钙处理对稀土在C-Mn钢中作用的影响

 为了明确钙处理对稀土在C-Mn钢中作用的影响,利用扫描电镜、光学显微镜和超景深三维显微镜对热轧态试验钢夹杂物和显微组织进行了观测,结合热力学计算和冲击断口分析结果,对比研究了稀土和钙-稀土复合处理对C-Mn钢力学性能的影响规律。结果表明,稀土能将钢中典型夹杂物改性为近球形的含硅稀土氧化物的复合夹杂,尺寸细化,长宽比降低。钙-稀土处理后夹杂物变为球形含稀土和钙的复合夹杂,钢洁净度增高;添加钙能将稀土的收得率从7.6%提高到42.4%,有效提高稀土利用率,钙-稀土处理后珠光体所占面积百分比提高,钢的强度提高。证明采用钙处理提高稀土在C-Mn钢中的作用是可行的。     

钙处理对稀土在大线能量焊接HAZ中作用的影响

 为了探明钙处理对稀土改善C-Mn钢焊接HAZ韧性作用的影响,利用Gleeble模拟了热输入为339 kJ/cm的焊接热循环过程,对比研究了稀土处理钢和Ca-稀土处理钢焊接HAZ中夹杂物、显微组织和低温冲击韧性差异,分析了钙对稀土在HAZ中作用的影响规律,发现钙处理能促进稀土改善HAZ低温冲击韧性。钙能使稀土处理钢HAZ中的夹杂物从稀土氧化物复合夹杂转变为稀土-Ca的复合夹杂,平均尺寸从1.5增大到2.2 μm,长宽比从1.5减小到1.4,夹杂物总量降低。虽然钙对稀土处理钢HAZ中晶内针状铁素体的含量影响不大,但钙能增强稀土对HAZ原奥氏体晶粒粗化的抑制作用,Ca-稀土处理钢HAZ原奥氏体晶粒尺寸比稀土处理钢小。热输入为339 kJ/cm时,钙处理能使稀土处理钢HAZ低温冲击韧性明显提高。     

易切削钢中Ca-Al-O-Mn-S系氧硫化物变性的热力学计算

本文对易切削钢中Ca-Al-O-Mn-S系氧硫化物变性进行了热力学计算。计算结果表明,硫含量愈高,氧硫化物变性所要求的Ca愈高而Al愈小。易切削钢中常见的是CA_6-(Mn,Ca)S和CA_2-(Mn,Ca)S。由于其较高的硫含量,液态CmA_n-(Mn,Ca)S不可能形成。实验结果同热力学计算相当吻合。     

3Cr2W8V热作模具钢的稀土合金处理

采用15tEAF冶炼,25tLF精炼,740kg铸锭锻制成Φ110mm的3Cr2W8V钢材。在LF精炼后期,钢中氧含量为29×10^-6,加入0.048%RE合金(%:21~24RE,44Si,3Mn,5Ca,3Ti,余Fe)进行稀土合金处理,稀土元素的回收率为30.78%。检验结果表明,进行稀土处理能够有效地改善3Cr2W8V模具钢共晶碳化物偏析,并显著减少P、Pb、Sn、As、Sb等有害元素在晶界的偏析。     

Behaviors of Lanthanum and Cerium on Grain Boundaries in Carbon Manganese Clean Steel

The behaviors of La and Ce on gram boundaries in carbon manganese clean steel were investigated by high-reso- lution transmission elecetron microscope （HRTEM）, scanning elecetron microscopy（SEM ）, energy dispersive spectrometer （EDS） and X-ray diffraction（XRD） analysis. The existing forms of rare earths （RE） in clean steel were as follows： dissolved in sohd solution, forming inclusion or second phase containing RE （RE-Fe-P, La-P, Fe-La eutectic and Fe-Ce phase）. The dissolved La or Ce segregated at grain boundaries. The segregation of both S and P at gram boundaries was reduced with suitable RE content. The impact toughness of the steel was improved obviously. La and Ce had effecets on purifying molten steel and modifying inclusions in clean steel, whereas with excessive La or Ce, La-Fe-P, La-P and Fe-La eutecetic phase or Ce-Fe-P and Fe-Ce intermetallic compound would form along grain boundaries, causing the impact energy to decrease significantly.     

