共查询到19条相似文献,搜索用时 171 毫秒
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对超低碳IF钢钛合金化后的非金属夹杂物进行了分析,研究发现钛合金化后的夹杂物主要为Al2O3和Al?Ti?O夹杂物,没有发现纯TiOx夹杂物。钢中生成的Al?Ti?O复合夹杂物从形貌上均可分为七种类型,四种具有Al2O3外层,另外三种无Al2O3外层。钛合金化后,钢中瞬态生成了大量无Al2O3外层的Al?Ti?O夹杂物,随后夹杂物表面生成Al2O3外层,导致有Al2O3外层的Al?Ti?O夹杂物数量比例逐渐增加至78.0%。热力学计算结果表明,随着钢中钛含量的增加,夹杂物的转变顺序为固态Al2O3→液态Al?Ti?O→固态Ti2O3。确定了Al?Ti?O夹杂物的生成机理过程分为两步:精炼过程钛合金化后,当钢液局部区域的钛的质量分数高于0.42%时,[Ti]与钢液反应瞬态生成Al2O3?TiOx或TiOx;随着精炼过程中钛元素的混匀,含TiOx夹杂物被钢中[Al]还原,Al2O3?TiOx和TiOx夹杂物逐渐转变,在夹杂物表面生成Al2O3。 相似文献
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针对国内某厂采用100 t电炉冶炼高碳铬轴承钢(GCr15),在生产过程中很难将铸坯全氧稳定控制在10×10-6以下的情况,采用全尺寸三维分析法和大样电解法对轴承钢铸坯中的夹杂物进行了分析研究。研究结果表明:轴承钢中大型夹杂物含量较高,主要是球型的Al2O3系夹杂和含K的块状夹杂,球型Al2O3类夹杂物主要来源于脱氧产物,含K的块状夹杂主要来源于结晶器保护渣的卷入。通过优化反应器流场和底吹氩气,可以促进大型Al2O3类夹杂物上浮和去除;对于含K的块状夹杂,通过优化结晶器流场和电磁搅拌来减少其卷入。显微夹杂物中Al2O3系夹杂物尺寸较大,钢液中存在少量的Mg或Ca都可以将Al2O3转变为尺寸较小的MgO·Al2O3、MgO或CaO·Al2O3·MgO系夹杂物。 相似文献
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运用热力学计算了X120管线钢含钛夹杂物在钢液中的析出条件,以X120管线钢钛的目标成分ω(Ti)=0.015%计算,当ω(Al)=0.000 35%~0.003 30%时,生成Al2 O3·TiO2; ω(Al)>0.003 30%时,则有Al2O3生成;要生成纯的MgO夹杂,钢中ω(Mg)>1.62×1013;ω(Mg)=0.0008%就可以生成2MgO·TiO2复合夹杂;X120管线钢没有纯的MgO夹杂,X120管线钢中会生成2MgO·Ti2O3、MgO·Al2O3、SiO2、Al2O3、Ti2O3、MnO等脱氧产物,这些脱氧产物还会和硫化物一起形成复合夹杂物.对夹杂物扫描电镜的观察与热力学计算的结果一致.在扫描电镜下观察了含钛夹杂物对铁素体的诱导,表明X120管线钢中含钛夹杂具有很好的诱导铁素体形核能力. 相似文献
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采用热力学计算和工业试验相结合的方法对不同硅含量下含钛奥氏体不锈钢全氧含量和夹杂物进行了研究。结果表明,随着精炼过程进行,含钛奥氏体不锈钢钢液中全氧含量、夹杂物数量呈逐渐减小的趋势。在AOD冶炼末期,含钛奥氏体不锈钢夹杂物类型为CaO-SiO_2-Al_2O_3-MgO,LF钛合金化前,夹杂物类型为CaO-Al_2O_3-MgO-SiO_2。LF钛合金化后,夹杂物类型主要为CaO-Al_2O_3-MgO-TiO_x球形夹杂物。热力学计算和试验结果具有较好的一致性。在其他条件一致的情况下,硅含量高的炉次跟硅含量低的炉次相比,钢液中氧含量低,夹杂物中钛含量低。 相似文献
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为开发含钛焊丝钢ER70S-G,对其冶炼过程中夹杂的数量、尺寸和类型进行研究。研究发现:在精炼过程中,钢中当量直径夹杂物的数目呈现逐渐降低的趋势;到中间包时,当量直径(5μm)夹杂物数目已经从包样的19.78个/mm2减少到1.66个/mm2;精炼过程夹杂物的平均直径呈逐渐降低的趋势,平均直径为2.05μm;精炼初期,钢中夹杂物类型主要是MnO-SiO_2夹杂,到加钛铁前,钢中的主要夹杂物转变为Ca O和Mg O,从加钛铁后到中间包期间,Al2O3-Ti_2O_3-Mg O系夹杂是钢中的主要夹杂物。 相似文献
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通过取样检测结合热力学计算,分析了钙处理对成品无取向硅钢中夹杂物特征及硫化物夹杂的析出机制的影响。结果表明,钢中尺寸大于3μm的有害夹杂物主要是AlN、MgO-SiO2、CaO-Al2O3-SiO2类复合夹杂物及其与MgS、MnS、CaS的复合析出物。钙处理钢中没有检测到单独的Al2O3、SiO2及铝酸钙类夹杂物。钙处理钢中形成的液态3CaO·Al2O3、MgO·SiO2和Al2O3夹杂物被精炼渣吸收,改性去除了钢中大尺寸Al2O3夹杂物。钙处理钢中尺寸大于3μm的氧化物夹杂主要是含CaO和(或)CaS的Al2O3-SiO2类夹杂。硫化物在MgO-SiO2类氧化物表面的析出有利于其形貌趋于规则。钢中不同形貌的AlN夹杂物呈多尺度分布,钙处理对大尺寸AlN的析出特性影响不大。氧硫化物及其与AlN复合析出并定向长大的过程,与其晶体结构有关。氧化物夹杂的硫容量决定了其与硫复合的难易程度。钙处理钢中CaS在氧化物表面呈局部包裹析出和局部吸附析出。 相似文献
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Cleanliness of Alloying Structural Steel 总被引:1,自引:0,他引:1
