CN1670224A

CN1670224A - A stainless steel reduction dephosphorization agent

Info

Publication number: CN1670224A
Application number: CN 200410021379
Authority: CN
Inventors: 都祥元; 苏国跃; 孔凡亚; 杨柯
Original assignee: Institute of Metal Research of CAS
Current assignee: Institute of Metal Research of CAS
Priority date: 2004-03-15
Filing date: 2004-03-15
Publication date: 2005-09-21

Abstract

Disclosed is a stainless steel dephosphorization agent under reducing atmosphere comprising (by weight ratio) calcium Ca 25-55, balancing magnesium Mg, carbon C <0.1, manganese Mn <0.05, ferrum Fe <0.2, copper Cu <0.01, sulfur S <0.003, phosphor P <0.001. A chemical purity reagent CaF2 is employed as the fluxing agent. The invention can be applied for vacuum induction furnace for not only deep dephosphorization to stainless steel, but also for further deoxidization and desulfuration.

Description

A stainless steel reduction dephosphorization agent

技术领域；technology field;

本发明涉及不锈钢的制备技术，特别提供了一种不锈钢还原脱磷剂。The invention relates to the preparation technology of stainless steel, and in particular provides a reduction dephosphorization agent for stainless steel.

背景技术：Background technique:

不锈钢的返回料在炉料中的比例不断增加，因而使钢液中的磷含量不断上升。传统氧化法脱磷对于碳含量低于2％的钢水脱磷效果很差，而且不可避免的导致不锈钢中的合金元素Cr、Mn、Si的氧化损失；采用氧化法脱磷不可避免地由加入的CaO或BaO中带入了杂质元素碳，很容易使钢中的碳超标；即使采用目前常用的还原脱磷法，即用CaC₂、CaSi或AlCa脱磷，也容易带入碳、硅或铝等杂质，增加了脱除新引入的杂质的后期工序。The proportion of stainless steel return material in the furnace charge is increasing continuously, thus increasing the phosphorus content in molten steel. The dephosphorization effect of the traditional oxidation method for molten steel with a carbon content of less than 2% is very poor, and inevitably leads to the oxidation loss of alloying elements Cr, Mn, Si in stainless steel; the dephosphorization by oxidation method is inevitably caused by the added The impurity element carbon in CaO or BaO can easily make the carbon in the steel exceed the standard; even if the commonly used reduction dephosphorization method is used, that is, dephosphorization with CaC ₂ , CaSi or AlCa, it is easy to bring in carbon, silicon or aluminum. and other impurities, increasing the post-process of removing newly introduced impurities.

发明内容：Invention content:

本发明的目的是提供一种不锈钢还原脱磷剂，其可以在还原脱磷的同时，方便地脱除氧和硫，并且不提高碳的含量，从而大大降低钢中的非金属夹杂物。The purpose of the present invention is to provide a stainless steel reductive dephosphorization agent, which can conveniently remove oxygen and sulfur while reductive dephosphorization, without increasing the carbon content, thereby greatly reducing non-metallic inclusions in steel.

本发明提供了一种不锈钢还原脱磷剂，其特征在于化学组成为，重量百分比：Ca：25～55，Mg余量。The invention provides a reducing dephosphorization agent for stainless steel, which is characterized in that the chemical composition is: Ca: 25-55, Mg balance.

本发明不锈钢还原脱磷剂中，要求杂质C＜0.1，Mn＜0.05，Fe＜0.2，Cu＜0.01，S＜0.003，P＜0.001。In the reducing and dephosphorizing agent for stainless steel of the present invention, impurities C<0.1, Mn<0.05, Fe<0.2, Cu<0.01, S<0.003, P<0.001 are required.

在使用本发明不锈钢还原脱磷剂进行脱磷时，可以采用化学纯试剂CaF₂作为助熔剂。When using the reduction dephosphorization agent for stainless steel of the present invention for dephosphorization, chemically pure reagent CaF ₂ can be used as a flux.

