加热温度对高硫车轮钢夹杂物化学冶金的影响

研究了高温加热对高硫车轮钢中MnS+Al2O3复合夹杂物结构与形态的影响。通过采用扫描电子显微(SEM)技术对高硫车轮钢中夹杂物的类型及尺寸进行了分析统计。结果表明：加热温度为1 300 ℃时,MnS回溶对MnS+Al2O3复合相的包裹效果没有产生显著地破坏作用。而当加热温度升至1 350 ℃后,由于大量的硫化物回溶,使不少氧化物夹杂物直接暴露于钢基体,破坏高硫钢中MnS＋Al2O3复合相的包裹效果。在含硫车轮钢的热加工过程中,应该尽量降低处理温度（低于1 300 ℃）来降低MnS回溶对全包裹Al2O3复合夹杂物的破坏作用。     

High-temperature corrosion of manganese in pure SO2

The corrosion of manganese in 1 atm of pure SO₂ has been studied from 700 to 900°C. The reaction shows two approximately parabolic stages, the first being faster; the reaction products are MnO and MnS. In the early moments of the reaction a fine mixture of oxide and sulfide is formed directly at the scale surface, which is not in equilibrium with the gas phase due to rate control by the surface reaction. This process ends quickly due to the lowering of the Mn activity at the scale surface, and then an outer region of MnO surmounting a dispersion of coarse MnS particles in the oxide develops. The rate control shifts to solid-state diffusion, and the scale surface equilibrates with the gas. The sulfide is produced in this stage in the interior of the scale as a consequence of sulfur penetration by two mechanisms whose relative importance is discussed. The reaction produces a protective scale, and the rate is close to that for oxidation of Mn in 1 atm O₂ at the same temperature.     

50W540型无取向硅钢的时效行为

研究了50W540型无取向硅钢中MnS粒子在300～700℃时效处理0.75～24 h不同时间时效析出行为与铁损变化的关系.结果表明,α-Fe基体中过饱和的Mn、S原子以MnS粒子形式沿位错析出,Mn原子的扩散距离是析出行为的制约因素.700℃时效时过饱和度低、Mn扩散快而MnS粒子易粗化,铁损降低.400～600℃时效时过饱和度高、MnS粒子析出数量增多,铁损升高.400℃以下时效时过饱和度很高,但Mn扩散慢,使细小MnS粒子难以析出且铁损无明显变化.     

常化温度对2.5%Si无取向硅钢第二相析出行为的影响

采用扫描电镜、透射电镜和双束扫描电镜对不同常化温度2.5%Si无取向硅钢中不同类型第二相析出物的析出行为和演化规律进行了研究。结果表明,常化温度从850℃升高至1100℃,微米级大尺度第二相粒子呈一次长大-析出-二次长大-回溶的变化规律;当常化温度<920℃时,析出相以AlN+MnS复合长大为主;随后小尺寸的MnS、AlN及其复合析出物数量迅速增多,并在950℃时达到峰值;随着常化温度的进一步升高,第二相粒子析出数量快速减少,然后缓慢增长至趋于平衡,大尺寸析出物出现部分回溶。纳米级析出物则以Cu₂S和Cu₂S+MnS复合析出为主。并且950℃常化时,2.5%Si无取向硅钢的铁损最低。     

含硫金刚石的合成及杂质分析

本文分别用Ni70Mn25Co5合金粉末和含添加剂硫的Ni70Mn25Co5合金粉末作触媒合成了金刚石单晶，通过对比，发现添加剂硫的引入使得金刚石内的包裹体含量增加，使晶体表面出现熔坑；利用X射线荧光光谱对晶体的杂质成分、相对含量进行了分析，发现杂质元素锰、硫的含量随着触媒中硫的添加量的增加呈增加趋势，由此推测在金刚石生长过程中生成了难熔的MnS，MnS以包裹体的形式进入金刚石中，在一定程度上破坏了金刚石的晶格排列，使得表面出现熔坑。     

取向电工钢中MnS析出粒子在冷变形过程中的行为

利用场发射扫描电子显微镜观察了试验材料Fe-3.12%Si-0.11%Mn-0.021%S中MnS析出粒子在变形量为0%～68%的冷压缩加工过程中的分布状态,统计了MnS粒子的总面密度及不同尺寸范围粒子的面密度,分析了冷压缩加工过程中MnS粒子的变化规律。结果表明,冷变形过程造成了几十纳米尺寸MnS粒子的碎化和10 nm以下粒子的少量回溶行为;但未能造成尺寸过于粗大粒子的细化。分析认为,MnS粒子与基体的界面能和塑性变形造成位错密度的明显升高构成了细小粒子回溶的驱动力。MnS粒子在冷轧过程中的细化,有利于防止初次再结晶晶粒粗化,促进取向电工钢二次再结晶过程的顺利进行及锋锐Goss织构的生成。     

