共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
3.
分析了南京钢铁公司100t高阻抗电弧炉→100t钢包精炼炉→150mm×150mm方坯连铸工艺流程生产GCr15轴承钢各阶段钢中氮含量的变化及其影响因素。实践表明,为降低轴承钢中氮含量,采取电炉兑入铁水量在55%以上和泡沫渣操作,EAF出钢时钢中氮的质量分数平均达到29×10-6;LF精炼采用大渣量埋弧操作、氩气搅拌,该过程平均增氮质量分数为21.8×10-6;VD吹氩过程平均脱氮量为15×10-6;全程保护浇铸有效控制平均增氮质量分数为6.3×10-6。LF精炼过程增氮对整个过程控制至关重要,应加强LF精炼的工艺优化。 相似文献
4.
5.
炼钢厂冶炼20CrMnTi,45,40Cr,GCr15钢的生产流程为70 t BOF-LF-VD-220 mm×220 mm CC工艺。由22炉20CrMnTi,40Cr和45钢中氮含量分析得出转炉出钢后钢中平均氮含量-[N]为21.70×10-6,LF精炼后平均[N]48.95×10-6,中间包平均[N]63.62×10-6。通过将铁水比从85%提高到92.3%,控制转炉终点[P]≤0.008%,出钢前钢包充氩,LF精炼快速形成泡沫渣,渣层厚100~120 mm,防止钢水吸氮,连铸时采用长水口控制吹氩量等措施,6炉GCr15钢冶炼结果表明,LF精炼后[N]为51.8×10-6~60.2×10-6,VD后[N]29.1×10-6~33.9×10-6,钢材中氮含量为31.8×10-6~40.0×10-6,满足用户对钢材冷加工的需要。 相似文献
6.
武钢第二炼钢厂使用RH-KTB设备主要生产w(C)很低(w(C)≤15×10-6)的冷轧薄板钢.为了同时把有害元素w(N)降至15×10-6以下,进行了125炉次的深脱氮工艺试验.试验结果表明,RH-KTB法可以同时深脱氮,平均初始w(N)为24×10-6,经过约25 min精炼,最终钢液中w(N)可以稳定控制在15×10-6以下,成功率达80%.同时发现,脱氮反应主要发生在吹氧快速脱碳阶段,脱氮随着脱碳速率增大而加快,6~8 min脱碳减弱后,靠提高真空度、增大吹氩量和循环量等措施,还能继续深脱氮,可以脱去脱氧合金化时合金带入的增氮量. 相似文献
7.
对涟钢CSP生产SPHC钢进行了w(N)、洁净度及成材夹杂物分布的分析研究,同时,对钢的组织结构作了简单的分析。研究结果显示:在目前生产条件下,LF处理过程中钢液吸氮量最大,达到16.01×10^-6,且波动幅度较大;在LF精炼过程中脱氧率比较高,达到53.6%,但在精炼处理后至铸坯阶段,钢中全氧质量分数有大幅度的升高;在各工序段中,LF精炼过程中夹杂物数量最少,精炼效果明显,但后续工艺需要加强;SPHC成材夹杂物粒径以小于10um的为主,占夹杂物总量的90%以上,形态以球形为主;从铸坯中大型夹杂的来源来看,结晶器保护渣是主要来源;SPHC钢的组织分析结果显示,钢基体为珠光体-铁素体组织。 相似文献
8.
9.
10.
11.
12.
通过对采用Si-Al-Ba-Ca合金进行脱氧实验研究分析,证实用用此合金脱氧可提高钢的纯净度,改善钢水流动性和提高高线盘条的质量。 相似文献
13.