众所周知，镁在钢中的溶解度高于钙在钢中的溶解度，1873K时钙在钢中的溶解度约为0.016％，而镁在钢中的溶解度约为0.04％，因此镁比钙有更大的脱磷潜力。Mg-Ca合金脱磷的热力学方程为：As we all know, the solubility of magnesium in steel is higher than that of calcium in steel. At 1873K, the solubility of calcium in steel is about 0.016%, while the solubility of magnesium in steel is about 0.04%, so magnesium has a greater solubility than calcium. dephosphorization potential. The thermodynamic equation for Mg-Ca alloy dephosphorization is:

$\begin{matrix} Ca Ca + + \frac{22}{33} [[P P]] = = \frac{11}{33} (({Ca Ca}_{33} {P P}_{22})) \\ Δ Δ {G G}_{11}^{o o} = = - - 440280440280 + + 167.4 167.4 T T - - - - - - - - ((11)) \\ Mg Mg + + \frac{22}{33} [[P P]] = = \frac{11}{33} (({Mg Mg}_{33} {P P}_{22})) \\ Δ Δ {G G}_{22}^{o o} = = - - 413067413067 + + 161.64 161.64 T T - - - - - - - - ((22)) \end{matrix}$

脱磷产物Ca₃P₂、Mg₃P₂在一定氧势下可发生(3)、(4)反应，可计算求得Ca₃P₂、Mg₃P₂的标准吉布斯自由能，从而求得反应(3)、(4)的吉布斯自由能。The dephosphorization products Ca ₃ P ₂ and Mg ₃ P ₂ can undergo (3) and (4) reactions under a certain oxygen potential, and the standard Gibbs free energy of Ca ₃ P ₂ and Mg ₃ P ₂ can be calculated, so that Obtain the Gibbs free energy of reactions (3) and (4).

${ΔG ΔG}_{33}^{o o} = = - - 3056219.88 3056219.88 + + 348.85 348.85 &Tgr; &Tgr; - - - - - - - - ((33))$

$Δ Δ {G G}_{44}^{o o} = = - - 2985152.94 2985152.94 + + 398.83 398.83 T T - - - - - - - - ((44))$

在标准状态下，反应(3)、(4)达到平衡时，可以得到平衡常数K₃、K₄的表达式为：In the standard state, when the reactions (3) and (4) reach equilibrium, the expressions of the equilibrium constants K ₃ and K ₄ can be obtained as:

$\begin{matrix} {K K}_{33} = = \frac{11}{{(({P P}_{{O o}_{22}}^{{Ca Ca}_{33} {P P}_{22}} / / {P P}^{θ θ}))}^{44}} - - - - - - - - ((55)) \\ {K K}_{44} = = \frac{11}{{(({P P}_{{O o}_{22}}^{{Mg Mg}_{33} {P P}_{22}} / / {P P}^{θ θ}))}^{44}} - - - - - - - - ((66)) \end{matrix}$

并利用公式 $\ln K = \frac{- {ΔG}^{o}}{RT},$ 可计算出反应(3)、(4)的临界氧分压分别为：and using the formula $\ln K = \frac{- {ΔG}^{o}}{RT},$ The critical oxygen partial pressures of reactions (3) and (4) can be calculated as:

$\begin{matrix} {P P}_{{O o}_{22}}^{{Ca Ca}_{33} {P P}_{22}} = = 44 \sqrt{exp exp ((Δ Δ {G G}_{33}^{o o} / / RT RT))} \cdot &Center Dot; {P P}^{θ θ} - - - - - - - - ((77)) \\ {P P}_{{O o}_{22}}^{{Mg Mg}_{33} {P P}_{22}} = = 44 \sqrt{exp exp ((Δ Δ {G G}_{44}^{o o} / / RT RT))} \cdot &Center Dot; {P P}^{θ θ} - - - - - - - - ((88)) \end{matrix}$

