稀土复合变质对新型铸造热锻模具钢组织与性能的影响

研究了稀土复合变质对新型铸造热锻模具钢（CHD钢）组织与性能的组织。结果表明，稀土复合变质能细化晶粒，并且随着稀土量的增加。细化效果明显；加入适量的稀土复合变质后，夹杂物数量明显减少，夹杂物趋于球化并均匀地分布在钢中，形态和分布得以了改善，向钢中加入稀土进行复合变质，能促进贝氏体、奥氏体和位错亚结构的形成，细化马氏体板条。当残留稀土含量为0.02%时，CHD钢的硬度、强度变化不大，断裂韧性（KIC）和疲劳裂纹扩展门槛值（△Kth）有所提高，冲击韧性、延伸率、断面收缩率提高了近一倍，抗热疲劳性能也最好。     

稀土对中碳中合金ZG70Cr2MnNiSi钢组织和性能的影响

中碳中合金钢是近年发展起来的一种新型耐磨材料,可通过微合金化和变质处理来提高该钢种的强韧性。本研究以ZG70Cr2MnNiSi钢为研究对象,选用了两种稀土复合变质剂对其进行变质处理,测试并比较了不同变质剂处理后钢的力学性能和磨损性能,分析了钢的XRD物相图谱、金相组织、断口形貌和TEM微观组织,研究结果表明:变质处理有利于马氏体高密度位错的形成,促进了组织细化和碳化物的弥散析出,从而提高了铸钢的综合力学性能。     

铈在低硫铌钛钢中的微合金化作用

在实验室条件下采用50 kg真空感应炉冶炼和两段控制轧制工艺, 采用THERMECMASTOR-Z热模拟机对过冷奥氏体连续冷却转变曲线进行了测定, 试验结果表明, 低硫铌钛钢中稀土铈能提高钢的临界点tAr3和tAr1, 并且使(tAr3-tAr1)温度区间增大; 并使钢的CCT曲线右移和上移, 降低了钢的淬透性; 铈会使贝氏体转变点升高, 同时加大了贝氏体转变间隔; 当冷却速度较高时, 稀土使马氏体由粗条状变为细条状, 降低了Ms点, 并且增强了马氏体结构的板条化趋势, 抑制了片状晶生成.     

稀土在石油套管钢中的应用研究

稀土在Ｊ－５５钢级套管钢中有净化钢液，变质夹杂和微合金化作用，提高了钢的横向冲击值和抗裂纹扩展能力，显著改善了抗射孔开裂性能。稀土变质ＭｎＳ和Ａｌ２Ｏ３夹杂的程度，分别取决于钢中稀土与锰和稀土与铝的活度比值，而活度比值决定了钢中ＲＥＡｌＯ３和ＲＥ２Ｏ２Ｓ的相对数量和性能。     

稀土元素在新一代高强韧钢中的作用和应用前景

综述了稀土在钢中的应用和主要作用, 并从稀土的特性分析讨论了稀土在钢中的作用机制, 阐明稀土是钢的一种有效的强净化和变质剂, 固溶稀土的存在强烈影响微结构. 通过强净化、变质和微量合金化, 稀土可有效控制局域弱化, 降低微结构的能态, 有效抑制钢中有害元素和脆性相偏聚所造成的脆性断裂, 稀土可望作为发展21世纪高强韧钢、提高高强钢韧性的重要元素.     

镧对4Cr13钢组织及耐蚀性的影响

以含不同量稀土元素La的4Cr13马氏体不锈钢为研究对象,实验用钢经冶炼、锻造、热处理后,通过观察不同稀土含量的研究试样在光学显微镜下的组织,测试研究试样在模拟溶液中的自腐蚀电位,并使用交流阻抗法测试研究试样的交流阻抗谱,从而研究La对4Cr13马氏体不锈钢的组织及耐蚀性的影响.分析得出:在一定范围内,随着La加入量的增加,其耐腐蚀性增强,La加入4Cr13马氏体不锈钢中能够细化晶粒,改变碳化物形态,减少碳化物偏聚,提高钢的强度、塑性和耐腐蚀性.     

连铸BNbRE重轨钢中稀土对夹杂物的作用

论述了稀土在钢轨中的作用,得出采用模铸方法生产的稀土轨(BNbRE)中稀土具有净化钢液、变质夹杂和微合金化作用.稀土轨采用连铸生产后,钢中硫、氧含量有大幅度的降低,钢水质量提高.在相同稀土加入量的条件下,虽然钢中残留稀土含量降低,同样取得了稀土钢轨综合性能,但稀土在钢中的净化和夹杂物变质作用有变化,对硫、氧夹杂物的作用不明显.     

