Thermodynamic Properties of Mn-C Melts

Carbon solubility in Mn-Fe melts（xMn=0.161-0.706,xFe=0.034-0.633）was measured experimentally at various temperatures.By thermodynamic derivation and calculation,the relationship between activity coefficient of carbon in infinite dilute solution of manganese in Mn-C system and temperature was obtained.Using Gibbs-Duhem relationship,the experimental results of this study,and experimental data reported in references,the relationship between other thermodynamic properties in Mn-C system and temperature were obtained by thermodynamic derivation and calculation.     

Thermodynamic Properties of Carbon and Manganese in Mn-C and Mn-Fe-C Melts

Carbon solubility in Mn Fe melts （xMn =0. 083-0. 706, XFe =0. 034-0. 715） was measured experimentally at various temperatures. By thermodynamic derivation and calculation, the relationship between activity coefficient of carbon in infinite dilute solution of manganese in Mn-C system and temperature was obtained. Using Gibbs-Duhem relationship, the experimental results of this study, and experimental data obtained by strict thermodynamic derivation and calculation in references, the relationships between other thermodynamic properties （εCC, εCCC, εCFe, εCCFe, and εCFeFe） in Mn-Fe-C system and temperature were obtained.     

Mn-C系活度相互作用参数与温度关系的研究

实验测定了不同温度下C在Mn-Fe熔体中的溶解度。通过采用溶液的相互作用参数模型,结合实验结果,进行了严格的热力学推导与计算,获得了在1 623～1 748 K温度范围Mn-C系中εCC和εCCC与温度的关系式。     

Co-Cr系相平衡的热力学计算和fcc相的磁性诱导相分离

Two-phase equilibria between the ferromagnetic fcc and the paramagnetic fcc phase from 800 ℃ to 900 ℃ in the Co-rich region have been detected by the diffusion couple technique. Two phase separation region of the fcc has been confirmed along the Curie temperature. The phase equilibria including the present results and the thermodynamic data of the Co-Cr system reported in the literature were analyzed on the basis of the thermodynamic evaluation. A set of thermodynarnic values for the liquid, fcc, hcp, bcc, sigma phases was obtained. The calculated phase equilibria were in good agreement with most of the experimental data.     

Mn-C系活度相互作用参数的研究

实验测定了不同温度,C在Mn-Fe熔体中的溶解度。引用溶液的相互作用参数模型,结合本文的实验结果,引用文献报道的实验数据,通过严格的热力学推导与计算,获得1623～1748K范围适用的Mn-C系中εCC和εCCC与温度的关系式。     

Thermodynamic Properties of Fe-C-N and Fe-C-B-N Melts

The saturated solubility of carbon and nitrogen in Fe-C-N and Fe-C-B-N melts was measured experimentally at 1 485℃ to obtain the activity interaction coefficients between components in these melts. A new method was used to treat experimental results. Using thermodynamic derivation and calculation, some important interac- tion coefficients between components in these melts were obtained.     

Mn-C系活度相互作用参数与温度的关系

实验测定了不同温度下C在Mn-Fe熔体中的溶解度。引用溶液的相互作用参数模型,结合实验结果,引用文献报道的实验数据,通过严格的热力学推导与计算,获得1623～1748K范围适用的Mn-C系中εCC,ρCC和ρCC,C与温度的关系式。计算结果表明,这些关系式既能满足Gibbs-Duhem方程的必要条件εCC+2ρCC+3ρCC,C=0,又能满足C含量高时体系稳定的必要条件1+εCCxC+2ρCCxC2≥0。     

锰铁合金真空氧化脱磷过程成分变化研究

研究了在真空感应炉中锰铁合金氧化脱磷过程的脱磷和合金成分变化。结果表明，采用BaCO3基熔渣对锰铁合金真空氧化脱磷时，在实验的脱磷渣组成和真空度10kPa条件下，随着锰铁合金硅含量的增加，脱磷率和锰损下降；随着脱磷渣量的增加，锰铁脱碳量、脱磷率升高，锰损下降，最大脱磷率达42．60％，对应锰铁损为-0．30％，可达到锰铁合金的氧化脱磷保锰的目的。     

固溶处理对00Cr27Ni7Mo5N不锈钢的组织及力学性能的影响

 研究了不同固溶处理温度对特超级双相不锈钢00Cr27Ni7Mo5N组织及力学性能的影响。采用光镜、扫描电镜、能谱仪、显微硬度、冲击和拉伸测试等手段研究σ相的析出规律及其对力学性能的影响。运用Thermo-Calc热力学软件计算00Cr27Ni7Mo5N相含量随温度的变化,并与测试结果进行对比分析。研究结果表明,当固溶温度在800～1050℃之间,00Cr27Ni7Mo5N有大量金属间化合物σ相析出,导致钢的强度和硬度增加,塑韧性显著下降。当固溶温度在1070～1200℃时,钢中σ相溶解,钢的塑韧性提高,硬度下降。1100℃固溶处理时,00Cr27Ni7Mo5N具有最佳的综合力学性能。     

