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残余元素对涟钢CSP热冷轧卷质量的影响 总被引:1,自引:0,他引:1
钢中的残余元素问题是钢铁冶金面临的重要问题之一,高性能新钢种必须考虑残余元素的有害影响.涟钢矿石来源多而杂,导致铁水中As,Cu,Pb,Sn,Sb等残余元素增加.从残余元素(As,Cu,Pb,Sn,Sb等)对涟钢热轧卷、冷轧卷表面质量和力学性能的影响进行分析.分析结果表明:送检的热轧卷发现表面氧化铁与试样基体的界面有铜的富集;晶界处铜的富集会成为热轧卷产生裂纹的原因之一;冷轧卷酸洗后表面有黑点,黑点处发现有Cu,As,Sn,Sb等残余元素的富集;对特定时期的热轧卷力学性能进行多次逐步回归分析发现Sb对屈服强度有显著的负相关. 相似文献
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一、前言 普炭钢中有一定量的Cu、As、Sb、Sn残余元素时,在热加工过程中,常引起钢的热脆,它多产生于轧制头几道次和不均匀变形严重道次。龟裂在刚产生初期,只是横向裂纹,继继轧制,随轧件的延伸及金属的流动,裂纹变宽。金相检验及夹杂物分析表明,尽管龟裂严重,钢的组织却是正常,并无过烧现象,龟裂与夹杂物亦无对应关系,生产和试验分析表明:钢材上的这种缺陷,主要是钢中Cu、As、Sb、Sn元素含量较高并在高温下选择性氧化而引起表面富 相似文献
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研究了电弧炉+AOD和转炉+VOD冶炼的奥氏体不锈钢SUS304HC(%:≤0.06C、18~19Cr、8~11Ni、2~3Cu)和201Cu(%≤0.08C、7.5~10.0Mn、14~17Cr、4~6Ni、2~3Cu)中Sn、Pb等残余元素含量对初轧坯角裂和环向裂纹以及盘条表面横向裂纹的影响,并分析了残余元素的来源和控制措施。结果表明,当钢中Pb含量超过0.001%或Sn含量超过0.011%时,不锈钢热塑性降低,轧坯角裂倾向增加;控制炉料中残余元素含量是降低钢中Pb、Sn含量,提高初轧坯表面质量的有效措施。 相似文献
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三钢高线厂基于连铸坯直接辊道热送热装生产的SWRCH22A盘条1/4冷顶锻的开裂率较高,其综合优质率只有63%.通过对裂纹形貌、显微组织和微区成分的分析发现顶锻开裂的原因在于钢中Cu、As、Sn元素在原奥氏体晶界处的偏聚以及热装组织处于铁素体和奥氏体两相区导致.多次生产实践表明通过控制有害微量元素和降低热装温度显著抑制了1/4冷顶锻裂纹的出现,产品合格率达到95%以上. 相似文献
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本试验以热弯曲为变形方式,在实验室条件下研究了钢3中的Cu、Sn残余元素含量、加热温度、加热时间与“表面热脆”的关系。并通过工业性试验初步验证了实验室试验结果。试验表明,含Cu、Sn普碳钢影响“表面热脆”的主要因素是“加热温度”。Cu、Sn残余元素含量较高的普碳钢采用“高温轧制”工艺可避免轧材产生“表面热脆”。 相似文献
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《钢铁研究学报(英文版)》2015,(7)
The effect of tramp elements in the steel was intensively studied.It was found that the solubility of tramp elements decreased as the temperature decreased under normal cooling conditions.The tramp elements(Cu,Pb,and Sn)diffused toward the grain boundaries,and intermetallic compounds or rich phases which have low melting points were formed,causing reduction in ductility and failure during the bending test.Rebars with Cu content which were left to air cooling after the last step showed drop in elongation,up to 32%.On contrast,the samples with high percentage of tramp elements(Cu,Pb,and Sn)in the billet,which were rolled and subjected to Tempcore process,did not show drop in elongation or failure in bending test(especially for rebar with diameter less than 32mm);however,copper must be less than 0.35mass%to prevent the precipitation of Cu-rich zones of critical size in 32 mm.When quenching was applied,the tramp elements remained in the interstitial supersaturated solid solution positions inside the grains and would not have the chance to diffuse and form precipitates,hindering the copper precipitates from reaching the critical size necessary for impairing the properties.This would hinder the occurrence of the harmful effect of the tramp elements on the elongation or the hot shortness after rolling. 相似文献
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In view of the importance of tramp element contamination of steel products through a large volume of scrap consumption in the near future, the thermodynamic behaviour of Sb, As, Sn and Cu in CaO—CaF2 melts under reducing conditions was studied by examining the dependences of distribution of each element between Cu, Ag or Sn alloys and CaO—CaF2 melts on the CaO activity, oxygen partial pressure and temperature around 1 500°C. As a result, the reaction products on treatment by Ca compounds were demonstrated to be Ca3Sb2, Ca3As2, Ca2Sn and CaCu. Experimentally obtained distributions were extrapolated to lower oxygen partial pressures less than 10?18 atm to estimate the feasibility of removing those tramp elements from molten iron. It is thermodynamically indicated that if the prevailing oxygen partial pressure of the environment is below 10?23 atm, these impurities, except Cu, would be substantially removed from molten steel. 相似文献