碳锰洁净钢中镧和铈在晶界的行为

应用高分辨TEM，SEM和XRD研究碳锰洁净钢中镧和铈的存在形式、分布以及在晶界的行为。研究结果表明，镧和铈在洁净钢中存在固溶态、稀土夹杂物和稀土第二相。固溶稀土偏析在晶界，洁净钢中稀土仍有净化钢液和变质夹杂的作用。适量稀土能减少S和P在晶界的偏析，净化晶界提高钢的冲击韧性。过量稀土在晶界产生有害的稀土第二相，导致性能显著降低。     

稀土对20Mn钢等温相变及组织形态的影响

研究了不同稀土含量对20Mn钢等温相变及组织形态的影响。随钢中稀土含量的增加,先共析铁素体析出的孕育期缩短,完成珠光体相变所需时间延长;针状铁素体量减少直至消失;珠光体片间距变密且相对转变量减少;粒状贝氏体中碳化物易于偏聚。稀土减小原奥氏体晶界能和相界面能,稀土原子偏聚在相界面上阻碍碳原子的扩散,以及可能形成高熔点稀土碳化物而减少奥氏体中碳的固溶量,是产生上述结果的主要原因。     

稀土变质钒白口铸铁的研究

采用稀土单元变质剂和稀土－硅复合变变质剂对钒白口铁（１．８０－２．１０％）Ｖ进行变质处理，分析了两种变质处理对钒白口铸铁组织和性能的影响。结果表明，稀土－硅复合变质处理显著改善了碳化物的分布形态，并使铸铁的冲击韧性大幅度提高。     

Microstructure analysis of a bronze–steel electron beam weld

An electron beam welded joint of bronze and steel has been investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The phases and the resulting microstructure in the different zones of the joint have been characterised in detail and compared to hardness. The fine grained microstructure of the weld zone is partly dominated by the directed solidification of the melt. It mainly consists of the α-copper solid solution phase, the intermetallic δ phase Cu₃₁>Sn₈> as well as the bainitic and the martensitic steel phase. This mixture results in a considerably increase in hardness compared to base materials. The heat affected zone of bronze shows a refinement of the used dendritic cast material in a very small area. In the heat affected zone of the mild steel the change of microstructure depends on the distance from the weld zone due to the influence of thermal energy impact and heat dissipation. A maximum of hardness is reached nearby the weld due to the formation of bainite and martensite. The resulting hardness profile is asymmetrical.     

Detection, distribution, and quantification of carbon in steel microstructures by PEELS.

This work concerns the use of parallel electron energy loss spectroscopy (PEELS) to investigate the detection, distribution, and quantification of carbon in various steel microstructures generated by rapid cooling rates or by isothermal transformation. The feasibility of detecting C in steels containing very small amounts of carbon was first examined by calculating the minimum detectable mass fraction for a variety of binary Fe-C alloy specimen thicknesses and microscope conditions. These theoretical studies indicated that the detection of carbon in steel microconstituents containing about 0.01 wt.% (or even less) was easily possible with an analytical transmission electron microscope equipped with a LaB6 emitter and a PEEL spectrometer. These theoretical calculations seemed to be reasonable, as it proved possible to make a quantitative PEELS study of the partitioning between the microconstituents ferrite, retained austenite, and martensite found in an ultralow carbon (0.03 wt.%) steel weld metal provided care was taken to avoid hydrocarbon contamination. Studies of both carbon and molybdenum segregation to ferrite/martensite interfaces in an isothermally transformed Fe-C-Mo alloy were also carried out in order to investigate the nature of the "solute drag" effect in this alloy system.     