热处理对高强度易切削沉淀硬化不锈钢2Cr16Ni3Mo2CuN力学性能的影响

高强度易切削沉淀硬化不锈钢2Cr16Ni3Mo2CuN在退火状态下有优良的切削性能。研究了经过一级退火温度710~800℃和二级退火温度570~620℃处理后2Cr16Ni3Mo2CuN钢的布氏硬度(HB)值,以及1 050~1 085℃45 min油冷,-70℃2 h,150,170℃回火后的力学性能。试验结果表明,710~740℃5 h空冷+620℃5 h空冷处理后,2Cr16Ni3Mo2CuN钢HB值在321以下;1 050~1 085℃淬火,150~200℃回火处理后,该钢强度极限σ_b≥1 520 MPa,δ₅≥12%,冲击功A_KU≥40 J。2Cr16Ni3Mo2CuN钢具有明显的二次硬化特征,二次硬化峰温度范围为480~520℃。     

易切削钢46S20轧制工艺及性能的研究

46S20易切削钢的轧制难题主要是轧制温度的制定，通过对轧制温度的控制，制定出4种不同的轧制工艺。轧制结果及性能分析表明，开轧温度控制在1100～1180℃范围内较好，高于此温度范围轧制时会出现轧件打滑，咬入困难现象，温度低于此范围，钢容易发生热脆，轧件头部易开裂。46S20易切削圆钢的显微组织主要是铁素体与珠光体。     

环保型含Bi低碳高硫易切削钢的开发

开发Bi易切削钢1215M(%:0.06C、0.04Si、1.25Mn、0.39S、0.17Bi)替代Pb易切削钢SUM24L。生产Bi易切削钢的流程为40t UHP EAF-40t LF(喂Bi线)-180 mm×180 mm连铸-连轧工艺。试验结果表明,Bi易切削钢1215MΦ9 mm盘条夹杂物分布均匀,Bi易切削钢1215M的切削性能优于SUM23HS含S易切削钢与SUM24L含Pb易切削钢相当。     

Effect of titanium and rare earth microalloying on microsegregation,eutectic carbides of M2 high speed steel during ESR process

The effects of RE and Ti microalloying during electroslag remelting(ESR) process on the microsegregation and morphology of eutectic M_2C carbides in M2 high speed steel were investigated.The results show that the addition of 0.2 wt% RE can alleviate the segregation of C,W,Mo,V and Cr,while the morphology of eutectic M_2C carbides hardly changes.The microalloying with the addition of 0.5 wt% Ti has the lowest degree of microsegregation due to the improvement of primary dendrites by the effective heterogeneous nucleating agent of(Ti,V)(C,N) particles.The addition of Ti makes the mo rphology of M_2C carbides change from rod-like or maze-like shape into a coarse feathery shape,exhibiting anisotropic facet growth characteristics.For the microalloying of 0.2 wt% RE and 0.5 wt% Ti,the segregation of the main metal alloying elements is slightly more severe than that of the addition of only RE or Ti.Under the combined action of RE and Ti,the feathery eutectic M_2C becomes thinner and shorter and tends to be isolated or distributed in a discontinuous network.     

Effect of rare earth addition on continuous heating transformation of a high speed steel for rolls

The effect of rare earth(RE) on continuous heating transformation of a high speed steel for rolls was investigated by using differ-ential scanning calorimetry(DSC) with combination of microstructure analysis.Determination of the Ac1 and Ac3,the starting temperature of carbide dissolution and melting upon heating,the enthalpy change for the α→γ transformation and overall carbide dissolution were also es-tablished.It was found that RE could reduce the volume fraction of large eutectic carbides and the chrysanthemum-like eutectic colonies but could not change the phase composition.RE made a little change to Ac1,but the variation in Ac3 and enthalpy for the α→γ followed an in-creasing pattern as the RE addition increased.The start temperatures of carbides dissolution increased with increase of RE addition,which may be associated with the influences of RE on the morphology of carbides,but the overall enthalpy change of carbides dissolution decreases as the RE addition increased.Moreover,the start temperature of melting also increased with increasing RE addition.     