熔融高炉渣纤维化过程中析晶行为研究

以高炉渣为研究对象,采用Factsage热力学软件模拟高炉渣冷却过程中矿物开始析出温度、矿物的析出种类及含量;采用熔体物性综合测定仪研究高炉渣降温过程中的黏度变化;采用X射线衍射仪(XRD)和场发射扫描电子显微镜(SEM)研究高炉渣不同温度下的矿物组成和显微结构。结果表明:高炉渣冷却过程中,1 350℃开始析出晶体,析出的主晶相为钙铝黄长石(Ca_2Al_2SiO_7)和镁黄长石(Ca_2MgSi_2O_7)。此外,熔融高炉渣成纤适宜的温度区间为1 350~1 371℃。     

Na2WO4溶液的Pitzer参数及应用

利用Pitzer电解质溶液理论,回归25℃、252℃、301℃、352℃条件下Na2WO4和0~350℃范围内NaOH溶液的Pitzer参数。在不考虑混合电解质相互作用系数的情况下,利用所计算的Pitzer参数及文献测得的NaOH分解白钨矿的反应平衡浓度,用插值法计算了70℃下不同浓度NaOH(0.69~3.15 mol.L-1)分解白钨的热力学平衡常数(均为14.4×104-左右),证实计算所得Na2WO4和NaOH溶液的Pitzer参数是可信的。由此可见,利用Na2WO4和NaOH的Pitzer参数可对Na2WO4和NaOH溶液体系的热力学性质进行预测。     

含Mo低碳贝氏体钢动态再结晶研究

在Gleeble-1500热力模拟试验机上,测定变形量为60％,应变速率分别为0.1 s^-1,2.2s^-1,10s^-1,变形温度设置在1 100℃、1 050℃、1 000℃、960℃的含Mo低碳贝氏体钢的应力应变曲线.结果表明,钢在高温、低应变速率时,才有峰值应力出现,发生动态再结晶,在同一变形量下,相对于同一变形温度,变形速率越高,所对应的应力值越高.     

转炉留渣双渣工艺两阶段脱磷对比

 为了获得两阶段脱磷的关键工艺参数,通过统计100 t转炉留渣双渣工艺生产数据,比较了脱磷及脱碳阶段的脱磷有利条件,研究结果表明,两阶段脱磷条件对脱磷效果的影响规律存在显著差异,脱磷阶段炉渣碱度为1.8~2.2、Fe2O3质量分数为23%~28%、钢液温度为1 350~1 400 ℃时,可获得最优的脱磷效果;脱碳阶段炉渣碱度为3.2~5.2、Fe2O3质量分数为18%~30%、钢液温度为1 600~1 700 ℃时,提高炉渣碱度及Fe2O3质量分数或降低钢液温度可获得更优的脱磷效果;脱磷、脱碳阶段都没有达到热力学平衡,但脱磷阶段与热力学平衡差距更大,脱碳阶段更接近热力学上的平衡。     

Precipitation and Solid Solution of Titanium Carbonitride Inclusions in Hypereutectoid Tire Cord Steel

The properties of titanium carbonitride Ti(C_xN_(1-x))inclusions precipitated during solidification of tire cord steels and the thermodynamic conditions for their decomposition and solid solution during billet heating were investigated using a thermodynamics method.The solid solution of Ti(C_xN_(1-x))inclusions during high-temperature heating was also studied experimentally.The results revealed that:(1)the higher the content of carbon in the tire cord steel is,the greater the value of xin the Ti(C_xN_(1-x))inclusions is;(2)the higher the content of carbon in the tire cord steel is,the earlier the Ti(C_xN_(1-x))inclusions precipitated during the solidification process and the lower the solidification front temperature is during precipitation;(3)when an 82 Asteel sample was heated to 1 087℃,the Ti(C_xN_(1-x))inclusions possess the thermodynamic conditions of decomposition and solid solution;and(4)when 82 Asamples were heated to 1 150 and 1 250 ℃,the total number of Ti(C_xN_(1-x))inclusions larger than 5 μm in diameter decreased by55.0% and 70.3%,respectively.In addition,although smaller inclusions with diameter less than 2 μm continued to decompose when the sample was heated at 1 250℃for 2 hand then cooled to 1 000℃in the furnace,the number of inclusions larger than 5 μm in diameter increased.     

