奥氏体不锈钢熔体氮溶解行为的研究

在实验室条件下，以304不锈钢为例，研究了奥氏体不锈钢熔体在不同温度和氮分压下气相渗氮过程中的氮溶解行为。实验发现，氮分压越大其氮的溶解度越大，而温度越高则氮的溶解度越小。分别从热力学和动力学方面分析，建立了热力学和动力学计算公式，并通过与实验数据对比发现其精确度均较高。     

不锈钢冶炼及凝固过程氮的控制

总结了氮在不锈钢中有害和有利正反两方面的作用。通过热力学计算和实测数据分析了温度和氮分压对不锈钢熔体中氮溶解度的影响,理论分析了不锈钢熔体吸氮和脱氮的动力学,指出了真空和高压分别是生产超低氮和高氮钢的主要方法。结合以往的研究成果和生产实践提出了生产超低氮铁素体不锈钢和高氮不锈钢的具体工艺技术措施。     

304不锈钢熔体氮溶解度的测定

介绍并比较了纯铁液中氮溶解度测定方法--直接法和间接法,并在经典的间接法的基础上,重新设计了气体氮的配气、控制和计量系统,以及渗氮的方式.用该方法测定了304不锈钢熔体在不同温度和氮分压下的氮的溶解度值.     

不锈钢控氮理论计算与实践

采用不同的氮在钢中的溶解度公式,计算了两种含氮不锈钢冶炼时所需要的氮气压力,并在50kg真空感应炉上,通过改变氮气压力,对两种不锈钢进行了氮含量控制实践。结果表明,采用Fujio测定值的理论计算值与试验实测值吻合度较高,同时给出了钢中氮含量的理论计算公式。     

Production of Nitrogen-Bearing Stainless Steel by Injecting Nitrogen Gas

 To replace nickel-based stainless steel, a nitrogen-bearing stainless steel was produced to lower the production cost stemming from the shortage of nickel recourses. Thermodynamic model to calculate the saturated nitrogen content in the stainless steel was developed and the model was validated by experimental measurements performed with a high temperature induction furnace. Nitrogen gas under constant pressure was injected into the molten steel with a top lance. Thus, the nitrogen was transferred to the molten stainless steel. The effects of chemical composition, temperature, superficial active elements and nitrogen flow rate on the transfer of nitrogen to the steel were investigated and discussed. The results showed that the dissolution rate of nitrogen in the molten steel increases with a higher temperature and larger nitrogen flow rate but decreases significantly with an increase in the content of surface-active elements. Alloying elements such as chromium and manganese having a negative interaction coefficient can increase the dissolution of nitrogen in the molten steel. It was also proposed that the primary factor affecting the final saturated nitrogen content is temperature rather than the dissolved oxygen content.     

氮在液态铁合金中溶解度的影响因素

由于高氮钢特殊的优异综合性能，使其在许多领域得到了应用。本文从压力、合金成分、温度三方面研究了影响氮在液态铁合金中溶解度的热力学因素。发现在设计了合适的合金钢成分后，增大系统的氮气分压可以明显地提高氮的溶解度，同时提出了利用铬当量法预测铁合金中氮溶解度的理论方法，从而为我国高氮钢的大规模生产提供理论依据。     

氮在6Cr21Mn10MoVNbN气阀钢熔体中的热力学分析

采用当量法对高氮钢钢液中的氮含量进行了推导,并用304不锈钢和316不锈钢的有关试验数据进行了验证,确定当量法可以进行高氮钢液氮溶解度的估算。随着合金含量的提高,氮在钢液中的溶解度会逐渐偏离Sieverts定律。通过热力学分析,得出了6Cr21Mn10MoVNbN气阀钢钢液中氮溶解度的估算公式。     

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In order to research the effect of nitrogen absorption with blowing N2 and adding FeCrN alloy to the liquid steel, the nick-free high nitrogen stainless steel (17Cr12Mn2Mo) was smelted on the 50kg vacuum induction melting furnace by changing the nitrogen pressure, temperature and adding FeCrN alloy. The result was compared to the theoretical calculation. The results show, stainless steel with certain nitrogen content can be smelted through changing nitrogen pressure and temperature, and the effect of increasing nitrogen pressure is much better than changing temperature, when the nitrogen pressure is up to 0??65MPa, the actual result is equal to the theoretical calculation; the effect of adding FeCrN alloy is better than increasing nitrogen press and controlling temperature, and the actual result is higher than the theoretical calculation.     

