role in the formation of TiN clusters.     

镀锡基板线状缺陷控制

采用扫描电镜对镀锡基板表面线状缺陷进行了分析,结果发现,造成镀锡基板表面缺陷的主要原因为保护渣卷入和氧化铁皮残留。通过对镀锡基板生产工艺进行分析,得出：控制连铸过程铝损不大于0.0050%、液面波动控制在±2.5mm、控制板坯入炉温度不小于200℃,合理控制连浇炉数,增大拉矫破鳞机弯辊插入深度,可以大幅减少镀锡基板表面线状缺陷的产生。     

吹氩板坯连铸结晶器内钢水流态

 采用1[∶]1水模型和工业插钉法研究了吹氩板坯连铸结晶器内钢水流态,并讨论了通钢量、吹氩量、水口浸入深度与水口结构对结晶器流态的影响。水模型结果发现,结晶器内宏观流态主要包括双股流和单股流,钢水通量和吹氩量是影响结晶器内钢水流态的决定性因素。为得到双股流,应采用高通钢量和低吹氩量,缩小断面、增大浸入深度和使用凸底水口有利于双股流形成。基于水模型结果,为维持结晶器内双股流态,在实际浇铸中提出减少连铸过程吹氩量低于临界吹氩量,在宽断面和低拉速下使用凸底水口等措施。工业插钉试验结果与水模型吻合较好,这表明水模型结果可指导现场浇铸实践。     

近20年全球锌铝镁镀层钢板技术专利分析

 采用Orbit专利分析平台,对锌铝镁镀层钢板领域全球专利发展趋势、主要国家及重点创新机构的专利布局和技术领域研发进行了分析。对20年来全球锌铝镁镀层钢板领域重要专利及技术发展趋势进行了梳理,对国外知名钢铁企业锌铝镁镀层钢板最新专利技术趋势进行了剖析。国外钢铁企业在中国申请公开锌铝镁镀层钢板专利较多集中在日新制钢、新日铁住金、JFE公司。     

100t顶底复吹转炉底吹透气砖分布对钢液流场影响的数值模拟

利用Fluent流体软件,研究钢厂100 t顶底复吹转炉底吹透气砖数量（14）和分布对钢液流场及混匀时间的影响。结果表明,底吹砖数量和布置不同时,熔池的流动形成及搅拌效果也不相同;在气体总流量（100m³/h）相同的情况下,单透气砖钢液混匀时间最长,为380 s;两块底吹砖非对称对角分布时,钢液的混匀时间最短,为204 s;其次为4块底吹砖平面对称分布结构,混匀时间为255 s。     

板坯连铸38 t扩容中间包控流装置优化的数值模拟和应用

通过数值模拟,对钢厂250 mm×2 000 mm板坯连铸原29 t扩容至38 t中间包进行控流装置优化。研究了挡墙、挡坝的个数和位置对中间包内钢液流场及停留时间分布(RTD)曲线的影响,综合考虑了中间包冶金效果及生产成本,为现场提出了稳流器+挡墙+挡坝控流装置的最优设计方案,该方案使中间包活塞区比例达到77.1%,死区比例降至4.2%。现场采用该结构后非稳态浇铸期间生产的管线钢非金属夹杂物合格率由88%提高到95%,明显提高了中间包的冶金功能。     

钢铁企业综合节能新概念IESM

通过在钢铁企业各生产环节中实施一系列节能技术,如高炉压差发电TRT,烧结余热发电,转炉饱和蒸汽发电,焦炉余热发电等,为企业量身定做一个综合节能工程模型,以降低企业综合成本为出发点,同时调整企业的产品结构与经营布局,解决企业热、气平衡问题,从而实现节能减排,提高企业的综合效益,提升企业的产业竞争力。     

250～320 mm连铸板坯堆垛缓冷过程仿真计算

L245、D36、X70等钢种连铸板坯生产流程为铁水预处理-100 t转炉-LF-RH-250～320 mm×2000 mm板坯连铸。当铸坯人炉温度为650～700℃,因AlN在晶界析出,在轧制过程钢板易出现爪裂,当铸坯入炉温度控制在500～550℃则可避免钢板爪裂。通过ANSYS有限元软件,对板坯堆垛温度场和降温速率进行数值模拟。模型计算结果表明,250 mm和320 mm厚铸坯分别堆垛12 h和24 h后,可使堆垛中心铸坯表面温度达到600℃以下,现场实测值与模拟结果相同。     

高风温低燃料比高炉冶炼工艺技术的发展前景

分析了当前高炉炼铁技术面临的形势和挑战,提出了当代高炉炼铁技术的发展目标。阐述了高风温、富氧 喷煤对高炉炼铁的意义和作用。重点分析和论述了实现高风温和高富氧大喷煤的关键技术。提高风温、提高富氧 率、增加喷煤量是降低燃料消耗、节约生产成本和实现可持续发展的重要保障。在高风温、低燃料比冶炼条件下, 当代高炉炼铁技术具有广阔的发展前景。