共查询到18条相似文献,搜索用时 265 毫秒
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超纯轴承钢的精炼工艺 总被引:1,自引:0,他引:1
通过控制电炉(供氧强度、渣中氧化铁比例、出钢挡渣率、出钢钢液的氧活度)、钢包炉(精炼渣系、脱氧剂、钢液温度、精炼时间、底吹氩压力、精炼钢包耐火材料的选择、铁合金种类的选择)、真空脱气(真空度、真空时间、底吹氩压力)的工艺参数以及真空后的软吹氩搅拌、并采用IPAS系统和控制钢液浇铸速度,使超纯轴承钢(SFGCr15)的w(S)、w(Ti)、w(O)分别达到0.003%、0.001 2%和0.000 7%以下,钢中非金属夹杂物也处于较好水平,满足了国际顶尖轴承厂家对轴承钢的超纯要求. 相似文献
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众所周知,降低钢中有害气体和非金属夹杂物,是提高质量减少钢锭缺陷的重要途径之一。因此,近十几年来,钢水在炉外进行处理的工艺已在国内外的炼钢界引起广泛的注意。炉外处理的方法有许多种,如真空脱气、大罐吹氩、电磁搅拌和钢锭模吹氩等。目前在炼钢生产中,应用最普遍的,要属前两种了,它在许多科技文献中已有论述,肯定了它们的经济效果。这里仅对后一种方法,钢水在钢锭模中吹氩处理,予以探讨。一、在钢锭模中吹氩精炼的理由 1.真空脱气法,去除钢中气体和非金属夹杂物,是相当有效的,能显著改善钢的质量。但是由于它的设备比较庞大,建设费用较高,工艺操作复杂,今天在一般的钢铁厂,不是轻易能够采用的。对比之下,采用 相似文献
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通过VD真空脱氢工业实验,用回归的方法确定了脱氢速度方程及其传质系数、吹氩气量计算方程和搅拌功。在真空条件下氩气泡压力与钢液面的压力相差很大,由实验结果给出了真空脱气时,氩气泡压力VD终点钢液中氢含量的经验关系式,进而得到了确定氩气量的经验关系式工艺实验得到的参数为包钢在连铸重轨钢生产中进一步降低能耗和提高质量提供了基础数据。 相似文献
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钢液的炉外精炼与氧气转炉炼钢和连续浇注一起,是近三十年来黑色金属冶炼技术发展中最重要的几项成就。自1950年氩气搅拌和1952年真空脱气开始用于钢包精炼以来,其它如渣洗、电磁搅拌、电弧加热、吹氧等手段,也陆续用于精炼过程,从而出现一系列炉外精炼工艺。近年来,钢液的炉外精炼技术仍不断发展,其中最受重视的新发展是利用氩 相似文献
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大冶钢厂在较短时间内建成投产了一台VD装置——YG型18吨钢包炉的首期工程。该设备的主要特征是:真空室内钢包吹氩脱气;滑动水口结构可以实现对钢流进行气体保护;钢包上的吹氩管路在真空室内以自动方式接通;采用立柱支承的旋转揭盖形式;集中传动的全液压传动系统;布置紧凑的真空泵系统;热循环式钢包烘烤器等。本装置准备发展为一罐二盖的VAD/VOD炉型。 相似文献
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基于相似的动力学机理,利用水溶液中溶解氧的去除过程模拟了钢液的真空脱气行为. 在负压25 kPa条件下发现,容器壁面或测氧探头表面会析出大量细小气泡,这一现象与以往脱气数学模型假设的内部脱气反应非常类似;为了验证内部脱气位点的存在,通过引入机械搅拌,对溶池表面和内部脱气速率进行了分析计算. 实验结果表明,在整个脱气过程中溶池表面脱气速率很低,内部脱气位点析出的气泡会极大地提高溶解氧的去除速率,尤其当真空压力为25 kPa时,其脱气速率约为自由表面的脱气速率的10倍,但内部反应仅局限于脱气的初始阶段,即高溶解氧浓度范围内. 另外,水溶液中溶解氧的去除为一级反应过程,其体积传质系数(k · A · V?1)为常数,因此可以利用溶解氧在水溶液中的去除过程模拟钢液的真空脱气行为. 为了描述真空压力和吹氩流量对k · A · V?1的影响,引入搅拌动能密度(ε)的概念,通过线性回归得到了lg (k · A · V?1)与lg ε之间的函数关系,并与以往的模拟研究进行了对比. 相似文献
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The degassing of 09Г2C steel produced in an arc furnace and treated in a ladle–furnace unit at AO Uralskaya Stal is analyzed. The vacuum-treatment parameters that determine the effectiveness of hydrogen removal from the steel are identified: the depth and duration of vacuum treatment; the argon flow rate; the steel temperature; the thickness of the slag layer; and the free board in the vacuum chamber. The hydrogen content changes most significantly when the degassing time is increased to 20 min. Longer treatment is not recommended. The greatest effect of the residual pressure in degassing is observed with simultaneous decrease in the minimum pressure to 2 mbar. Vacuum treatment of the steel is considerably impaired with increase in the residual