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钒、氮微合金化钢筋的强化机制 总被引:15,自引:1,他引:14
研究了钒、氮微合金化钢筋的强化机理。研究结果表明 ,对 0 .11% V - 85× 10 - 6 N的低氮钢 (钒钢 ) ,约 35 .5 %的钒以 V (C,N)形式析出 ,5 6 .4%的钒固溶在基体中。而在 0 .12 % V- 180× 10 - 6 N的高氮钢中 (钒 -氮钢 ) ,V (C,N)析出量成倍增加 ,约 70 %的钒以 V (C,N)形式析出 ,只有 2 0 %的钒固溶于基体。增氮后 ,V (C,N)析出相的平均尺寸由 10 7nm减小至 73.7nm ,且 1~ 10 nm细小质点的质量比由 2 1.1%提高到 32 .2 %。钢中增氮还细化铁素体晶粒尺寸 相似文献
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低碳钒氮微合金钢中V(C,N)在奥氏体中的析出动力学 总被引:8,自引:1,他引:7
控制VN在奥氏体中的有效析出是利用VN诱导晶内铁素体细化铁素体晶粒的关键技术。采用应力松弛方法研究了低碳钒氮微合金钢中V(C,N)在奥氏体区的等温析出行为。结果表明:试验钢的析出-温度-时间曲线(PTT)呈典型的C形,本试验条件下析出开始时间最短的“鼻子”温度为870℃左右。钢中的碳、氮含量以及变形量对PTT曲线有较大影响,它们增加均使C曲线向左移,特别是氮含量对V(C,N)析出的影响最显著。在碳含量约为0.10%的试验钢中,当氮含量从0.0036%增加到0.0140%时,可使870℃的析出开始时间从400s缩短到70s左右。 相似文献
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控制VN在奥氏体中的有效析出是利用VN诱导晶内铁素体细化铁素体晶粒的关键技术。本文采用应力松弛法研究了低碳钒氮微合金钢V(C,N)在奥氏体区的等温析出行为,结果表明,试验钢的析出-温度-时间(PTT)曲线呈典型的“C”形状,本实验条件下析出开始时间最短的“鼻子”温度为870℃左右。增加钢中的碳、氮含量以及形变量等对PTT曲线有较大影响,均使“C”曲线向短时间方向移动,特别是氮含量对V(C,N)析出的影响最显著。V的高温析出促进了铁素体形核,产生了明显的晶粒细化效果。 相似文献
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X30N高氮不锈轴承钢在经过热处理后,材料表面会出现脱碳脱氮层,为研究C、N等局部成分变化对材料中第二相析出的影响,采用10 g/L氯化锂-40 g/L磺基水杨酸-5%(V/V)甘油甲醇溶液,通过电解萃取的方法将析出相从基体中分离,并利用X射线衍射仪(XRD)和扫描电镜(SEM)研究了析出相的结构和形貌,用碳硫分析仪、定氮仪和电感耦合等离子体原子发射光谱(ICP-AES)研究了析出相的元素含量。研究结果表明:经过热处理后,试验钢中主要析出相的类型为M23C6和Cr2(C,N),脱碳表面以Cr2(C,N)为主,随着距离脱碳表面深度的增加,M23C6的衍射谱峰逐渐明显,总析出相的含量逐渐增加,在脱碳表面下0.4 mm时基本达到稳定,C元素含量较脱碳层表面增加了460%,N元素含量较脱碳层表面增加了38.9%,总析出相元素含量较脱碳层表面增加了85.2%。Cr2(C,N)的形貌为球状颗粒,M23C6 相似文献
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结合JmatPro热力学软件对Nb-Ti-V-Mo微合金化E460海工钢中多元复合析出相的固溶热力学计算和经典形核长大动力学理论,研究了(Nb,Ti,Mo,V)C在奥氏体和铁素体中沉淀析出规律,探讨了奥氏体形变储能和形变诱导析出量对(Nb,Ti,Mo,V)C沉淀析出动力学的影响。研究表明,(Nb,Ti,Mo,V)C在1 448.6 K时开始析出。在奥氏体相区,随着温度的降低,临界形核功逐渐降低,NrT曲线和PTT曲线呈单调变化趋势。在奥氏体和铁素体两相区,(Nb,Ti,Mo,V)C的最快沉淀析出温度为1 062.6 K。随着形变储能的增加,相对形核率呈增加趋势,析出孕育期缩短。随形变诱导析出量增加,PTT曲线向左移动,最大形核率温度和最快析出温度为1 058.3~1 063.8 K。 相似文献
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《钢铁钒钛》2020,(4)
为了明晰X80管线钢凝固过程中析出物粒子析出规律。采用Thermo-calc软件对X80管线钢凝固过程中奥氏体、铁素体相转变温度,析出物类型,析出物开始析出温度与析出相最大质量分数进行热力学分析。计算结果表明:X80管线钢凝固过程析出相主要包括MnS相、AlN相、铁素体相及奥氏体相、富钛相碳氮析出相、富铌相碳氮析出相与碳化钒析出相。富钛相碳氮析出相析出温度为1 390℃,质量分数为1.2×10~(-4),析出相随C元素和Nb元素的含量增加而受到抑制。N元素和Ti元素含量增加会促进富钛相碳氮析出相生成,V元素质量分数增量对富钛相碳氮化物无明显规律。富铌相碳氮析出相在1 110℃析出,质量分数为1.3×10~(-3),随C元素和Nb元素的含量增加,促进富铌相碳氮析出相析出。增加N元素与Ti元素含量抑制富铌相碳氮析出相析出,V元素对富铌相碳氮化物无明显影响规律。碳化钒析出相析出温度为596℃,析出相质量分数为4.59×10~(-5),增加C元素和V元素含量利于碳化钒相析出,Nb元素含量增加对碳化钒相起到一定抑制作用。 相似文献
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R Escribano D Bermejo JL Calvente P Cancio AG Maki 《Canadian Metallurgical Quarterly》1999,193(1):174-182
BACKGROUND: The authors examined the interaction of ketamine with recombinant mu, kappa, and delta opioid receptors and recombinant orphan opioid receptors expressed in Chinese hamster ovary cells (CHO-mu, CHO-kappa, CHO-delta, and CHO(ORL1), respectively). METHODS: CHO-mu, CHO-kappa, and CHO-delta membranes were incubated with the opioid receptor radioligand [3H]diprenorphine at room temperature. Ketamine (racemic, R(-) and S(+)) was included at concentrations covering the clinical range. CHO(ORL1) membranes were incubated with [125I]Tyr(14)nociceptin and racemic ketamine at room temperature. The effects of racemic ketamine and selective opioid receptor agonists (mu: [D-Ala2, MePhe4, Gly(ol)5] enkephalin (DAMGO); kappa: spiradoline or