在标准状态下，根据以上计算可得到反应(3)、(4)在一定温度下的氧化脱磷与还原脱磷相互转化的临界氧势P_O2 ^Ca3P2和P_O2 ^Mg3P2，如表1：Under standard conditions, according to the above calculations, the critical oxygen potentials P _O2 ^Ca3P2 and P _O2 ^Mg3P2 for the interconversion of oxidative dephosphorization and reductive dephosphorization of reactions (3) and (4) at a certain temperature can be obtained, as shown in Table 1:

表1在一定温度下的氧化脱磷与还原脱磷相互转化的临界氧势 T(℃) 1450 1500 1550 1600 1650 1700 P_O2 ^Ca3P2(10^-12Pa)P_O2 ^Mg3P2(10^-11Pa) 0.0240.0375 0.1070.164 0.4470.648 1.732.34 6.178.51 21.021.0 Table 1 The critical oxygen potential of the interconversion between oxidative dephosphorization and reductive dephosphorization at a certain temperature T(°C) 1450 1500 1550 1600 1650 1700 P _O2 ^Ca3P2 (10 ^-12 Pa)P _O2 ^Mg3P2 (10 ^-11 Pa) 0.0240.0375 0.1070.164 0.4470.648 1.732.34 6.178.51 21.021.0

由以上计算可知，在标准状态下和炼钢温度范围内，体系氧分压分别达到10^-12Pa、10^-11Pa时，用钙或镁脱磷时，可以使钢液进行还原脱磷，而且趋势相同。因此我们可以认为当体系总的氧分压低于10^-13Pa时，可以采用Mg-Ca合金进行还原脱磷。From the above calculations, it can be seen that under the standard state and within the temperature range of steelmaking, when the oxygen partial pressure of the system reaches 10 ^-12 Pa and 10 ^-11 Pa respectively, when calcium or magnesium is used for dephosphorization, the molten steel can be reductively dephosphorized. And the trend is the same. Therefore, we can think that when the total oxygen partial pressure of the system is lower than 10 ^-13 Pa, Mg-Ca alloy can be used for reductive dephosphorization.

本发明考虑到作为还原脱磷主要元素的镁来源广泛：镁在地壳中储藏量丰富，其蕴藏量为2.7％，仅次于Al和Fe而占第3位。在大多数国家中都能发现镁矿石。海水中也还有丰富的镁，含量约为0.13％，可为人类提供取之不尽的镁资源。尤其值得一提的是，中国是世界上镁资源最丰富的国家之一，白云石矿产丰富，辽宁大石桥一带的菱镁矿储量约占世界的60％以上，矿石品位高达40％。这为镁合金和钢铁冶金的发展提供了极其有利的保证。The present invention considers that the source of magnesium as the main element of reductive dephosphorization is extensive: the reserve of magnesium in the earth's crust is 2.7%, which is second only to Al and Fe and occupies the third place. Magnesium ore can be found in most countries. Seawater is also rich in magnesium, with a content of about 0.13%, which can provide human beings with inexhaustible magnesium resources. It is especially worth mentioning that China is one of the countries with the richest magnesium resources in the world, and is rich in dolomite minerals. The magnesite reserves in Dashiqiao, Liaoning account for more than 60% of the world's total, and the ore grade is as high as 40%. This provides an extremely favorable guarantee for the development of magnesium alloy and iron and steel metallurgy.

本发明可以应用在真空感应炉上，对不锈钢进行深脱磷的同时，可以进一步脱氧和脱硫。脱磷率可以达到50％，脱氧、脱硫率在95％以上。The invention can be applied to a vacuum induction furnace, and can further deoxidize and desulfurize stainless steel while performing deep dephosphorization. The dephosphorization rate can reach 50%, and the deoxidation and desulfurization rates are above 95%.

附图说明：Description of drawings:

图1为脱磷后00Cr18Ni10的夹杂物形貌图。Figure 1 is the morphology of inclusions of 00Cr18Ni10 after dephosphorization.

