汽车拨叉热处理生产设备改造

使用UNICASE型箱式炉进行汽车拨叉热处理,由于该产品技术要求特殊,需要对原有设备进行改造。碳势控制系统由原来的红外线CO2气体分析仪改为氧探头,提高了碳势控制的速度和精度.选用合适的淬火用油,并对油槽搅拌系统进行改造,以满足产品变形要求。改造了滴注系统,提高了炉气均匀性。     

8620H钢拨叉的热处理

8620H钢拨叉单件质量1.05kg,需进行碳氮共渗和淬火、回火处理,达到表面硬度680~800HV0.3、心部硬度30~45HRC和至550HV0.3的有效硬化层深度0.1~0.3mm。采用UBG渗碳炉对拨叉进行了3次碳氮共渗及淬火和低温回火工艺试验,通过适当缩短碳氮共渗时间、降低淬火温度、调整淬火油温及其搅拌烈度,最终达到了拨叉的质量要求要求。     

纳米WC粉氢处理脱除游离碳的研究

将高碳含量的纳米WC粉末在氢气流中进行热处理脱除游离碳,研究处理温度、保温时间和H2流量等工艺参数对WC粉碳含量及粒度的影响.结果表明,在温度为940℃,H2流量为3.5L/min,保温时间为100min的工艺条件下,可以将碳含量由9.74%降低至6.20%,处理后纳米WC颗粒无明显长大.当处理温度高于970℃会导致WC化合碳损失而生成W2C相,并造成WC颗粒长大.     

滴注式碳氮共渗炉气氛的调节控制

本文介绍了用甲醇做载体气,煤油为渗碳气,同时添加氨气的滴注式碳氮共渗在密封箱形炉中试验研究的成果。本工艺特点是炉气氮势可稳定调节,在此基础上能实现炉气碳势的控制。本文并就添加氨对渗碳气组成、炉气碳势控制和氮势调节机理进行了分析探讨,认为添加氨对渗碳气主要起稀释作用,对渗碳中Boudouard反应不起干扰,以CO_2能区分炉气氮势和调节控制碳势。添加氨量和炉气氢分压有关,其加入量可根据氮势要求进行推算,指出了用测定残留氨或含氢量控制炉气氮势的可能性。     

炉内气氛控制方法

本发明提出了钢铁热处理炉内气氛控制的改进方法。载气用甲醇和氮气混合气制成。根据甲醇和氮气流量以及添加气(如甲烷)流量与炉气中CO含量的相互关系,采用本发明,测量炉内合适位置或不同位置气氛中的CO含量,调节甲醇和(或)氮气流量,使气氛中CO含量保持在要求值。同时,通过对于测碳势敏感的各种方法,来控制改变炉气碳势的添加气的量或流量。根据本发明的一个具体方面,调节甲醇和氮气流量保持所要求的CO含量而不影响炉气的碳势,调节添加气(甲醇气)流量,保持所需要的碳势而不影响炉气氛的碳势。根据发明的另一个具体方面,气氛中CO含量以及气氛碳势是分别控制的,能做到     

气体多元共渗控制系统

本发明为气体多元共渗控制系统．是为了实现对氮、碳、硫、铬低温气体多元共渗工艺进行的智能化控制。可按要求的温度、气体流量、保温时间等工艺参数实行自动控制，并将实际工艺实施过程中的温度、气体流量、保温时间等参数全部进行记录。对实施的低温气体多元共渗工艺，根据用数学模型与编制的软件．可以计算实际工艺实施过程中渗层中的氯浓度，并计算出氮势等参数。并根据所用的数学模型与编制的软件，     

拨叉加工弹塑性变形矫正技术研究与分析

针对拨叉在加工过程中所产生的弹塑性变形问题,提出利用动头的超声振动运动对拨叉的加工弹塑性变形进行矫正。首先,利用弹塑性理论对拨叉的变形机理进行分析,并通过有限元仿真得出了拨叉的弹塑性变形规律曲线。然后,采用二分法计算拨叉变形矫正参数,并获得了拨叉弹塑性变形矫正的规律性曲线,建立了拨叉变形矫正的数学模型;提出了超声振动矫形的方法,并对超声振动系统进行了设计,利用ANSYS Workbench对超声振动系统进行模态仿真分析,得出系统最佳工作频率为20 kHz。最后,对振动矫形系统的矫形效果进行了分析,验证了振动矫形方法的可行性与合理性。     

摩托车拨叉锻件锻造工艺

通过对目前国内摩托车拨叉锻件锻造工艺分析，介绍了摩托车拨叉的几种锻造方案，通过比较，对不同工况的拨叉生产作了工艺推荐。     

高压泥浆阀阀板及阀杆的气体渗氮

高压泥浆阀板和阀杆材料分别为35CrMo钢和1Cr13不锈钢,在200℃左右的腐蚀性介质中服役,均要求进行渗氮处理,以提高其耐磨性和耐蚀性。经过多次试验,最终确定采用氮碳共渗,工艺参数为:对于阀板,温度530～540℃,保温时间约10 h,保温期前7 h氨分解率30%～40%,乙醇约1 ml/min,后3～4 h氨分解率60%～80%,乙醇约1.5 ml/min;对于阀杆,温度为500～520℃,其余参数同阀板。     

超细晶碳化钨-钴复合粉短流程制备工艺研究

以偏钨酸铵、醋酸钴及葡萄糖为原料,采用短流程工艺,通过喷雾转化法制备出含W、Co等元素的前驱体粉末、煅烧制备W、Co的氧化粉、最后以低温连续还原碳化法制备出WC晶粒尺寸约为260 nm的WC-Co复合粉。研究了短流程工艺3个关键步骤的参数变化对粉末形貌、粒径、氧含量、总碳和化合碳含量等特征的影响。结果表明,当溶液浓度为60%、进料速度为2 000 mL/min、离心转速为12 000 r/min时,制备的前驱体粉末粒度分布均匀,相互粘结的现象较少。温度为550℃、保温时间20 min时煅烧前驱体制备出的氧化物粉末粒度较均匀。当低温连续还原碳化温度为900℃、氢气流量为1.3 m3/h、保温时间为60 min时,可获得WC晶粒细小均匀、总碳和化合碳较为一致且接近于理论碳含量的WC-Co复合粉。     

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.     

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。     

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.