碲系易切削钢及其切削性评价

硫系易切削钢利用硫化物的脆断性来提升钢材的切削性能,硫化物的形态、大小、分布是决定易切削钢切削性能优劣的关键因素.上海大学与芜湖新兴铸管有限责任公司合作,通过在1215MS易切削钢基础上添加碲元素,来改善硫化物的形态及分布,提升产品的切削性能.结果表明:硫系易切削钢添加质量分数0.016％ 的碲后,易切削钢中硫化物三维...     

聚焦离子束扫描电镜三维重构夹杂物的形态和分布

以MnS易切削钢和EH36电渣焊焊缝区样品为研究对象,首先利用聚焦离子束扫描电镜的自动系列切片和成像(Auto Slice & View)功能对夹杂物进行逐层切片并成像,然后利用Amira软件根据夹杂物的衬度进行三维重构,从而得到钢铁材料中单一夹杂物及复合夹杂物的形态和分布。其中,复合夹杂物的物相确定还结合了电子探针的元素面分析和电子背散射衍射的物相分析功能。结果表明,MnS易切削钢中的夹杂物呈现条形体、纺锤形体和椭球形体共存的分布状态,而EH36电渣焊焊缝区的复合夹杂物主要由晶态Mn₂TiO₄相和富集Al、Ca、Mg、Si、Mn、O元素的非晶相组成,且两种相伴生存在。夹杂物的三维重构图清晰显示了夹杂物的形态和分布特征,对于研究夹杂物对钢材性能的影响提供了重要依据。     

X射线荧光光谱法测定易切削不锈钢中铅碲铋

在圆珠笔笔头最顶端的地方,材料厚度仅有0.3~0.4mm,需要极高的加工精度,对不锈钢原材料(易切削钢)提出了极高的性能要求。易切削钢是指在钢中加入一定量的S、P、Pb、Te等易切削元素,以改善其切削性的合金钢,钢中微量元素的准确分析直接影响到该钢种的冶炼成功与否。研究发现桶样分析稳定性更优于球拍样,因此实验采用铣床对桶样进行制样,刀头旋转速度为300r/min、进刀速度为250mm/min。通过对X射线荧光光谱仪晶体、2θ角和脉冲高度等基本分析条件优化后,使用标样绘制了易切削不锈钢样品中Pb、Te、Bi的回归曲线,回归精度(SEE)分别为0.0034、0.0027、0.0046,实现了X射线荧光光谱法(XRF)对易切削不锈钢中Pb、Te、Bi含量的测定。Pb、Te、Bi的检出限分别为0.0009%、0.0012%、0.0006%。用实验方法测定生产样品(编号3125)中Pb、Te和Bi含量,测定结果的相对标准偏差(RSD,n=11)均不大于1.1%;对易切削钢生产样品进行正确度分析,分析结果与化学湿法、火花放电原子发射光谱法一致性较好。     

Effect of Rare Earth on Microstructures and Properties of High Speed Steel With High Carbon Content

The effects of rare earth （RE） on the microstructures and properties of high carbon high speed steel （HCHSS） were investigated. The results show that when suitable RE is added to the HCHSS, the effect of RE on the austenite and eutectic carbides is obvious. The austenite grain and coarse eutectic structure are refined, and flake carbides in the eutectic structures become short and fine. After heat treatment, most of the eutectic carbides are spheroidized and distributed in a uniform manner. The hardness and red hardness of modified HCHSS are slightly increased; impact toughness is greatly increased by 37.81% and reaches 10.17 J/cm^2. The mechanism by which RE improves the structures and properties of HCHSS is also analyzed.     

