High-Temperature Oxidation Behavior of 5Cr21Mn9Ni4N Steel Micro-Alloyed by Rare Earth

The oxidation resistance of 5Cr21Mn9Ni4N steel micro-alloying by RE at 700 - 900 ℃ was investigated. The results indicate that oxidation exponent n and oxidation activation energy are increased, and oxidation velocity constant kp is decreased when 0.2% RE is added in 5Cr21Mn9Ni4N steel. The addition of RE elements does not alter phase constitution of oxidation scale, however it improves the configuration of oxidation scale, and increases thermal stability and adhesivity of oxidation scale, which results in the raise of oxidation resistance of 5Cr21Mn9Ni4N steel at high temperature. The oxidation scale constitutes of refractory steel transfer from manganic oxide mostly to ferric oxide mostly with the increase of temperature, which leads to descend of compactness and desquamation resistance of oxidation scale. The mass increase of ferric oxide in the oxidation scale and the looseness of oxidation scale are the main reason to descend the oxidation resistance of refractory steel.     

6Cr21Mn10MoVNbN气阀钢晶粒长大及其动力学研究

研究了6Cr21Mn10MoVNbN气阀钢在1 000℃到1 250℃固溶处理时的晶粒长大规律,并分析了等温固溶时晶粒长大的动力学.结果表明,弥散分布的碳氮化物对晶粒长大有显著阻碍作用,在低于该钢的晶粒粗化温度(1150℃)固溶处理时,大量未溶解的碳氮化物使得晶粒尺寸增幅较小、洛氏硬度小幅下降;在高于1150℃时,随温度的升高或时间延长,晶粒长大迅速,洛氏硬度大幅下降;晶粒生长指数随固溶温度的升高而呈台阶式增长;在固溶温度为1 050～1100℃下的晶粒长大激活能为189.9 kJ/mol,晶粒长大机理为自扩散过程控制机理,并建立了相应的晶粒长大动力学方程.     

Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth （RE） amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2% in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10^-6 -10^-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0.10%-0.20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0. 2% which leads to a largely improved high temperature mechanical property.     

5Cr21Mn9Ni4N钢中碳化物层状析出与晶界沉淀

用光学，扫描和透射电镜观察研究了Ｍ２３Ｃ６晶界“层状”析出和类珠光形成规律和组织特征。     

Effect of Rare Earth Elements on Austenite Growth Dynamics of Steel 9Cr2Mo

ＥｆｆｅｃｔｏｆＲａｒｅＥａｒｔｈＥｌｅｍｅｎｔｓｏｎＡｕｓｔｅｎｉｔｅＧｒｏｗｔｈＤｙｎａｍｉｃｓｏｆＳｔｅｅｌ９Ｃｒ２ＭｏＹａｎｇＱｉｎｇｘｉａｎｇ；ＷａｎｇＡｉｒｏｎｇ；ＧａｏＭｉｎｇ；ＷｕＨａｏｑｕａｎ；ＧｕｏＴｉｅｂｏＧａｏＭｉing;Ａｂｓｔ...     

0Cr21Ni6Mn9N奥氏体不锈钢的应变强化行为

研究了不同氮含量的0Cr21Ni6Mn9N奥氏体不锈钢的塑性流变行为。结果表明,其形变强化特性可用Ludwigson模型来表示。钢在不同的应变下表现出不同的塑性流变行为,存在一个瞬变应变。当应变量低于它时,流变行为与Ludwik方程存在一个正偏差;而应变量高于它时,则符合Ludwik模型。造成这一差异的主要原因是位错滑移模式发生了改变,低于瞬变应变时为单系滑移,高于瞬变应变时为多系滑移。氮对位错滑移模式的影响主要表现为对瞬变应变的影响。随氮含量的增加,瞬变应变被推向更高的水平,这意味着氮原子使位错在更大的应变下才产生多系滑移和交滑移。     