delta: [D-pen2, D-pen5] enkephalin (DPDPE)) on forskolin-stimulated cyclic adenosine monophosphate formation also were examined. Data are mean +/- SEM. RESULTS: Racemic ketamine increased the radioligand equilibrium dissociation constant for [3H]diprenorphine from 85+/-5 to 273+/-11, 91+/-6 to 154+/-16, and 372+/-15 to 855+/-42 pM in CHO-mu, CHO-kappa, and CHO-delta, respectively. The concentration of radioligand bound at saturation was unaffected. In CHO-mu and CHO-kappa cells, racemic ketamine did not slow the rate of naloxone-induced [3H]diprenorphine dissociation. Ketamine and its isomers also displaced [3H]diprenorphine binding to mu, kappa, and delta receptors in a dose-dependent manner, with pKi values for racemic ketamine of 4.38+/-0.02, 4.55+/-0.04, and 3.57+/-0.02, respectively. S(+)-ketamine was two to three times more potent than R(-)-ketamine at mu and kappa receptors. Racemic ketamine displaced [125I]Tyr(14)nociceptin with an estimated affinity constant of 0.5 mM. Racemic ketamine inhibited the formation of cyclic adenosine monophosphate (naloxone insensitive) in a dose-dependent manner (concentration producing 50% inhibition approximately 2 mM) in all cell lines, including untransfected CHO cells. Ketamine (100 microM) reversed DAMGO (mu) and spiradoline (kappa) inhibition of formation of cyclic adenosine monophosphate. CONCLUSIONS: Ketamine interacts stereoselectively with recombinant mu and kappa opioid receptors. 相似文献
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稀土对低温固体B-C-N共渗的影响 总被引:3,自引:0,他引:3
本文研究了硼-碳-氮-稀土(B-C-N-RE)共渗工艺及共渗层的组织性能,并与硼-碳-氮(B-C-N)共渗工艺及共渗层的组织性能进行了比较,结果表明,在适当范围内,稀土具有明显的催渗作用;与B-C-N共渗相比,B-C-N-RE共渗层的耐磨性和耐蚀性明显提高。本文对B-C-N-RE共渗的机理及稀土元素的作用作了初步的探讨。 相似文献
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M. Djahazi X. L. He J. J. Jonas W. P. Sun 《Metallurgical and Materials Transactions A》1992,23(8):2111-2120
The influence of boron addition, amount of deformation, and solution heat-treatment temperature on the precipitation and recrystallization
behaviors of a family of high-strength low-alloy (HSLA) steels was studied. A stress relaxation technique was employed to
detect the occurrence of austenite recrystallization and to determine the precipitation start(P
s) and finish(P
f) times. After preheating to 1100 °C or 1200 °C for 30 minutes, the specimens were cooled to test temperatures between 800
°C and 1000 °C. They were subsequently deformed to true strains of 5 or 25 pct and subjected to stress relaxation. The advent
of recrystallization produced a sharp increase in relaxation rate, while the occurrence of carbonitride precipitation led
to the appear- ance of a stress plateau. The results indicate that the presence of boron (1) accelerates carbo- nitride precipitation
and (2) retards austenite recrystallization when present in combination with Nb. The precipitation-time-temperature (PTT)
diagrams determined in this investigation are C-shaped for both the B-free as well as the B-modified Nb steels. These data
were analyzed in terms of the classical theory of nucleation, on the basis of which it is demonstrated that the acceleration
of the nucleation kinetics of precipitation can be attributed to the segregation of boron and of boron-vacancy complexes to
dislocations and grain boundaries, as well as to the faster diffusion of Nb in the presence of boron. 相似文献