pressure. Hydrogen removal is improved with increase in the steel temperature to 1600–1620°C, but slows considerably at higher temperatures. The influence of the vacuum-treatment parameters is established quantitatively, and a regression equation is derived for predicting the results of hydrogen removal and selecting the parameter values corresponding to specified hydrogen content in the steel. Vacuum-treatment parameters that permit the economical production of steel with 2.1 ppm are determined: steel heating before vacuum treatment by 100–110°C; vacuum treatment for 20 min at a pressure no higher than 1.5 mbar in the vacuum chamber; argon flow rate 0.05 m3/t. The temperature losses of the metal are determined by the total treatment time, consisting of the active degassing time and the auxiliary time (the preliminary evacuation time), which depends on the capabilities of the equipment and the organization of the process. The minimum residual hydrogen content in the steel for the given equipment (1.6 ppm) is ensured by vacuum treatment for 40 min at a pressure no higher than 1 mbar in the vacuum chamber, with preliminary heating of the steel by 120–125 °C and with an argon flow rate up to 0.072 m3/t. 相似文献
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The development of a matured metallurgical process allows the reduction of the sulphur, nitrogen, hydrogen and total oxygen content to the lowest values in only one secondary metallurgical step during treatment in a ladle tank degassing unit. By careful adjustment of a lime-saturated ladle top slag at the beginning of the vacuum treatment, it is possible to obtain a desulphurization degree of more than 95%. The process of nitrogen removal by a stirring gas can be described with a dynamic model in excellent agreement with plant trials. The nitrogen content after vacuum treatment depends mainly on the nitrogen content before vacuum, the stirring gas quantity and the sulphur content. The achievable hydrogen contents mainly depend on the stirring gas quantity and dehydrogenisation can be described by the same model used for denitrogenisation. By a cleanliness stirring after the vacuum treatment under a nearly SiO2-free-, lime-alumina slag, saturated with lime, the total-oxygen content can be lowered to less than 20 ppm. 相似文献
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通过水模型研究了VD精炼过程的钢渣混卷行为, 定义了钢渣临界半混和临界全混状态, 并对不同底吹气量、真空度、底吹位置下的混合状态进行了研究;分析了临界搅拌功率和流场稳定性对混卷行为的影响.结果表明:在实验条件下, 临界半混和临界全混气量随着真空度的增大而减小;2/3R双孔底吹位置的临界气量大于2/3R+中心孔底吹位置的;并基于导出的真空度与底吹气量拟合公式, 外推出真空度为67 Pa时实际生产过程中的临界气量;VD过程钢包流场特性主要受底吹位置影响, 并进一步影响混卷行为, 在稳定性流场中当钢渣混合达到同一状态时, 搅拌功率几乎是定值. 相似文献
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