1Cr12Ni2W1MolV钢等离子淬火后的疲劳行为

采用模拟点蚀坑试样，研究了等离子淬火不同温度回火1Cr12Ni2W1MolV钢疲劳裂纹萌生和扩展行为。结果表明，由于等离子淬火的晶粒细化作用和在试样表面引入的残余压应力，提高了末级叶片用钢裂纹萌生抗力。比较两种回火温度试样试验结果，250℃回火试样裂纹萌生和扩展抗力均优于540℃回火试样。本研究结果为选择合适的热处理工艺提供了理论依据。     

2Cr13钢的疲劳裂纹萌生与扩展行为

通过对2Cr13钢进行疲劳裂纹萌生与扩展速率试验,获得该钢在两种不同调质处理下的疲劳裂纹萌生寿命Ni的回归方程、疲劳裂纹萌生门槛值以及裂纹扩展速率da/dN表达式。结果表明,与970℃淬火+710℃回火×6h工艺相比,2Cr13钢在970℃淬火+640℃回火×5h处理后的缺口疲劳裂纹萌生抗力有所改善;当应力强度因子较低时,在640℃×5h回火时的2Cr13钢的疲劳裂纹扩展抗力稍好一些;当应力强度因子较高时则反之。     

热处理对25Cr2NiMo1V钢疲劳特性的影响

对商用25Cr2NiMo1V钢进行了955℃淬火+665℃回火的高压端热处理(HP)和900℃淬火+625℃回火的低压端热处理(LP).通过疲劳实验测定了HP与LP试样疲劳门槛值和疲劳裂纹扩展速率.结果表明,在门槛值区,HP试样门槛值高于LP试样,而其裂纹扩展速率却低于LP试样,HP试样抵抗疲劳裂纹扩展能力高于LP试样.材料抗疲劳裂纹扩展能力的不同是由裂纹的闭合引起的,表面粗糙度诱发裂纹闭合为主要因素.HP试样中回火贝氏体的紧密分布,原始奥氏体晶粒较大以及LP试样中回火马氏体抵抗裂纹扩展能力相对较弱使HP试样中粗糙度诱发裂纹的闭合程度大于LP试样.在Paris区,HP与LP试样的扩展速率相近,裂纹扩展速率对材料微观组织和应力比的影响不敏感.     

5CrMnMo钢的热疲劳裂纹研究SCIEI

通过自制Coffin型及自约束型热疲劳试验机研究了5CrMnMc钢经不同热处理后的热疲劳行为。利用扫描电镜、透射电镜等揭示了热疲劳裂纹萌生及其扩展。结果表明,淬火态的5CrMnMo钢绝大多数热疲劳裂纹优先在晶界处萌生;淬回火态的试样裂纹主要萌生于碳化物与基体的脱开处,或形成晶界裂纹;无论是淬火或淬回火态的试样其热疲劳裂纹主要沿着碳化物与基体脱开处及晶界裂纹桥接而扩展。     

淬火介质温度对渗碳钢表面残余应力和冲击性能的影响

本文研究冷却介质温度从50℃至270℃间淬火对渗碳钢 SAE4130(30CrMo)、SAE1526表面残余应力和冲击断裂性能的影响。介质温度大幅度提高至200℃以上,两种材料的表面残余压应力增加。165℃回火对两种钢的残余压应力数量的降低与所用淬火介质温度无关。SAE4130钢渗碳后不管回火与否,其冲断抗力相对不受介质温度的影响。但介质温度从50℃增至235℃时,SAE1526钢渗碳后淬火试样的冲断抗力随之增加,而回火试样冲断抗力随之减少。介质温度达到270℃时,SAE1516钢渗碳后,不论回火与否都具有最大冲断抗力。介质温度对 SAE1526钢渗碳层冲断抗力的影响与渗层表面形成上贝氏体和下贝氏体有关。     

回火处理温度对40Cr钢疲劳损伤过程的影响

用系统分析方法定义了疲劳损伤变量，结合对试样疲劳损伤过程的扫描电镜观察，在线跟踪了40Cr钢试样及其在不同回火温度下疲劳裂纹萌生期问的疲劳损伤过程。实验结果表明：随着回火温度的上升，40Cr钢的疲劳过程有所不同，使裂纹萌生寿命不断提高，但回火温度与裂纹萌生寿命之问不是简单的线性关系；在450℃以下，随回火温度提高，裂纹萌生寿命明显提高；在450℃至580℃之间，随回火温度的提高，裂纹萌生寿命增加不明显。     

新型热锻模用材DM钢的热处理工艺

通过对新型热锻模用材DM钢组织特征和力学性能的研究,确定了DM钢的最优热处理工艺。DM钢韧性最低的回火温度为600℃,当DM钢性能要求为高硬度时,1060℃淬火540℃两次回火,获得硬度50. 1 HRC;当性能要求为高韧性时,1030℃淬火620℃两次回火,获得冲击吸收能量196. 5 J。-196℃深冷处理后,细小的碳化物均匀分布以及少量的残留奥氏体出现在板条马氏体中,提高材料强度和韧性,阻碍裂纹的萌生和扩展。     

