机械齿轮钢渗碳热处理变形行为研究

以20Cr2Ni4A和钒微合金化的齿轮钢为对象,研究了其在不同淬火方式下的变形行为,并分析了渗碳热处理过程中渗碳深度与组织演变规律。结果表明,随着淬火方式从空冷到水冷再到油冷,齿轮用钢的平均变形率逐渐上升。油淬热处理后齿轮钢的有效硬化层深度大于空淬热处理。经过油淬处理后,齿轮钢组织中含有细小的马氏体组织,使得其显微硬度高于具有贝氏体+马氏体组织的空淬处理齿轮钢。     

X38CrMo16模具钢模坯淬冷温度场仿真与参数选择

X38CrMo16属于抗腐蚀性能优良的塑料模具钢,因导热性能较差和淬冷参数控制不当常常导致大件淬火开裂或心部未淬透现象发生.为解决这一问题,体文运用有限元法对尺寸为1700mm×280mm×650mm的X38CrMo16模块油淬温度场进行了仿真计算,并根据CCT曲线确定了模块油淬-空冷的转换时机,完成了模块淬冷参数的虚拟设计.结果表明,为减少淬火应力和避免心部珠光体组织转变,模块油中冷却时间控制在40～46min为宜,此时模块心部预测温度在576～665℃之间;按此淬冷工艺执行后,X38CrMo16模块淬火缺陷基本上得以消除,实现了淬冷过程的计算机预演.     

基于田口方法的大型Cr5钢支承辊喷雾淬火工艺优化

为了提高大型Cr5锻钢支承辊的综合力学性能,论文基于数值模拟技术,并采用田口方法,以某大型Cr5锻钢支承辊喷雾淬火后辊身表面与中心温差、淬硬层深度以及轴向残余拉应力为性能指标,以淬火温度、淬火方式、冷却时间和介质温度为控制因子,以工件的转移时间、环境温度和淬火温度测量误差为噪声因子,对该大型Cr5锻钢支承辊的喷雾淬火工艺进行了优化。通过方差分析得到了影响各性能指标的显著因素,并经综合分析给出了其最佳喷雾淬火工艺。结果表明,优化后的喷雾淬火工艺能有效降低支承辊辊身中截面的温度梯度,提高支承辊的淬硬层深度,并显著降低支承辊的淬火残余拉应力。     

Cr12型钢模具线切割的开裂和防止

<正> Cr12型钢热处理变形微小,断面在200～300mm的模具淬火能完全被淬透。这种钢不仅可用油冷,即使硝盐或空冷也可淬硬。 在我厂生产的冷作模具中,Cr12型钢材占80％以上。但此类钢材在电火花线切割加工过程中,或加工完毕后,模具开裂时有     

不锈塑料模具钢模块喷淬系统研究

模具钢模块在淬火过程中易出现水、油浸淬开裂、变形且淬火油会污染环境,空淬组织硬度不均匀等缺陷,为克服上述缺陷,设计并研制一套喷水淬火系统,选4Cr13模块对喷水淬火系统进行了初步试验,试验结果表明,用此系统喷淬的模块硬度均匀,无变形,可以避免开裂现象。     

机床导轨表面淬火处理技术

研究了淬火工艺参数，特别是淬火移动速度对导轨表面硬度、淬火层深度、变形量以及产生裂纹的倾向的影响，以及铸件的化学成分对表面硬度、淬硬层深度的影响。通过对床身加压处理，使机床导轨在精刨后凸起，减小淬火后导轨的变形量，可以保证导轨磨削处理后，仍有有效的硬化层深度。同时，介绍了导轨表面缺陷的各种修补方法以及优缺点。     

新型冷连轧机支承辊的制造

为满足冷轧机支承辊高的技术要求(辊身硬度、硬度均匀性、硬度梯度、淬硬层深度、残余应力控制),在常规Cr5材质基础上通过化学成分调整,经水雾调质预备热处理和差温淬火最终热处理制备了新型冷连轧机支承辊。所制备轧辊化学成分、组织及力学性能均满足技术要求,无损探伤未发现超标缺陷。在某冷连轧机使用,各项指标稳定、正常、安全,平均毫米轧制吨位达5万吨。     

Cr3支承辊表淬加热保温时间与有效淬硬层深度的关系

利用DEFORM软件模拟计算并结合实测数据,研究了Cr3支承辊表淬加热时保温时间对有效淬硬层深度的影响,最终给出了Cr3支承辊表淬加热保温时间与有效淬硬层深度之间的关系图。     

25CrMo钢端淬试验改进与淬透性分析

为了克服常规端淬试验中25Cr Mo钢试样在空气中发生淬火现象,提出了一种改进的加套管的末端淬火试验方法。通过显微组织观察、定量金相和硬度测量,分析了25Cr Mo钢的显微组织与淬透性。结果表明,改进的端淬试验能够使热量沿轴向传递,避免了产生边角效应。端淬后的试样由水冷端向空冷端的显微组织依次为马氏体、马氏体+贝氏体、贝氏体。25Cr Mo钢淬硬层深度可达20 mm,具有良好的淬透性。     

40Cr钢量化水淬应用研究

研究了量化水淬对40Cr钢淬硬层深度及淬火畸变的影响,将其与普通水淬和油淬进行了比较。结果表明,当量化水淬的工艺参数K=3、Ts=70℃时,主要冷却特性参数分别为Vmax=93℃·s-1、V300=68℃·s-1、t200=20.5s时,40Cr钢量化水淬的冷却能力介于普通水淬和普通油淬之间,其表面硬度为58HRC、硬化层深度为4.60mm、淬火畸变平均值为0.093mm,也介于普通水淬和普通油淬之间。     

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.     

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.     

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.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.