M35高速钢的热塑性行为

利用Gleeble-1500热模拟试验机进行热拉伸试验,研究了变形温度在950~1150℃范围内,变形速率为0.1 s~(-1)、1 s~(-1)时M35高速钢热塑性行为及断裂机理。结果表明:M35高速钢在试验条件下具有优异的高温塑性,峰值应力随变形温度升高线性下降,随应变速率增加相应升高。热拉伸过程中断裂机制都为韧性断裂,变形温度低于1100℃时断口呈韧窝状,随着温度升高韧窝直径变大、深度增加;变形温度高于1100℃时断口呈沿晶断裂。高温拉伸过程中,碳化物的大小、分布对M35高速钢的热塑性有明显影响。     

23CrNi3Mo钢热塑性行为及断裂机理

利用Gleeble-1500热模拟机进行热拉伸实验,研究了变形温度800~1200℃和应变速率0.002~20 s-1范围内23CrNi3Mo钢热塑性行为及断裂机理。结果表明:23CrNi3Mo钢具有优异的高温塑性。不同的变形温度下,峰值应力随温度线性降低,而随应变速率的增加峰值应力升高。应变速率2 s-1时,热拉伸过程中,高温断裂机制为韧性断裂,断口呈韧窝形貌。随着温度的升高,韧窝直径变小而深度增加。变形温度1050℃时,随应变速率的降低,断裂机制由韧性断裂转变为脆性断裂。应变速率高于0.2 s-1时,断口呈韧窝形貌;而应变速率低于0.2 s-1时,断口呈沿晶断裂形貌。高温拉伸断裂过程中,夹杂物的存在对裂纹的萌生与扩展有一定的影响作用。     

42CrMo高温塑性损伤机理及损伤模型

以42CrMo钢为研究对象,在Gleeble-1500D热模拟试验机上进行高温拉伸实验,研究了变形温度为900℃、950℃、1 000℃、1050℃、1100℃、1150℃,应变速率为0.01s-1、0.1s-1、1s-1、10s-1条件下的高温变形行为,采用Gleeble Fracture Limit(GFL)方法得到相应的应力、应变参数,基于Normalized CockcroftLathamm损伤模型,计算得到不同变形温度和不同应变速率时的临界损伤值,考虑变形温度和变形速率对临界损伤值的影响引入了Zener-Hollomon参数,得到临界损伤值与lnZ值之间的高温损伤模型。采用扫描电镜对拉伸断口进行断口形貌观察,发现大量韧窝及夹杂物的存在,分析得到该断裂机制为韧性断裂。     

热成型钢高温本构数学模型研究

利用Gleeble-1500热模拟试验机对热成型钢的高温塑性变形抗力进行研究。将试样在变形温度800～1100℃下,分别以0.1、1、10和25 s-1应变速率进行单向拉伸试验,分析变形温度、变形速率和变形程度与变形抗力的关系。结果证明,热成型钢是应变速率和温度的敏感材料,变形抗力随应变速率的增加而增加,变形速率在10s-1时的变形抗力是变形速率为1 s-1的2倍以上;变形抗力随变形温度的升高而降低。通过线性回归分析,建立了热成型钢高温塑性本构数学模型,并把理论计算与试验数据进行对比,证明了该模型具有良好的曲线拟合特性。     

M54超高强度钢热塑性行为研究

利用Gleeble-1500热模拟机进行热拉伸试验,研究了应变速率为0.1s-1及变形温度900℃~1200℃范围内高合金超高强度钢热塑性行为,利用扫描电镜,金相显微镜观察分析变形后的显微组织。结果表明,试验钢具有优异的热塑性,在变形温度900℃~1200℃范围内断面收缩率均70%,不同的变形温度下,峰值应力随着温度的升高而降低,热拉伸过程中,M6C碳化物对动态再结晶有促进作用。     

退火态TC4钛合金型材高温拉伸行为研究

采用单向拉伸试验研究了热轧退火态TC4钛合金型材的高温变形行为,分析了变形温度和应变速率对TC4钛合金力学性能的影响。结果表明,当拉伸速率不变时(0.236～1mm/min),抗拉强度随温度的升高而降低;当变形温度分别在773、993和1 093K下保持恒定时,合金的抗拉强度受拉伸速率的影响较小,抗拉强度基本保持不变;当变形温度为1 093K时,合金的抗拉强度随拉伸速率的增加而增加;随着变形温度提高或者拉伸速率降低,断口中韧窝数量越来越多,且韧窝的形状逐渐趋于规则,试样的断裂方式由脆性断裂和韧性断裂的混合型断裂转变为韧窝聚合型延性断裂,最后转变为韧性断裂。     