LF炉精炼AISI410不锈钢吹氮合金化研究

研究了40 t LF炉精炼AISI410不锈钢时,在常压下吹氮气增氮工艺(吹氮流量、吹氮时间及钢液温度)对AISI410不锈钢氮含量的影响,建立了AISI410不锈钢氮溶解度热力学计算模型。结果表明:钢中氮含量随着吹氮时间、氮气流量的增加而增大;常压下吹氮10 min,钢液含氮量可达到0.05%;随着氮流量增加钢液达到饱和的时间缩短,氮的溶解度随着钢液温度的降低而升高。应用热力学模型进行了分析,不同吹氮条件下氮溶解度实测值与热力学模型计算值较吻合。为LF炉精炼含氮不锈钢控制氮含量提供了理论依据。     

新型节镍奥氏体不锈钢的成分设计及生产试制

 综合传统AISI300系奥氏体不锈钢和高氮奥氏体不锈钢的优缺点,开发一种新型节镍奥氏体不锈钢。为了研究其最优成分和工业试制工艺,通过Thermo-Calc热力学计算软件设计成分、热轧试生产试验钢和微观测试方法分析试验钢。结果表明,新型节镍奥氏体不锈钢最优的成分范围(质量分数)为N0.2%~0.3%、C小于0.1%、Cr 18%~20%、Mn 8%~10%、Ni 1%~2%,Fe余量。在1 240 ℃等温会析出大量的铁素体,以至于在1 150 ℃开轧时不能消除,出现裂纹,在改进热轧温度后,控制铁素体含量,得到无裂纹热轧卷。     

利用氮化铬铁合金生产高氮无镍奥氏体不锈钢的研究

为在常压下能够生产出高氮无镍奥氏体不锈钢,选用了氮化铬铁合金作氮源,通过破碎、熔化微碳纯铁、加入锰合金及氮化铬铁合金颗粒,控制浇注时间和温度,以保证钢中有足够高的氮含量,测试结果表明,熔炼钢经固溶处理,可获得稳定的高氮无镍奥氏体不锈钢。     

碳饱和铁水中TiC/N析出热力学研究

摘要：高炉原料中添加一定量的含钛原料是有效延长高炉寿命的方法之一,钛溶解度与温度间热力学关系是指导含钛铁水有效护炉的理论依据。以某钢厂生铁和商业钛铁合金为原料,制备得到含钛铁液,利用高温共聚焦显微镜（CSLM）进行高熔点物相TiC/N在线析出研究,从而获得铁水中钛的溶解度与温度的对应关系。研究结果表明,当生铁中钛的质量分数分别为0.31%、0.36%和0.47%时,对应的析出温度分别为1715.1、1745.1和1814.1K。氮分压为105Pa时,钛的质量分数分别为0.07%、0.11%和0.25%的铁液中TiC/N析出温度分别为1535.6、1594.3和1729.8K。得到熔融生铁中,钛的活度系数与TiC析出温度之间的关系式;同理,氮分压为105Pa时,得到了钛的活度系数与温度间的关系式。     

低合金钢冶炼过程增氮行为分析

为提高中厚板系列低合金钢氮含量控制水平,从热力学、动力学角度全面分析冶炼过程增氮行为,并结合相关试验对影响钢液增氮的因素进行分析。结果表明,氮在钢液中的溶解度与温度、氮分压以及合金成分有关;气泡—钢液面上的吸附化学反应为限制性环节;当钢液中w(O)≥0.04%或w(S)≥0.06%,钢液吸氮基本停止;当转炉全程底吹氮强度不超过0.025 m3/(min·t)时,转炉终点氮含量可控制在10×10-6以内。     

液态铁基合金中氮溶解度的影响因素

从温度、压力、合金成分3个方面研究了影响氮在液态铁合金中溶解度的热力学因素,发现合金钢成分合适时,增大系统的氮气分压可以明显地提高氮的溶解度.同时,提出了利用铬当量法预测铁合金中氮溶解度的理论方法.     