Alloying structural steel used for mechanical structures has a high requirement for cleanliness because its failures are greatly affected by non-metallic inclusions and total oxygen content in steel. It has been reported by some steelmaking plants to have some problems in controlling total oxygen content and inclusions during alloying structural steel production. For this purpose, cleanliness control in 02C-03Si-06Mn-1Cr-02Mo steel was investigated. Firstly, low melting temperature zone (≤1873 K) of CaO-Al2O3-MgO system and formation condition of low melting temperature inclusions were investigated through thermodynamic equilibrium calculation. On this basis, industrial tests were carried out. Through sampling at different stages, transformation of oxide inclusions and change of total oxygen content in steel were studied. The results show that: in order to form CaO-Al2O3-MgO system inclusions with low melting temperature, mass percent of Al2O3, MgO and CaO in inclusions should be controlled from 376% to 708%, 0 to 174% and 255% to 606%; For the condition of 1873 K and 005% (mass percent) dissolved aluminum in steel, the activities of dissolved oxygen, magnesium and calcium should be controlled as 0298×10-4-2×10-4, 01×10-5-40×10-5 and 08×10-8-180×10-8 respectively. With secondary refining proceeding, average total oxygen content and inclusion amount decrease, the type of most inclusions changes from Al2O3 after tapping to Al2O3-MgO after top slag is formed during ladle furnace refining and finally to CaO-Al2O3-MgO after RH treatment. In the final products, average total oxygen content was 127×10-6 and most inclusions were in spherical shape with size less than 5 μm. 相似文献
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With the process measures including using low titanium hot metal, alloys and slagging materials, eccentric bottom tapping and alloying in tapping in EAF steelmaking, using Si-Al compound deoxidation and CaO-MgO-SiO2 -Al2O3 slag series with basicity 3 ~5 in LF refining,30 Pa VD treatment and shielding casting,the analysis results of Φ150 mm forged bar are oxygen content in GCrl5 bearing steel being 4.5 X 10-6 ~9 x 10-6 ,Ti content 0.0010% ~0.0015% with minor 5 μm TiN inclusions to meet the quality requirement for super grade quality low titanium bearing steel. 相似文献
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含钛焊丝钢GF50-G(/%:0.08C,0.83Si,1.55Mn,0.014P,0.012S,0.19Ti)生产流程为80 t顶底复吹转炉-LF-160 mm×160mm方坯连铸,在浇注过程中经常出现水口结瘤现象。扫描电镜和能谱仪对水口结瘤物的分析得出,结瘤物主要物相为TiO2。水口结瘤的热力学计算表明,为避免钛脱氧产物被[Al]还原形成铝钛系夹杂物,应控制[Als]在0.008%以下。根据生产实践,将中间包钢水温度从1542℃提高至1 550℃控制[Alt]≤0.010%、加钛铁前使[O]≤15×10-6、减少钢水的二次氧化能够防止水口结瘤、连浇炉次从3~4炉提高到8~10炉。 相似文献