冷却速率对2507超级双相不锈钢σ相析出的影响

采用Gleeble 3500-GTC对Φ10 mm 2507超级双相不锈钢(/%:0.017C,6.22Ni, 25.73Cr, 3.39Mo, 0.27N)进行1340℃至室温以冷速1～500℃/min连续冷却实验,并通过EPMA(电子探针)、EBSD(电子背散射衍射)和热力学计算分析冷却速率对超级双相不锈钢σ相析出的影响。结果表明：2507超级双相不锈钢在1℃/min的冷却速率下,组织中存在σ相,σ相的面积百分比为2.67%。当冷却速率≥10℃/min,组织只有奥氏体和铁素体两相组成。热力学计算结果表明,冷却速率越小,σ相析出越容易。     

含钒铁水增碳与增碳剂的选择

通过分析含钒铁水增碳的热力学,证明了含钒铁水增碳的可行性。然后在1 500℃的增碳温度下,将5种增碳剂加入到含钒铁液,进行增碳试验。由试验结果可知,5种增碳剂的增碳效果优先顺序为:低氮增碳剂、石墨、无烟煤、碳粒、焦炭,增碳反应的平衡常数K的数量级为10~(-4)s~(-1)。分析认为,增碳效果的不同主要与增碳剂中硫含量和灰分含量的差别有关。综合分析表明无烟煤是含钒铁水增碳的最佳增碳剂,在实际生产中,吨铁加入13.2 kg无烟煤时,增碳量为0.5%。     

Precipitated phases of superaustenitic stainless steel 654SMO

The phase diagram of superaustenitic stainless steel 654SMO was calculated by thermodynamic software and the precipitated phases in the specimens aged at 800-1100°C for 1hwere studied by methods of physicochemical phase analysis,scanning electron microscopy and transmission electron microscopy.The results showed that the size of precipitated particles increased with increasing the temperature.The amount of second phases reached the maximum value at 900°C,but decreased above 900°C.There were about eight kinds of precipitated phases in 654SMO includingσphase,Cr_2N,μphase,χphase,Laves phase,M_(23)C_6,M_6C and M_3C,in which theσphase and Cr_2N were the dominant precipitated phases.     

调质渣的析晶行为

针对矿渣棉生产时调质渣成纤过程中会有晶体析出的问题,采用FactSage热力学软件、X射线衍射仪(XRD)和场发射扫描电子显微镜(SEM)研究调质渣不同温度下的矿物组成和显微结构;采用熔体物性综合测定仪研究调质渣降温过程中的黏度变化。结果表明,调质渣在冷却过程中,1 240 ℃时开始析出晶体,析出的主晶相为钙铝黄长石（Ca2Al2SiO7）和镁黄长石（Ca2MgSi2O7）。此外,熔融调质渣成纤适宜的温度区间为1 300～1 413 ℃。     

从不锈钢粉尘中选择性提取Cr、Ni和Zn重金属

基于热力学计算结果,通过配碳还原-熔分工艺,从不锈钢粉尘中选择性分步提取了Cr、Ni和Zn重金属元素.配碳还原实验结果表明,不锈钢粉尘的最佳配碳量为20%,粉尘中Fe、Ni和Zn的最低还原温度为1050℃,Cr的最低还原温度是1 400℃,与热力学计算结果一致,通过控制温度实现了对粉尘中金属的选择性分步还原.直接还原熔分实验说明,Fe-Cr合金最佳熔分温度为1550℃,粉尘中金属以Fe-Ni-Cr合金形式被提取出来,渣金分离状况良好,反应时间5min时金属提取率已达到75%左右,15 min时Fe和Cr收得率达到85%以上,Ni超过90%.通过控制配碳量、还原时间与反应温度,在不改变现有工艺的条件下,不锈钢粉尘直接返回炼钢主流程回收其重金属完全可行.      

BT25钛合金高温变形行为

对BT25钛合金在温度为950~1 100 ℃,应变速率为0.001~10 s-1条件下的高温变形行为进行了研究,分析了热力学参数对流变应力和微观组织的影响,并以Arrhenius方程为基础,构建了本构方程,最后进行了验证.结果表明:BT25合金在相同温度和应变速率下变形,变形量越大,动态再结晶越充分并细化了晶粒.相同变形量,变形温度越低,应变速率越高,动态再结晶晶粒尺寸越细小;流变应力随应变速率的增加而增加,随变形温度的升高而减小;BT25合金在α+β两相区（950~1 010 ℃）Q=763.51 kJ/mol,β相区（1 040~1 100 ℃）Q=231.36 kJ/mol.