国内1215系低碳高硫易切削钢的工艺流程和内部质量控制

对国内100 t EAF-LF-CC和80 t、100 t、160 t转炉-LF-CC四条生产线生产的1215系低碳高硫易切削钢(/%:0.05～0.10C、≤0.013Si、1.06～1.33Mn、0.051～0.061P、0.24～0.36S、0.012 0～0.0140[O]、≤0.005Al)进行实物分析。结果表明,国内1215低碳高硫钢成分控制特点为通过适当提高Mn含量控制钢中的Mn/S (3.7～3.9),个别流程通过降低S含量可使Mn/S达4.4;160 t转炉流程在夹杂物控制上优于其余流程(Mn/S=3.8, MnS夹杂面积和长宽比波动较小)。.由于连铸坯元素偏析较小和轧后冷却速度控制得当,80 t转炉流程和160 t转炉流程生产的钢中无明显的带状组织,而100 t电弧炉流程和100 t转炉流程生产的钢中带状组织级别为3～4。     

Effect of RE on Granulation of Eutectic Carbide in Ledeburite Steel

ＲｅｃｅｎｔｌｙｔｈｅｂｅｎｅｆｉｃｉａｌａｃｔｉｏｎｓｏｆＲＥｏｎｉｒｏｎａｎｄｓｔｅｅｌｓｈａｖｅｂｅｅｎｒｅｐｏｒｔｅｄａｒｏｕｎｄｔｈｅｗｏｒｌｄ．ＲＥｃａｎｎｏｔｏｎｌｙｄｅｏｘｉｄｉｚｅａｎｄｄｅｓｕｌｐｈｕｒｉｚｅｔｈｅｍｅｌｔａｎｄｆ...     

稀土和镁对TiB2/A356复合材料微观组织的影响

采用混合盐反应法原位合成TiB2/A356复合材料,研究了Mg和RE元素对复合材料的微观组织的影响,并探讨了其作用机理.结果表明,在5％ TiB2/A356复合材料中加入1.5％ Mg时,TiB2颗粒尺寸得到细化且分布均匀.当Mg含量达到3％时,其对TiB2细化作用减弱.在联合添加Mg和RE元素时,能够进一步细化样品中的TiB2颗粒、α-Al和共晶Si相,且能使TiB2颗粒分布更加均匀.随着RE含量的增加细化效果更加明显.     

改质工艺对高强度低合金钢夹杂物特性的影响

利用300 t钢包炉工业试验研究了不同夹杂物改质工艺(包括未改质、稀土处理和钙处理)对铝镇静高强度低合金钢夹杂物特征的影响.结果表明,未改质处理炉次钢板中夹杂物为高铝含量的Al-M g-Ca-O-S-M n复合夹杂物,夹杂数量密度最小(仅为7.4和9.5个/mm2),但夹杂物平均尺寸大于3μm,在轧板中检测到不小于20...     

基于挥发影响的CaF2-Al2O3二元相图测定与解析

 为实现对CaF₂-Al₂O₃二元相图做出有效测定与评价,首先利用FactSage软件计算和熔点测试绘制了CaF₂-Al₂O₃二元相图,共晶点成分为10%Al₂O₃-90%CaF₂(质量分数),共晶温度为1 340 ℃。通过热重-差热试验发现,该二元体系升温过程存在明显失重和吸热,温度达到1 500 ℃时,90%CaF₂-10%Al₂O₃的试样失重率可达27%,失重主要是CaF₂挥发,并伴随明显吸热峰。基于失重及挥发反应,对熔点测定过程进行成分修正,得到新的CaF₂-Al₂O₃二元相图,共晶点成分为12%Al₂O₃-88%CaF₂(质量分数),共晶温度为1 340 ℃。最后,通过荧光分析对熔化后的渣样进行成分检测,结果与新的相图基本吻合。研究结果对含易挥发组元炉渣熔点测定及相图的绘制和解析具有参考价值。     

Fabrication and Luminescence Properties of Ca2Gd8(SiO4)6O2:Er3+ Phosphors via Sol-Gel Process

Ca2RE8(SiO4)6O2 (RE=Y, Gd, La) is a kind of ternary rare-earth-metal silicate with the oxyapatite structure, which was used as host materials for the luminescence of various rare earth and mercury-like ions. Ca2Gd8(SiO4)6O2:Er3 phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 ℃. SEM study reveals that the average grain size is 400～1000 nm. In Ca2Gd8(SiO4)6O2:Er3 phosphors, the Er3 shows its characteristic green emission at 528 nm (2H11/2-4I15/2) and 548 nm(4S3/2-4I15/2) upon excitation into 382 nm, with an optimum doping concentration of 5% (mole fraction) of Gd3 in the host lattices.