在常压空气自蔓延高温合成锰锌铁氧体粉料研究中,采用XRD、SEM、VSM讨论了铁粉含量对燃烧反应、燃烧产物物相、形貌及磁性能的影响。结果表明:燃烧合成温度和燃烧合成的速度随着燃料铁粉含量k的增大而增大,在k=0.8时获得最大值而后有所下降。燃烧合成反应的激活能为22.74 kJ/mol和123.3 kJ/mol。当铁粉含量k=0.6时,可获得铁氧体化较完全的锰锌铁氧体料粉,其燃烧合成速度为1.93 mm/s,燃烧温度约1 593 K;其比饱和磁化强度为64.4 A.m2.kg-1,比剩磁强度为1.349 A.m2.kg-1,矫顽力为0.24 kA.m-1。该粉料平均粒径为1.42μm。 相似文献
14.
15.
用碳饱和法研究了1450℃时Mn-Fe-C系和Mn-V-C系有关的热力学性质,得到Mn-Fe-C系:Xc=0.27994-0.10044XFc,lnγc^0=-1.4558,εCC=9.896,εc^Fc=0.359,ρc^Fe=0.064,εc^F3=1.354,C的活度系数表达式为lnγC=-1.4558 9.896Xc 1.354XF3;Mn-V-C系:Xc=0.2771 0.3395Xv,εc^V=-1.225,ρc^V=0.751,εc^V=-4.584,C的活度系数表达式为lnγc=-1.4558 9.896Xc-4.584Xv. 相似文献
16.
高铬铸铁抗磨、耐热、耐蚀性能的研究 总被引:2,自引:0,他引:2
分析了高铬铸铁具有的抗磨、耐热、耐蚀性机理。通过对化学成分(碳、铬、和锰、钼、铜等合金元素及稀土元素)的含量在此3类铸铁中的影响研究,提出了相关设计参数。 相似文献
17.
18.
19.
20.
G Tian WJ Rocque JS Wiseman IZ Thompson WD Holmes PL Domanico JA Stafford PL Feldman MA Luther 《Canadian Metallurgical Quarterly》1998,37(19):6894-6904
Purified recombinant human type 4 phosphodiesterase B2B (HSPDE4B2B) exists in both a low- and a high-affinity state that bind (R)-rolipram with Kd's of ca. 500 and 1 nM, respectively [Rocque, W. J., Tian, G., Wiseman, J. S., Holmes, W. D., Thompson, I. Z., Willard, D. H., Patel, I. R., Wisely, G. B., Clay, W. C., Kadwell, S. H., Hoffman, C. R., and Luther, M. A. (1997) Biochemistry 36, 14250-14261]. Since the tissue distribution of the two isostates may be significantly different, development of inhibitors that effectively inhibit both forms may be advantageous pharmacologically. In this study, enzyme inhibition and binding of HSPDE4B2B by (R, R)-(+/-)-methyl 3-acetyl-4-[3-(cyclopentyloxy)-4-methoxyphenyl]-3-methyl-1-pyrrolidin ecarboxylate (1), a novel inhibitor of phosphodiesterase 4 (PDE 4), were investigated. Binding experiments demonstrated high-affinity binding of 1 to HSPDE4B2B with a stoichiometry of 1:1. Inhibition of PDE activity showed only a single transition with an observed Ki similar to the apparent Kd determined by the binding experiments. Deletional mutants of HSPDE4B2B, which have been shown to bind (R)-rolipram with low affinity, were shown to interact with 1 with high affinity, indistinguishable from the results obtained with the full-length enzyme. Bound 1 was completely displaced by (R)-rolipram, and the displacement showed a biphasic transition that resembles the biphasic inhibition of HSPDE4B2B by (R)-rolipram. Theoretical analysis of the two transitions exemplified in the interaction of (R)-rolipram with HSPDE4B2B indicated that the two isostates were nonexchangeable. Phosphorylation at serines 487 and 489 on HSPDE4B2B had no effect on the stoichiometry of binding, the affinity for binding, or the inhibition of the enzyme by 1. These data further illustrate the presence of two isostates in PDE 4 as shown previously for (R)-rolipram binding and inhibition. In contrast to (R)-rolipram, where only one of the two isostates of PDE 4 binds with high affinity, 1 is a potent, dual inhibitor of both of the isostates of PDE 4. Kinetic and thermodynamic models describing the interactions between the nonexchangeable isostates of PDE 4 and its ligands are discussed. 相似文献