C-HRA-5含Nb奥氏体耐热钢中氮的溶解行为研究

摘要：为实现C-HRA-5含Nb奥氏体耐热钢冶炼过程气相氮合金化精确控制,进行了0.033~0.1MPa氮气压力和1793~1853K下的气相渗氮实验,建立了含Nb耐热钢的氮溶解度模型和气相渗氮动力学模型。结果表明：通过考虑Cr、Ni与Nb对氮活度相互作用系数,含Nb奥氏体耐热钢的氮溶解度模型计算结果和实测值吻合良好,氮溶解度随冶炼温度升高而减小,随氮气压力增大而增大且符合Sieverts定律。气相 钢液间的渗氮动力学过程主要受界面化学反应速率控制,氮溶解反应速率常数随温度升高而增大,氮气压力则对其无明显影响,C-HRA-5钢的氮溶解反应速率常数可表示为lgk=2.1-7889/Tcm/(%·s)。     

高氮不锈钢的开发进展

加压冶炼高氮不锈钢是材料研究的一个新领域。介绍了高氮不锈钢的生产工艺及高压冶炼高氮不锈钢的主要设备。综述了欧美、日本等研发的高氮不锈钢的成分、力学性能及应用现状。由于受试验装备的限制,国内高氮不锈钢的研究与国外相比还有差距。针对高氮不锈钢具有多种优良性能,以及氮应用于对人体无害的生物、医疗材料方面前景广阔,提出医疗用高氮不锈钢将成为理想的生态材料。     

气体增氮法冶炼钒氮微合金钢

从理论上分析了钢液增氮的热力学、动力学影响因素,进行了BOF＋RH双联吹氮冶炼钒氮钢试验。结果表明,转炉底吹、RH喷吹均能有效增加钢液氮含量。RH真空度两段式控制既能满足控氢要求又能实现钢液搬出时较高的氮含量。BOF＋RH双联吹氮气工艺可以不加含氮合金冶炼钒氮微合金钢。     

AOD炉冶炼含氮不锈钢氮成分控制的研究

对氮在不锈钢熔体中溶解的热力学和动力学行为进行了理论分析,指出氮在不锈钢熔体中溶解度随钢水温度降低和铬、锰、钼含量增加而升高,而随着镍和碳含量的增加而降低;对AOD炉冶炼不锈钢吹氮合金化工艺控制模型进行了理论研究和实际应用,指出在AOD炉中氮含量随着钢水碳含量、温度、供氧强度、吹氩强度的变化而变化,该工艺适合冶炼钢种的氮含量小于该钢种在常压下理论氮溶解度的90%,为保证氮成分精度,以小于80 %为宜.     

Nitrogen Desorption in Molten Stainless Steel during Immersion Argon Blowing

The behavior of nitrogen desorption reaction in molten stainless steel for AISI 304 and 316 during immersion argon blowing through an immersed alumina nozzle with 3 mm in I.D. has been investigated by sampling method. Some kinetic parameters such as reaction order, rate constant and apparent activation energy of nitrogen desorption reaction for AISI 304 and 316 have been obtained. Results show that nitrogen desorption reaction from molten stainless steel for AISI 304 and 316 is the second order reaction. The rate constant at 1550 ℃ and 1580 ℃ for AISI 316 is 0.08407%-1·min-1 and 0.82370%-1·min-1, respectively. The rate constant at 1550 ℃ for AISI 304 is 0.4166%-1·min-1. The apparent activation energy Ea of nitrogen desorption reaction for AISI 316 is 2136.47 kJ/mol. This huge value of apparent activation energy verifies that the nitrogen desorption reaction has a complex and multistep reaction mechanism. The rate of nitrogen desorption reaction from molten stainless steel is mixed controlled by the desorption reaction of diatomic molecule nitrogen or of monatomic nitrogen from molten metal at the gas-metal interface and the mass transfer of nitrogen in molten metal. The rate equation of process for nitrogen desorption has been deduced.     

Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.