亚稳态304不锈钢应力腐蚀影响因素探讨

30 4不锈钢通过低温拉伸制得含有不同马氏体相变量的试样 ,由于冷加工将不可避免地导致位错密度大幅度增加 ,利用铁素体测量仪和透射电镜 (TEM )检测并分析 30 4不锈钢位错形态 .上述试样在 4 2 %MgCl2 沸腾溶液中用慢应变速率法 (SSRT) ,结合金相显微镜 ,扫描电子显微镜等表面分析手段 ,探讨了微观组织变化对 30 4不锈钢应力腐蚀的影响 .结果表明 :由于马氏体相和位错缺陷的交互作用 ,影响了 30 4不锈钢在沸腾MgCl2 溶液中应力腐蚀敏感性 ,且在不同变形量范围内 ,影响的主导因素不同     

金属材料分析国内外标准中波长色散X射线荧光光谱法的应用

对国内外金属材料分析方法标准(包括ASTM、JIS、EN和GB)中应用波长色散X射线荧光光谱法(XRF)的现状,从方法所涵盖的测定元素及其测定的含量范围以及谱线重叠和基体效应的校正等几个方面,并以钢铁分析中的应用为例作了评述。美国材料与试验协会在2012-2016年间先后发布了3个XRF标准方法,分别应用于铸铁、不锈钢、合金钢和低合金钢的分析,测定元素达13项,根据相关钢材的技术规格确定了各元素含量的测定范围。日本工业标准调查会于1997年并于2010年和2013年经修订公布了钢铁XRF分析法JIS标准,可测定各类钢材中主量、次量以及痕量元素达31项,其中镍、铁、钴和测定下限分别延伸至99.5%,50%和60%,从而使此方法有可能扩展应用于镍基、铁镍基和钴基高温合金的分析。我国先后于2007年和2018年由国家标准经主管部门颁布了XRF分析钢铁和高合金钢的两个标准,可测定这2类钢材中的元素为13项和11项,其测定含量范围系根据材料的技术规格确定。关于谱线重叠和基体效应的校正,各标准中在相关部分作了说明,而ASTM有两则独立标准专门论述这两个问题。在此评述对其他金属材料的XRF分析标准也作了介绍(引用文献15篇)。     

电弧炉燃烧-红外法测定碳量与硫量

电弧炉与红外碳、硫分析仪配套，用于测定硅铁、金属锰、矿石、铬铁、钒铁、合金钢铸铁、水泥、微晶玻璃，阳极泥等物质中碳量和硫量，结果满意。     

稀土变质热锻模具铸钢高温磨损性能的研究

研究了稀土（RE）变质热锻模具铸钢的高温磨损性能，并与热锻模具钢H13钢和3Cr2W8V钢进行对比，探讨了稀土元素的作用和热锻模具铸钢的高温磨损机理。结果表明：随着RE加入量的增加，热锻模具铸钢的磨损率先减后增，RE加入量在质量分数为0．05％时热锻模具铸钢具有最佳的高温磨损性能。RE变质热锻模其铸钢的高温耐磨性明最高于H13钢和3Cr2W8V钢。高温磨损机理为氧化磨损和氧化物的疲劳剥落，磨屑为块状的Fe2O3和Fe3O4。     

Synthesis, characterization and corrosion protection study of polypyrrole/phosphotungstate coating on low alloy steel in seawater

Polypyrrole was prepared by chemical oxidation with ammonium persulfate as the oxidant, phosphotungstic acid as the dopant, and its molecular structure was characterized by FTIR spectrum, X-ray diffraction and EDX. A composite coating by using polypyrrole as functional component was prepared on the low alloy steel surface, and its anticorrosion properties were investigated by the open circuit potential and EIS. The results indicated that the coating contained dopant displayed an excellent anticorrosion property for the low alloy steel.     

Study of martensite transformation and microstructural evolution of Cu–Al–Ni–Fe shape memory alloys

In this study, variations in the transformation temperature, crystal structure, and microstructure of the arc melted alloy having nominal composition of Cu–13%Al–4%Ni–4%Fe (in mass%) were investigated for two different treatment conditions, homogenized and heat treated at 950 °C for 1 h. For both conditions, transformation temperature of the alloy was examined by DSC and it was determined as ~200 °C, similar to the value for Cu–Al–Ni alloys given in the literature. The crystal structure of the martensite Cu–13%Al–4%Ni–4%Fe (in mass%) alloy was identified as 18R using XRD. By heat treatment performed at 950 °C, diffraction peaks become more distinct. The microstructure of the alloy was studied with the help of optical microscope as a result of which parallel martensite plates and precipitates were detected. Microhardness value of the alloy was found as 361 and 375 Hv for homogenized and heat-treated conditions, respectively.     

富镧混合稀土对ZL101A合金组织和机械性能的影响

研究了富镧混合稀土对ＺＬ１０１Ａ合金的铸态、固溶态、Ｔ６状态、重熔态的组织和机械性能的影响，提出了混合稀土中入量低压铸造整体车轮合理的热处理状态。