淬火和回火温度对4Cr5MoSiV1钢热疲劳性能的影响

研究了淬火和回火温度对４Ｃｒ５ＭｏＳｉＶ１钢热疲劳抗力的影响，探讨了热疲劳抗力与高温强韧性之间的联系。结果表明：淬火温度从１０００℃提高到１１００℃，热疲劳抗力单调增加；淬火温度一定时，存在一个热疲劳抗力最佳的回火温度；１１００℃淬火＋６２０℃回火具有高的热疲劳抗力。     

40CrNiMoA钢在水介质中的腐蚀疲劳行为

本文对40CrNiMoA钢在870℃淬火200℃回火和1200℃淬火200℃回火两种热处理状态下在蒸馏水中的应力腐蚀和腐蚀疲劳裂纹扩展过程进行了研究,考察了载荷波形、载荷频率、应力比、淬火温度等因素对腐蚀疲劳裂纹扩展特征和裂纹扩展速率da/dN的影响。依据本文的实验结果,对R.P.Wei和Landes提出的用来定量描述腐蚀疲劳裂纹扩展速率的叠加模型进行了计算,得出了该模型适用于40CrNiMoA钢——水介质条件的结论。并给出了可供实际使用的公式、数据和程序。     

H13钢热疲劳性能研究

以盐浴法为手段,对H13钢进行了热疲劳实验,探讨了淬火温度、回火温度、表面处理对其热疲劳失效裂纹的影响并确定了合理的热处理工艺。实验得出:试样热疲劳循环次数在400个周期时,裂纹形成后扩展迅速,裂纹平均生长速度约为2.51×10-3mm/周,而采用1 020℃淬火、640℃回火热处理工艺,与裂纹平均生长速度相比,热疲劳裂纹生长速度减缓了0.45×10-3mm/周,表面渗氮的试样裂纹源可推迟50个热疲劳循环周期。     

Electrical conductivity of 1 : 1 and 2 : 1 clay minerals

The A.C. impedance plots were used as tools to analyze the electrical response of two varieties of Tunisian halloysite 1: 1 and illitic samples 2: 1 as a function of frequency at different temperatures (80–800°C). The real and imaginary parts of the complex impedance trace semicircles in the complex plane. Except for the illite, It-1, the second sample analyzed in this study, these plots give evidence for the presence of both bulk and grain boundary effect, above 600°C onwards. The bulk resistance of the materials decreases with the rise in temperature. Impedance Spectroscopy data reveal a non-Debye type of dielectric relaxation. The Nyquist plots show the negative temperature coefficient of resistance of both pure Tunisian illite and halloysite samples. The results of bulk electrical conductivity and its activation energy are presented for the two mineral clay samples. For illite It-1, the activation energy values estimated from the AC conductivity pattern and modulus pattern are very similar and suggest a possibility of a long-range mobility of charge carriers (ions) via hopping mechanism of electrical transport processes at higher temperature. On the other hand, for the halloysite sample provided from kasserine, (Ha-Kass), the modulus analysis admit that the electrical transport processes of the material are very likely of electronic nature. Relaxation frequencies follow an Arrhenius behavior with the activation energy values not comparable to those found for the electrical conductivity.     

1SRQ1系列全数字软起动器

文章介绍了软起动器的产品特点和主要技术性能指标，并与部分传统控制方式作了一些比较。     

Stabilization of extended stacking faults by {1 1 1}/{1 1 2} twin junction interactions

Extended stacking faults, with lengths of up to 10 nm, that join {1 1 1}/{1 1 2} twin-boundary junctions were observed by high-resolution transmission electron microscopy (HRTEM) in gold thin films. Circuit analysis shows that these defects possess a Burgers vector of 1/3〈1 1 1〉. In order to explain the generation of these extended defects, we consider the behavior of 1/3〈1 1 1〉 dislocations at {1 1 1}- and {1 1 2}-type twin boundaries and near {1 1 1}/{1 1 2} twin-boundary junctions using HRTEM observations and theoretical modeling. By establishing the interaction forces that lead to this defect configuration, our analysis shows that the relief of intrinsic strain at the junction corners, which results from the incompatibility of the translation states at the intersecting boundaries, is sufficient to stabilize the stacking fault extension. Because grain–boundary junctions possess intrinsic strain fields whenever they join boundaries with incompatible translation states, similar mechanisms for stacking fault emission may arise between other closely spaced grain–boundary junctions.     

A contribution to the crystallochemistry of ternary 1:1:1 and 1:1:2 rare earth intermetallic phases with Pb and Pd

The ternary alloys of the rare earths with lead and palladium were studied for the stoichiometric ratios 1:1:1 and 1:1:2 with respect to the structure of these alloys and their existence field. RPbPd (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb) compounds have a hexagonal structure, hP9 Fe₂P type, while RPbPd₂ (R = Pr, Sm, Gd, Tb, Dy, Ho, Er, Yb) alloys have the cubic AlCu₂Mn-type structure (cF16, BiF₃ superstructure).     

20Cr1Mo1V1钢的分级时效工艺研究

研究了 2 0Cr1Mo1V1钢的强韧化工艺。所优化出的分级时效工艺能使其强度和韧性达到质保书的要求。