工艺参数对5Cr21Mn9Ni4N钢塑性的影响

本文讨论了热变形和冷变形工艺参数对５Ｃｒ２１Ｍｎ９Ｎｉ４Ｎ钢塑性的影响，提出大断面钢坯锻轧温度为１１００℃，小断面钢坯开轧温度为１１８０℃，并用冷轧代替冷拔成材的工艺流程。     

Grain Growth Behavior in Sintered Nd-Fe-B Magnets

The Nd2Fe14B grain growth behavior in sintered Nd-Fe-B magnets was quantitatively described.The effects of sintering temperature and time,and alloy powder size and its distribution on grain growth process were analyzed.Hence,possible grain growth mechanisms in these magnets were qualitatively discussed.The Nd2Fe14B grain growth proceeded at quite a high rate in the initial 0~1 h of sintering and from then onwards the grain growth rate decreased.A large average particle size or a wide particle size distribution of initial alloy powders was found to remarkably accelerate the grain growth process and even result in the occurrence of abnormal grain growth.On the basis of experimental results,two grain growth mechanisms were considered to operate during sintering of Nd-Fe-B magnets,that is,dissolution and re-precipitation of Nd2Fe14B particles,and Nd2Fe14B particle growth by coalescence.It was believed that Nd2Fe14B particle growth by coalescence not only produced a large average grain size and a wide grain size distribution,but also was the fundamental reason for the formation of abnormally large grains in the microstructure of sintered Nd-Fe-B magnets.     

Effect of Rare Earth on Thermal Shock Resistance of Steel 9Cr2Mo

Ｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓｈａｖｅｂｅｅｎａｄｄｅｄｉｎｔｏｈｏｔｒｏｌｌｅｒｓｔｅｅｌ.ＲＥｅｌｅｍｅｎｔｓｃａｎｉｍｐｒｏｖｅｔｈｅｒ ｍａｌｆａｔｉｇｕｅ[1] ,ｌｏｗｆｒｅｑｕｅｎｃｙｆａｔｉｇｕｅ[2 ] ,ｐｌａｓ ｔｉｃｉｔｙａｎｄｔｏｕｇｈｎｅｓｓ[3] ,ｒｅｆｉｎｅａｕｓｔｅｎｉｔｉｃｇｒａｉｎｓｉｚｅ[4] ａｎｄｍｏｄｉｆｙｉｎｃｌｕｓｉｏｎｓ[5 ] ｏｆｈｏｔｒｏｌｌｅｒｓｔｅｅｌ 6 0ＣｒＭｎＭｏ .Ｓｔｅｅｌ 9Ｃｒ2Ｍｏｉｓａｔｒａｄｉｔｉｏｎａｌｃｏｌｄｒｏｌｌｅｒｓｔｅｅｌ.Ｗｈｅｎ…     

VHD法吹氮气冶炼气阀钢5Cr21Mn9Ni4N

随着我国汽车制造业的发展，气阀钢５Ｃｒ２１Ｍｎ９Ｎｉ４Ｎ的市场需求量逐渐增加。生产中，由于氮化铬铁曾出现过短缺，影响正常生产。为减少氮化铬铁使用量，开始使用同钢种返回料，实验证明采用ＶＨＤ法吹氮气增氮工艺简单、易行，较好地解决了含氮钢生产过程中存在的...     

Effect of Rare Earth Elements on Quenching Crack Resistance of Steel 9Cr2Mo

Ｒｏｌｌｅｒｆｏｒｃｏｌｄｒｏｌｌｉｎｇｉｓａｋｅｙｆｏｒｇｉｎｇｐａｒｔ,ｗｈｉｃｈｅｘｐｅｒｉｅｎｃｅｓｃｏｎｔａｃｔｓｔｒｅｓｓ ,ａｌｔｅｒ ｎａｔｉｎｇｓｔｒｅｓｓａｎｄｆｒｉｃｔｉｏｎａｌｓｔｒｅｓｓｄｕｒｉｎｇｒｏｌｌｉｎｇ .Ｔｈｅｒｅｆｏｒｅ ,ｈｉｇｈｅｒｓｔｒｅｎｇｔｈ ,ｓｕｒｆａｃｅｈａｒｄｎｅｓｓ,ｗｅａｒｒｅｓｉｓｔａｎｃｅａｎｄｅｎｏｕｇｈｔｏｕｇｈ ｎｅｓｓｓｈｏｕｌｄｂｅｃｏｎｓｉｄｅｒｅｄｆｏｒｍａｎｕｆａｃｔｕｒｉｎｇｔｈｉｓｃｏｌｄｒｏｌｌｅｒ[1] .Ｓｉｎｃｅｔｈｅ…     