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通过构建ND钢连铸坯凝固两相区内溶质的微观偏析模型, 不仅研究了C、S和P元素对固液两相区内钢的高温力学参数以及溶质再分配的影响, 还对P元素偏析比随冷却速率(CR) 的变化规律进行了探究.通过分析模型结果表明: 初始C的质量分数在0.075%~0.125%之间时, 随着初始C含量的增加, P、S元素的偏析加剧, 凝固末端温度下降幅度变大, 导致脆性温度区间增大; 增加P和S元素的初始含量, P、S元素的偏析比降低, 但会加剧其在枝晶间残余液相中的富集, 直接导致零塑性温度(ZDT) 下降; ND钢中的Cu含量低于显著提高裂纹敏感性的临界含量, 且凝固过程中Cu元素的偏析比较低, 因此在ND钢凝固过程中Cu元素不能主导裂纹的诱发; 在一定的冷却速率波动范围内, P元素的偏析比随着冷却速率(CR)的提高略有下降. 相似文献
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Hans Jürgen Grabke 《国际钢铁研究》1987,58(10):477-482
In steels produced and utilized in the Fed. Rep. of Germany the elements P and Sn may occur as impurities. Both these elements tend to enrich (segregate) at grain boundaries. The equilibria of grain boundary segregation in iron and the effects of alloying elements have been studied for P and Sn by Auger-electron-spectroscopy and were thermodynamically described. For a 3.5% NiCrMoV-turbine steel the grain boundary segregation of P and its effect on ductility have been studied in detail, with the results that the long-term embrittlement of this steel during application at temperatures around 400°C can be predicted and the maximum bulk concentration of P can be given. The effect of Sn on the creep of a 1% CrMoNiV steel at 550°C has been investigated, Sn favours cavity nucleation and growth, therefore tertiary creep starts earlier and premature failure occurs with increasing Sn content. Therefore, the Sn content should be kept as low as possible in heat resistant steels. Since carbon also segregates to grain boundaries and can displace P and Sn if there is enough free C in a steel, plain carbon steels are not subjected to embrittlement by P and Sn. The susceptibility to intergranular stress corrosion cracking in nitrates and other electrolytes is somewhat enhanced by P, however, only in a restricted range of potentials. In the range of maximum susceptibility the impurities have no effect, all carbon steels are susceptible to IGSCC, independently of their purity. So stress corrosion cracking cannot be suppressed by diminishing the content of phosphorus – only by avoiding the critical corrosion conditions concerning electrolyte and potential. 相似文献
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根据GB/15000《标准样品工作导则》、YB/T082-1996《冶金产品分析用标准样品技术规范 》和相关ISO导则研制了包含C、Si、Mn、P、S、Ni、Cr、Cu、Mo、V、Co、Sn、As、W、Nb、N 共16个元素的马氏体沉淀硬化型不锈钢S17400(17-4PH),双相不锈钢S32205、S32750和200系奥氏体不锈钢S20100(201)等4种典型低镍不锈钢光谱分析用标准样品。采用500 kg中频感应炉冶炼,冶炼过程利用感应磁力搅拌,301铝丝和硅-钙粉脱氧,小截面(145 mm)锭型金属模上注法浇铸,从而保证了钢液成分均匀、良好的脱氧效果和元素的较高回收率,避免了成分偏析和夹杂物的形成。铸锭经锻造和热轧后进行偏析和金相组织检验,结果表明被测元素没有偏析且组织结构能满足制作光谱标样的要求。用F方差法检验均匀性,各元素F值均小于临界值F0,表明被检元素的均匀性良好。由8家有资质的实验室采用多种不同原理,准确、可靠的分析方法协作定值分析,对分析结果进行统计和处理,得到了被定值元素的认定值和扩展不确定度。 相似文献
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Scrap-based electric arc furnace (EAF) steelmaking is limited by a surface cracking problem in the recycled steel products,
which is known as surface hot shortness. This problem originates from the excessive amount of copper (Cu) in the steel scrap, which enriches during the oxidation
of iron (Fe) and consequently melts and penetrates into the austenite grain boundaries. In this article, the effects of arsenic
(As), antimony (Sb), and tin (Sn) on surface hot shortness were investigated. A series of Fe-0.3 wt pct Cu-x wt pct (As, Sb, or Sn) alloys with x content ranging from 0.06 to 0.10 wt pct was oxidized in air at 1423 K (1150 °C) for 60, 300, and 600 seconds inside the
chamber of a thermogravimety analyzer (TGA) where heat is supplied through infrared radiation. Scanning electron microscopy
(SEM) investigations show that (1) the presence of Sb and Sn results in severe grain boundary cracking, whereas the presence