硫对超高强度钢300M高周疲劳性能的影响

对高硫和低硫300M钢的显微组织和力学性能进行了系统研究,重点分析了硫含量对300M钢中夹杂物特征及高周疲劳寿命的影响机理。研究发现,硫含量的增加会大大降低300M钢的高周疲劳寿命。硫含量的增加会提高MnS夹杂物的析出温度及析出数量,提高试样次表层出现大尺寸MnS夹杂物的概率,大大降低高周疲劳裂纹萌生的难度,进而降低300M钢的高周疲劳寿命。     

EFFECT OF RARE EARTH ADDITIONS ON OVERHEATING OF Cr-Ni-Mo STEELS

本文研究了几种Cr-Ni-Mo钢的过热特征,提出把断口表面出现延性沿晶小平面作为过热的判据。在高的奥氏体化温度下,某种第二相粒子可以固溶,随后在冷却过程中沿高温奥氏体晶界重新析出,因而产生各种过热现象。MnS粒子的重新析出使普通硫含量的Cr-Ni-Mo钢发生沿晶延性破断,而AlN或VC粒子在高温奥氏体晶界的重新析出也能使低硫的Cr-Ni-Mo钢过热。稀土元素对几种Cr-Ni-Mo钢的过热都有抑制作用。当RE/S达到临界比值(约为4)时,不仅使MnS夹杂物完全转变成稀土硫化物和稀土硫氧化物,而且使高温奥氏体晶粒显著细化,改善韧性。如果RE/S比值远大于4,多余的稀土元素还可能与C,N原子发生交互作用。     

Effects of P+Cr complex modification and solidification conditions on microstmcture of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modif ier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic Al-Si alloys. The segregation of primary Si can be inhibited by adding a P+Cr complex modif ier and increasing the cooling rate during solidif ication. The ref inement of primary Si particles by P+Cr complex modif ication is due to the formation of CrS i2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrS i2 particles to the primary Si particles.     

The sulfidation of dilute Co-Cr alloys at low sulfur partial pressures(p_{{\text{S}}_{\text{2}} } = {\text{5x10}}^{{\text{ - 4}}} {\text{Torr)}}

The sulfidation of pure chromium and Co-Cr alloys containing 1, 5, 10, 17, and 25 wt. % Cr in H ₂-1%H₂S at 1000°C has been studied in detail by thermogravimetric methods, metallography, and electron probe microanalysis. In this gas mixture, which has an effective sulfur partial pressure of 5×10^–4 Torr, only CrS is formed, on all the alloys containing greater than 1 wt. % Cr, although there is some evidence that it may contain a little dissolved cobalt. The Co-1 Cr alloy is unattached. The sulfidation rate increases with increasing chromium content, the 25 wt. % Cr alloy corroding 100 times slower than pure chromium. Internal precipitation of CrS also occurs, the depth of the affected zone increasing with alloy chromium content. The rate-controlling mechanism appears to be the diffusion of chromium from the interior of the alloy to the alloy-scale interface, there being virtually no chromium remaining there. There is good qualitative agreement between the measured rate constants and values calculated from the rate of supply of chromium from the interior of the alloy.     

取向电工钢中MnS粒子析出形核行为

采用场发射扫描电子显微镜观察了取向电工钢中MnS粒子在热变形及不同温度保温后的析出形核行为。以经典的形核率理论为基础,确定了MnS粒子形核析出的更准确潜在位置密度,进而建立了改进的MnS析出形核模型。研究结果表明,MnS粒子主要在晶界和位错上形核,MnS在900℃析出时粒子密度最大。随热变形后保温温度的升高,位错密度及相应的MnS位错形核密度降低。理论计算与实验观察的结果符合良好。     

Ferrite nucleation potency of non-metallic inclusions in medium carbon steels

In recent years, there has been renewed interest in the role of non-metallic inclusions in controlling the microstructure of steels. The potency of various inclusions and precipitates such as SiO₂, MnO·SiO₂, MnS, Al₂O₃, Ti₂O₃ and VN for the nucleation of intragranular ferrite has been examined in the present study. Among them, single SiO₂, MnO·SiO₂, Al₂O₃, TiN and MnS particles seem to be inert to the nucleation of intragranular ferrite under the present experimental condition. Ti₂O₃ particles in a Mn-containing steel are very effective for the nucleation of intragranular ferrite, being (Ti,Mn)₂O₃ particles by absorbing Mn atoms from a steel matrix. On the other hand, Ti₂O₃ particles in a Mn-free steel are not effective. MnS and Al₂O₃ particles in high nitrogen steels containing vanadium also appear to be potent for the nucleation of intragranular ferrite. The decrease in transformation temperature causes a change in the morphology of intragranular ferrite from idiomorphic ferrite to acicular ferrite.     