Rare Earth Doping Effects on Properties of Ceria-Zirconia Solid Solution

Ce0.6Zr0.3RE0.1O2(RE=Y, La, Pr, Tb)solid solutions were prepared by co-precipitation technique and characterized by a series of methods. XRD and FT-Raman results show that Ce0.6Zr0.3RE0.1O2 has cubic fluorite structure. The different dopant ion radii bring different effect on the cell parameter of Ce0.6Zr0.3RE0.1O2. The X-ray photoelectron spectroscopy (XPS) results show that the binding energy of Ce3d, Zr3d and O1s for Ce0.6Zr0.3RE0.1O2 rises compared with that for Ce0.6Zr0.4O2, indicating that dopant elements change chemistry environment of solid solutions which is available to improve redox performance. Compared with Pd/Ce0.6Zr0.4O2, doping Y and La does not change air/fuel (A/F) characteristic of TWCs, but doping Pr and Tb widens A/F operating window and makes HC, CO and NO have higher conversion. The light-off temperature of Pd/Ce0.6Zr0.3La0.1O2 is corresponding to that of Pd/Ce0.6Zr0.4O2. However, the light-off temperatures of Pd/Ce0.6Zr0.3M0.1O2 (M=Y, Pr, Tb) are lower than that of Pd/Ce0.6Zr0.4O2, which keep much lower after high temperature treatments. Among Pd/Ce0.6Zr0.3RE0.1O2, Pd/Ce0.6Zr0.3Tb0.1O2 represents wider A/F operating window, higher conversion, lower light-off temperature and better high-temperature resistance.     

00Cr21Ni2Mn5N双相不锈钢的高温变形

采用Gleeble-3800热/力模拟实验等方法研究了00Cr21Ni2Mn5N奥氏体-铁索体双相不锈钢(LDSS)在温度为850～1150℃、应变速率为5～50s^-1,压下量60%的热变形行为及组织变化。结果表明,00Cr21Ni2Mn5N双相不锈钢的流变应力随温度的增加而降低,随应变速率的增加而增加,该钢的软化机制与Zener-Hollomon(Z)参数有关,00Cr21Ni2MnSN双相钢的表观应力指数为4.82,热变形表观激活能(Q)为219 kJ/mol     

Electronic Theoretical Study of the Interaction between Rare Earth Elements and Impurities at Grain Boundaries in Steel

Rareearths(RE)aresurfaceactiveelements ,theirapplicationsinmetalmaterialscanbesum marizedaspurification ,modificationandall oying[1～ 3 ] .Itisaveryattractivesubjectthattheinter actionofREelementswithlowmeltingpointimpuri tiesintheregionofGBs ,suchasP ,S ,As ,Sbandsoon .ResultsofexperimentsshowthatsegregationinGBsofasmallamountofREinsteelrestrainsharmfulimpuritiessuchasP ,S ,As ,Pb ,Sb ,tosegregateto wardsGBs ,soREelementscancleanseandenhanceGBs ,therebyimprovethehightemperatureducti…     