of As does not, (2) open cracks with Fe oxides were found beneath the oxide/metal interface in the Sb and Sn alloys, and (3)
the oxide/metal interfaces for all As, Sb, and Sn alloys are planar. Penetration experiments of pure Cu and Cu-30 wt pct Sn
liquid were also conducted in the chamber of a hot-stage confocal laser scanning microscopy (CLSM) in nonoxidizing atmosphere:
(1) on the Fe-35 wt pct manganese (Mn) alloys to study the correlation between cracking and grain boundary characters, and
(2) on the pure Fe substrates to exclude the bulk segregation effects of Sn on grain boundary cracking. It was found that
grain boundary cracking rarely took place on low-energy grain boundaries. The results also suggest that the bulk segregation
of Sn in the substrate is not necessary to promote significant grain boundary cracking, and as long as the liquid phase contains
Sn, it will be highly embrittling. 相似文献
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Since the interest in removing tramp elements from steels is increasing, one of the authors has reported the thermodynamic behaviour of P, Sn, As, Sb, Bi, Pb and Cu in CaO–CaF2 melts under strongly reducing conditions. In this investigation, the BaO–BaF2 system, which is more basic than the CaO–CaF2 system, was chosen as a flux and the thermodynamic behaviour of As and Sb in BaO–BaF2 melts was studied at 1300°C under reducing conditions. The partition ratios of arsenic between Cu–As and BaO–BaF2 melts and of antimony between Ag–Sb and BaO–BaF2 melts were measured as functions of the flux composition and the partial pressure of oxygen. Both partition ratios increase with an increase in the BaO content of the flux and with a decrease in the partial pressure of oxygen. The reactions for the removal of arsenic and antimony have been identified. The partition ratios of arsenic and antimony between carbon saturated iron and BaO–BaF2 melts are estimated and the possibility of the removal of tramp elements from molten iron by using a BaO–BaF2 flux is discussed. 相似文献
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F. Fattorini U. Franzoni S. Sturlese 《Metallurgical and Materials Transactions A》1990,21(7):1941-1949
The effect of impurity content on creep crack growth (CCG) rate and, more generally, on hot ductility of a typical lCrlMo0.25V
ferritic steel was evaluated. Four heats intentionally doped with various amounts of impurities were characterized after heat
treatments simulating the industrial thermal cycle taking place in a 1000-mm-diameter high-pressure rotor at two positions:
near the outside surface and at the center in the cases of air cooling and oil quenching, respectively. Results indicate that
the highest crack growth rates occur in the grade with a low P content (40 ppm) and Sn and Sb values (100 to 200 ppm) comparable
with those characteristic of commercial steels. A marked reduction in brittleness is achieved only through a substantial reduction
in the amount of Sn and Sb, even when medium-to-high P levels (100 ppm) are present. Creep resistance in terms of both time
to rupture and minimum growth rate is not influenced by the impurity content, at least within the range of stresses investigated.
Auger analyses on crept specimens demonstrate the presence of a selective segregation of impurity elements similar to that
found in other ferritic steels: P is the only segregating element at non-cavitated grain boundaries, while cavitated areas
contain Sn, Sb, and Cu in addition to P. The embrittlement at high Sn and Sb levels depends on two factors: at low P levels,
cracks rapidly propagate under surface diffusivity control; at high P levels, excess P segregates at the grain boundaries,
and crack propagation proceeds by an intergranular decohesion mechanism. 相似文献