具体实施方式：Detailed ways:

使用普通真空感应炉(不加正压)或电炉，第一步先将不锈钢返回料放入打结并烘烤好的MgO坩埚中，把颗粒小于φ2的脱磷剂Mg-Ca合金及助熔剂CaF₂按照质量百分比为4∶1的比例放入料斗中，然后抽真空至10^-4～10^-3Pa，送电加热至坩埚中原料全部熔化。精炼期结束后，向炉内充入一定量的氩气，并调整加热功率使钢液温度在1450～1500℃，中间间隔2分钟分三批加入脱磷剂Mg-Ca合金及助熔剂CaF₂，脱磷操作结束2分钟后再次抽真空。在浇注前控制浇注温度，匀速浇铸钢锭。Using ordinary vacuum induction furnace (without positive pressure) or electric furnace, the first step is to put the stainless steel return material into the knotted and baked MgO crucible, and put the dephosphorization agent Mg-Ca alloy and flux with particles smaller than φ2 CaF ₂ is put into the hopper at a ratio of 4:1 by mass percentage, then vacuumed to 10 ^-4 ~ 10 ^-3 Pa, and heated by power supply until all the raw materials in the crucible are melted. After the refining period is over, fill a certain amount of argon into the furnace, and adjust the heating power to keep the temperature of the molten steel at 1450-1500°C, and add the dephosphorizing agent Mg-Ca alloy and flux CaF ₂ in three batches at intervals of 2 minutes , 2 minutes after the end of the dephosphorization operation, vacuum again. Control the pouring temperature before pouring, and cast steel ingots at a constant speed.

实施例1Example 1

脱磷剂的成分为，镁Mg：73.1，钙Ca：26.6，碳C：0.042，锰Mn：0.012，铁Fe：0.14，铜Cu＜0.01，硫S：0.0028，磷P：0.001。The composition of the dephosphorization agent is: magnesium Mg: 73.1, calcium Ca: 26.6, carbon C: 0.042, manganese Mn: 0.012, iron Fe: 0.14, copper Cu<0.01, sulfur S: 0.0028, phosphorus P: 0.001.

根据还原脱磷工艺，在25Kg真空感应炉上对马氏体不锈钢2Cr13进行脱磷。脱磷前后C、O、S、P、Mg、Ca质量百分比含量对比，如表2：According to the reductive dephosphorization process, the martensitic stainless steel 2Cr13 is dephosphorized in a 25Kg vacuum induction furnace. The comparison of C, O, S, P, Mg, and Ca mass percentage before and after dephosphorization is shown in Table 2:

实施例2Example 2

脱磷剂的成分为，镁Mg：68.9，钙Ca：30.8，碳C：0.042，锰Mn：0.012，铁Fe：0.14，铜Cu＜0.01，硫S：0.0028，磷P：0.001。The composition of the dephosphorization agent is: magnesium Mg: 68.9, calcium Ca: 30.8, carbon C: 0.042, manganese Mn: 0.012, iron Fe: 0.14, copper Cu<0.01, sulfur S: 0.0028, phosphorus P: 0.001.

表2 2Cr13还原脱磷前后C、O、S、P、Mg、Ca质量百分比含量序号 C(％) S(％) P(％) O(％) Mg(％) Ca(％) 脱磷前 0.16 0.008 0.034 0.0049 - - 实施例1实施例2 0.0160.018 0.00080.0011 0.0110.014 0.00100.0011 0.0030.003 0.0050.003 Table 2 Contents of C, O, S, P, Mg, Ca in mass percent before and after reductive dephosphorization of 2Cr13 serial number C(%) S(%) P(%) O(%) Mg(%) Ca(%) Before dephosphorization 0.16 0.008 0.034 0.0049 - - Example 1 Example 2 0.0160.018 0.00080.0011 0.0110.014 0.00100.0011 0.0030.003 0.0050.003

实施例3Example 3

脱磷剂的成分为，镁Mg：64.2，钙Ca：35.6，碳C：0.071，锰Mn：0.0113，铁Fe：0.11，铜Cu＜0.01，硫S：0.0019，磷P：0.001。The composition of the dephosphorization agent is: magnesium Mg: 64.2, calcium Ca: 35.6, carbon C: 0.071, manganese Mn: 0.0113, iron Fe: 0.11, copper Cu<0.01, sulfur S: 0.0019, phosphorus P: 0.001.