Effect of Rare Earth Elements on Quantity Growth of Crops

Ｒａｒｅｅａｒｔｈ (ＲＥ)ｍｉｃｒｏ ｆｅｒｔｉｌｉｚｅｒｓｈａｖｅｂｅｅｎｕｓｅｄｉｎａｇｒｉｃｕｌｔｕｒｅｐｒｏｄｕｃｔｉｏｎｉｎＣｈｉｎａｓｉｎｃｅ 1 970ｓ ,ａｎｄｔｈｅｓｅｍｉｃｒｏ ｆｅｒｔｉｌｉｚｅｒｓａｒｅｓａｌｔｓｏｆｍｉｘｅｄＲＥｓ ,ｗｈｉｃｈｍａｉｎｌｙｉｎｃｌｕｄｅＬａ ,Ｃｅ ,ＰｒａｎｄＮｄ[1,2 ] .ＰｒｅｖｉｏｕｓｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｔｈｅＲＥｉｎｓｕｒｆａｃｅｓｏｉｌａｌｍｏｓｔｄｏｅｓｎｏｔｍｉｇｒａｔｄｏｗｎｗａｒｄａｔａｌｌａｎｄｔｈｕｓｂｅａｃｃｕｍｕｌａ…     

TB8钛合金晶粒长大行为的研究

研究了TB8钛合金冷轧板材在不同热处理温度和不同保温时间下的晶粒长大行为。结果表明:TB8钛合金冷轧板材在820~880℃的温度范围内不存在晶粒急剧粗化的现象,可以在此区间内的温度下对其进行热处理,保温时间根据温度的不同可在30~120 min范围内选择。此外,借助Beck方程和Arrhenius方程分别计算得到该合金的晶粒生长指数(n)为0.25~0.35,β晶粒长大激活能(Q)为273.23 k J/mol。     

Influences of Molybdenum and Rare Earth on Mechanical Properties of ZG30Cr

Alloying is an important method to improve properties of casts. The influences of Mo and RE on the mechanical properties of ZG30Cr were investigated in this work. A good comprehensive mechanical properties of the alloy with 0.3% Mo and 0.1% RE were obtained. The elongation, tensile strength, impact toughness and hardness of the alloy reaches 7.21%, 577.49 MPa, 91.7 J·cm-2 and HRC 24.6, respectively.     

长期时效对GH4199合金组织和性能的影响

 采用金相和电镜微观组织观察、室温和高温拉伸试验、物理化学相分析等综合试验方法，对经600、700、800、900 ℃和100、200、500、1 000 h长期时效处理的GH4199合金进行测试和研究。结果表明，GH4199合金经长期时效后，其室温和高温力学性能仍保持在较高水平；合金的组织稳定性良好，析出相主要为γ′相和碳化物。据相分析结果可知，在700~900 ℃时效1 000 h左右，合金组织中存在极微量的脆性(TCP)相——μ相和σ相，它们对合金的力学性能基本无影响，组织中虽然存在微量TCP相，但合金的室温和高温塑性不发生“脆化”。     

00Cr21Ni6Mn9N高强度不锈钢管的试制

00Cr21Ni6Mn9N属于超低碳高氮不锈钢,在试制过程中该钢存在强度高、塑性差、晶间腐蚀不合等迫切需要解决的问题。通过大量的试验发现变形量是影响该钢力学性能的主要因素;而前一加工道次的退火温度对强度基本无影响,对塑性有一定的影响,同时该钢在制管过程中内表面形成较厚的残留氧化物,如果不采取特殊手段进行清理,也将在一定程度上影响其晶腐性能,通过调整变形量和改进酸洗工艺这些因素的研究,成功试制出8个规格的合格的钢管。     

Effect of Rare Earth Elements on Isothermal Transformation and Microstructures in 20Mn Steel

The effect of rare earth elements on the isothermal transformation and microstructures in 20Mn steel is in-vestigated by means of metallography and dilatometry.Rare earth elements decrease both the incubation periodof pro-eutectoid ferrite and the rate of pearlitic transformation.In addition,rare earth elements play a role ofreducing needle-like ferrite and the amount of pearlite,densifing the lamellar space of pearlite and enhcingsegregation of carbide in granular bainite.It is suggested that rare earth elements may decrease the interfacialenergy of grain boundary and interphase,hinder the diffusion of carbon atoms and form rare earth carbides withhigh melting point which reduce the carbon content in austenite.