M-EMS搅拌强度对钢轨钢MnS析出的影响研究

开展了M-EMS搅拌强度、硫质量分数对比工艺试验,采用Aspex分析了各工艺条件下钢轨特定位置MnS非金属夹杂的单颗粒长度尺寸及析出二维面积比例差异。结果表明：M-EMS搅拌强度越大,纯态较大尺寸的MnS非金属夹杂析出概率越大,复合态MnS非金属夹杂形核几率增加,同时也促进了较大尺寸的复合态MnS非金属夹杂形成;此外,硫质量分数较高的钢液更容易析出较大尺寸的纯态MnS非金属夹杂。降低钢液硫质量分数的基础上,增加形核质点并控制M-EMS搅拌强度可改善MnS非金属夹杂析出和分布。     

Effect of presulfidation on the oxidation behavior of co-based alloys. Part II. Presulfidation at sulfur partial pressures below the dissociation pressure of cobalt sulfide

A range of Co-Cr binary alloys, containing from 1 to 25 wt.% Cr, and Co-25 wt.% Cr-C alloys, containing 0.5, 1.0, and 2.0 wt.% C, have been oxidized at 1000°C after a preliminary sulfidation treatment under conditions where only chromium sulfide, CrS, was formed. Presulfidation has little significant effect on the subsequent overall oxidation rate, although it markedly increases the rate of deterioration of the alloy structure. The sulfur liberated by the oxidation does not escape to the atmosphere, but diffuses inward into the alloy, producing morphologies similar to those observed in hot corrosion and in laboratory tests involving molten sodium sulfate. The activity of sulfur beneath the oxide increases as the oxidation proceeds and, in some cases, becomes high enough to form liquid cobalt sulfides. This leads to an irregular oxidation front penetrating deeply into the alloy causing its fragmentation and incorporation into the oxide scale. This, too, is characteristic of hot corrosion behavior. From this it appears that the role of the sulfide may possibly have been underestimated in recent work and the importance of the molten salt chemistry overemphasized.     

2Cr13不锈钢小孔腐蚀敏感位置的研究

本文研究了2Cr13不锈钢小孔腐蚀敏感位置,试验证明:在NaCl介质中,2Cr13不锈钢蚀孔成核最敏感的位置是在包着Al_2O_3的复合硫化锰、钙夹杂物上。这种夹杂物被称之为“活性夹杂”。研究了合金元素S、Mn、Al(酸溶)和夹杂物Al_2O_3、MnS含量对耐蚀性的影响。当2Cr13不锈钢用铝脱氧时,钢中含有较多的此类“活性夹杂”,而且耐蚀性较低。但是,用Si-Fe脱氧时,钢中此类“活性夹杂”减少。2Cr13不锈钢耐蚀性明显提高。     

锆脱氧对船板EH36夹杂物和耐蚀性能的影响

为研究脱氧方式对船板夹杂物形态和耐蚀性能的影响,采用锆脱氧和铝脱氧,对比两种脱氧条件下钢板晶粒尺寸、夹杂物形态和耐腐蚀性能。结果表明,锆脱氧试验钢夹杂物主要为钙铝酸盐夹杂、球形复合氧化物;其中,大颗粒和长条状MnS夹杂物的密度较低,夹杂物弥散细小,可以阻止晶界迁移带来的晶粒长大,有效细化钢板晶粒尺寸。锆脱氧形成的钢中细小氧化物可以作为MnS异质形核核心,降低了钢基体MnS夹杂微区电化学腐蚀敏感性与扩展速度;这种复合氧化物电化学稳定性好,与铝脱氧方式相比,可以有效提升钢板耐蚀性能。     

S含量对高速车轮钢断裂韧性影响的研究

研究了S含量对高速车轮钢断裂韧性的影响.结果显示,适当提高车轮钢中的S含量,可以有效提高断裂韧性.对夹杂物的分析表明,S含量为0.001％(质量分数)的车轮钢中Al2O3和Al2O3+(Ca,Mg)O的氧化物夹杂相对较多,而MnS夹杂物较少.在相近的O含量水平下,将S含量从0.001％提高到0.006％,车轮钢中夹杂物...     

低碳低硫微合金化钢硫化物析出规律分析

利用热力学计算和Schiel凝固方程对于硫化物的析出进行计算模拟,最后利用金相组织证实MnS的析出规律.结果表明钢中MnS析出物是在钢凝固温度以下,锰及硫在晶界处偏析富集,[Mn][S]反应平衡发生移动而生成的.热力学计算和Schiel方程得出析出量随着温度的降低而逐渐增加.最后结合金相组织能谱,说明MnS,CaS共生出现,且温度降低MnS析出量增多.     

Corrosion of Inconel 690 in N<Subscript>2</Subscript>-0.1%H<Subscript>2</Subscript>S gas at 700-800 °C

Inconel 690 superalloy was corroded at 700 °C and 800 °C for up to 70 h in N₂-0.1% H₂S gas. It corroded almost linearly with large weight gains, displaying little protectiveness. Its corrosion rates were quite fast when compared with its corrosion in air or Ar-1%SO₂ gas. The formed scales were thick, fragile, and nonadherent. They consisted primarily of Cr₂O₃ with some NiCr₂O₄, Ni₃S₂, CrS, and Cr₂S₃. The H₂S gas accelerated the corrosion significantly by forming nonprotective sulfides and dissolving hydrogen in the scale and in the internal corrosion zone that consisted of discrete chromium-sulfides and some oxide particles. The marker test indicated that the scales grew by the outward diffusion of metallic ions such as Ni, Cr, Fe, and Mn, whilst the internal corrosion zone thickened by the inward migration of oxygen and sulfur through the lattice, grain boundaries, and microcracks.