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为进一步提升RH精炼的冶炼效率,更好与高拉速连铸相匹配,对RH冶炼IF钢过程中加Ti时机和纯循环时间对夹杂物的影响开展了试验研究。结果表明,钢液中T.O质量分数在加Al 5 min后小于0.003 0%;夹杂物的数密度在合金化4~5 min后具有最小值,随后增加纯循环时间,夹杂物的数密度无明显变化。在300 t RH工业生产实践中,Al-Ti间隔时间为2 min、纯循环时间为5 min和Al-Ti间隔3 min、纯循环4 min的处理工艺可以保证钢液中的夹杂物充分上浮去除,夹杂物的数密度为0.7~0.8个/mm2,可以实现RH的高效化精炼。在Al-Ti间隔时间大于1 min、纯循环时间大于3 min的操作条件下钢液中未检测到尺寸大于50μm的夹杂物。基于以上工艺优化,IF钢的RH真空处理时间已经降低至20 min。向钢液中加入Al后主要形成Al2O3夹杂物,加入钛铁合金化后钢液中会形成富[Ti]区域,[Ti]将Al2O3还原而生成Al-Ti氧化物。随着[Ti]在钢液内的扩散以及... 相似文献
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《钢铁研究学报(英文版)》2011,(Z2):341-346
This paper aims at generally studying on the inclusions of ZGG06Cr13Ni4Mo ultra-low carbon stainless steel used for large scale hydraulic turbine sets. On the basis of analysis the industrial test samples, thermodynamic software FactSage is used to study inclusions transformation process in CaO-SiO2-Al2O3-MgO system while stainless steel is been smelting. The results illustrate the inclusions melting points and plasticity variation law. The reasonable inclusions plasticity controlling area is found out in low melting point. The melting point is up to 1280℃ While MgO weight concentration is 10% in CaO-SiO2-Al2O3-MgO system, SiO2, Al2O3 and CaO in inclusions are in weight concentration range of 50-70%, 10-20% and 10-40%, respectively. For purpose of gaining low melting point inclusions, silicon alumina radio in deoxidant should be controlled between 2-5 for ultra-low carbon stainless steel refining in industry. 相似文献
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通过电弧炉兑60%铁水,大量换渣操作,使用低钛合金控制电弧炉终点[Ti]≤7×10-6,LF精炼采用低钛脱氧合金化材料,控制LF终点[Ti]≤30×10-6,VD 27 min处理,控制中间包钢水过热度20~30℃全程保护浇铸等工艺措施,成功试生产出S355NL风电法兰用钢Φ500~800 mm连铸坯(/%:0.14~0.15C,0.21~0.23Si,1.30~1.33Mn,0.03~0.04Nb,≤0.003Ti,0.04~0.05V,≤0.010P,≤0.003S,0.02~0.04Alt)。检验结果表明,该钢锻件的综合机械性能良好,-50℃冲击功为87.4~100.3 J,用户产品无损探伤合格率达99.5%。 相似文献
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钛稳定化321奥氏体不锈钢(/%:0.04~0.08C,0.40~0.70Si,0.80~1.50Mn,≤0.035P,≤0.005S,17.0~18.0Cr,9.0~9.5Ni,0.20~0.40Ti,≤0.020 0N)的生产流程为90tEAF-45t AOD-LF-180mm×1 238 mm板坯连铸。该钢在浇铸过程中易产生水口结瘤和结晶器钢水中出现"结鱼"。根据TiN析出规律的分析,得出为降低TiN在钢水中的析出,应控制[N]≤0.015 0%,[Ti]≤0.25%,中间包钢水温度~1500℃。通过AOD全程采用超纯Ar搅拌,钢包中渣层厚度150 mm,[O]为15×10-6~20×10-6,控制[N]~110×10-6,采用碱度0.75,1300℃粘度0.165 Pa·s的保护渣等工艺措施,使Ti回收率由原40%提高到52%,成品N含量由0.0140%降至0.010 5%,浇铸结束后水口内径由42 mm增至50 mm,轧制缺陷率由改进前3.5%降至1.2%。 相似文献