Effects of Strain Rate and Temperature on Mechanical Property of Nickel-based Superalloy GH3230

对航空发动机用新型镍基高温合金GH3230在不同温度和应变速率下进行了高温拉伸-断裂试验,分析了应变速率和温度对该合金高温力学性能的影响。结果表明,随着应变速率的增加和温度的下降,合金的塑性流动应力有所提高,加工硬化指数下降。从流变应力、应变速率和温度的相关性,得到应变速率敏感系数是一个独立于温度的常量,并计算出GH3230合金的变形激活能=441 kJ/mol。GH3230合金的热变形温度在1273 K左右时,合金在变形过程中能够充分再结晶,并得到晶粒细小、均匀的组织。SEM断口分析表明GH3230合金在高温下（1144~1273 K）应变率范围为10-3~10-1 s-1时的拉伸断裂都是由损伤引起的韧性断裂,且温度对断口形貌影响不大,但应变速率增大会使韧窝尺寸和深浅变小。     

N08020耐蚀合金的热变形性能研究

为揭示温度对N08020耐蚀合金热变形性能的影响,采用Gleeble-3500热模拟试验机对其进行了热拉伸试验,并检测了拉伸后试样的断口形貌及轴向显微组织。结果表明:在900～1 200℃以1 s~(-1)的应变速率拉伸时,合金具有良好的热塑性,断面收缩率为68. 0%～98. 5%,且在1 175℃拉伸时最高;拉伸试样断口均有明显颈缩,且孔洞和韧窝随试验温度的提高而增多、增深,1 200℃拉伸后试样断口的孔洞和韧窝急剧减少,热塑性下降。此外,合金的动态再结晶体积分数随着温度的提高而增大,在1 000～1 200℃拉伸时合金发生了完全动态再结晶,但在1 200℃拉伸的试样断口局部熔融。当应变速率为1 s~(-1)时,N08020耐蚀合金最佳的热变形温度为1 000～1 175℃。     

42CrMo4钢高温拉伸断裂准则与机理的研究

由于变形温度和应变速率是影响42CrMo4钢高温变形损伤断裂行为的重要因素,因此综合考虑了变形温度和应变速率对材料断裂的影响。基于Cockroft-Latham断裂准则,引入温度补偿应变速率因子Zener-Hollomon参数作为修正系数对Cockroft-Latham断裂准则进行改进。通过Gleeble-3800D热模拟试验机对42CrMo4钢进行了温度为950～1100℃、应变速率为0.01～10 s~(-1)条件下的高温拉伸试验。利用试验结果采用线性拟合确定修正系数,得到改进后的断裂准则,将准则预测结果与试验结构对比验证,二则能很好吻合。利用扫描电镜观察试样拉伸断裂断口的组织形貌。结果表明:42CrMo4钢高温拉伸断裂是典型韧窝型韧性断裂,随着温度的提升,材料塑韧性明显提高;随应变速率的提高,材料塑韧性随之不显著降低。     

挤压态镍基粉末高温合金热变形行为与组织研究

通过Gleeble-3500D热力模拟研究了挤压态镍基粉末高温合金在恒温和恒应变速率条件下的热变形行为和组织特征,变形温度范围为950~1150℃,应变速率范围为0.001~0.5 s-1。通过线性回归分析,获得了挤压态镍基粉末高温合金的本构方程,并求得热变形激活能为338.638 kJ·mol-1。在1050℃以下热压缩变形时,试样容易开裂;而在1050~1150℃的温度范围热压缩变形时,试样不易开裂。挤压态镍基粉末高温合金热压缩变形后发生了完全再结晶,再结晶晶粒尺寸受温度影响显著,在低于1100℃变形时,再结晶晶粒尺寸随变形温度升高稍有增大;而在高于1100℃变形时,再结晶晶粒尺寸随变形温度升高显著增大。该种合金的合理变形参数范围为0.001~0.01 s-1及1050~1100℃。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.