根据还原脱磷工艺，在25Kg真空感应炉上对奥氏体不锈钢00Cr18Ni10进行脱磷。脱磷前后C、O、S、P、Mg、Ca质量百分比含量对比，如表3：According to the reduction dephosphorization process, the austenitic stainless steel 00Cr18Ni10 is dephosphorized in a 25Kg vacuum induction furnace. The comparison of C, O, S, P, Mg, and Ca mass percentage before and after dephosphorization is shown in Table 3:

实施例4Example 4

脱磷剂的成分为，镁Mg：61.6，钙Ca：38.2，碳C：0.059，锰Mn：0.011，铁Fe：0.14，铜Cu＜0.01，硫S：0.0022，磷P：0.001。The composition of the dephosphorization agent is: magnesium Mg: 61.6, calcium Ca: 38.2, carbon C: 0.059, manganese Mn: 0.011, iron Fe: 0.14, copper Cu<0.01, sulfur S: 0.0022, phosphorus P: 0.001.

表3 00Cr18Ni10还原脱磷前后C、O、S、P、Mg、Ca质量百分比含量序号 C(％) S(％) P(％) O(％) Mg(％) Ca(％) 脱磷前 0.014 0.030 0.0099 0.017 - - 实施例3实施例4 0.0150.014 0.00100.0011 0.00630.0051 0.00040.0006 0.0040.003 0.0050.004 Table 3 Mass percent content of C, O, S, P, Mg, Ca before and after reductive dephosphorization of 00Cr18Ni10 serial number C(%) S(%) P(%) O(%) Mg(%) Ca(%) Before dephosphorization 0.014 0.030 0.0099 0.017 - - Example 3 Example 4 0.0150.014 0.00100.0011 0.00630.0051 0.00040.0006 0.0040.003 0.0050.004

从表2、3中可以看出，脱磷率在30％～50％，而脱氧和脱硫率都在95％以上，大大减少了钢中的非金属夹杂物，而且碳元素在还原脱磷前后变化微小，镁、钙的残余量也在痕量范围内。It can be seen from Tables 2 and 3 that the dephosphorization rate is 30% to 50%, while the deoxidation and desulfurization rates are above 95%, which greatly reduces the non-metallic inclusions in the steel, and the carbon element is reduced before and after dephosphorization. The change is small, and the residual amounts of magnesium and calcium are also in the trace range.

图1为脱磷后00Cr18Ni10的夹杂物形貌图，可知精炼后夹杂物的平均体积分数fv值由1.15～1.9％，减小到0.3～0.6％，夹杂物平均半径由5～10um减小到3～5um。由此看出，Mg-Ca处理后的铸锭夹杂物尺寸明显变小，所占百分比同时明显减少，而形状和夹杂物成分基本相同。Figure 1 is the morphology of inclusions of 00Cr18Ni10 after dephosphorization. It can be seen that the average volume fraction fv value of inclusions after refining is reduced from 1.15 to 1.9% to 0.3 to 0.6%, and the average radius of inclusions is reduced from 5 to 10um to 3 ~ 5um. It can be seen from this that the size of the inclusions in the ingot after Mg-Ca treatment is significantly smaller, and the percentage is significantly reduced at the same time, while the shape and composition of the inclusions are basically the same.

Claims

1. A reducing and dephosphorizing agent for stainless steel, characterized in that the chemical composition is, in weight percentage: Ca25-55, Mg balance.

2. The reducing and dephosphorizing agent for stainless steel according to claim 1, wherein: C<0.1, Mn<0.05, Fe<0.2, Cu<0.01, S<0.003, P<0.001.