热处理对45CrNiMoV钢析出相和力学性能影响

通过扫描电镜(SEM)、透射电镜(TEM)观察及硬度、拉伸性能测试,利用正交实验方差分析,研究了不同回火温度对45CrNiMoV高强钢析出相形貌和力学性能的影响。结果表明,实验钢回火温度对强度和冲击功均有显著影响,550℃回火后强/硬度达到最高值,600℃以上回火强/硬度急剧下降;实验钢回火温度从570℃提高到640℃,析出的碳化物形貌由条杆状向球形演变,570℃回火后,析出的细小的球状碳化物对马氏体板条边界存在钉扎作用。640℃回火后,析出的碳化物已经无法钉扎住板条边界;实验钢最佳热处理工艺为880℃油淬保温45 min+590℃回火240 min。     

55NiCrMoV7钢的回火组织与性能

研究了55NiCrMoV7钢在100℃～700℃、90s～665h之间回火后的组织和硬度变化。结果表明，钢中的原奥氏体晶粒、马氏体板条不因回火过程而改变，回火析出碳化物的体积分数在一定回火温度、时间范围内保持恒定，但是碳化物的形态和尺寸随回火工艺而改变。钢的回火硬度与碳化物的等效直径、钢的弹性极限以及钢的弥散硬化密切相关。     

回火温度对N63钢组织及力学性能的影响

采用扫描电镜和透射电镜等手段研究了回火温度对N63钢组织及性能的影响。结果表明，N63钢具有良好的抗回火稳定性，260～600℃回火几乎未生成逆转变奥氏体，该温度区间内低温回火的析出相主要为ε-碳化物，当回火温度升高至480℃附近时基体析出M₂C碳化物，抗拉强度和屈服强度分别达到峰值，为1483 MPa和1138 MPa,然后随回火温度的升高迅速下降，600℃回火时抗拉强度仅为1009 MPa,此时N63钢马氏体基体板条分解严重，析出相为渗碳体和M₂₃C₆;冲击吸收能量随回火温度先下降后升高再下降，420℃回火冲击吸收能量最低，为79 J。综合不同回火温度下的微观组织和力学性能，N63钢在480℃回火具有优异的强韧性匹配。     

列车车钩用ZG25MnCrNiMo钢的冲击性能研究

研究火车车钩用钢ZG25MnCrNiMo经过不同调质工艺处理后-40 ℃的冲击性能.分别用金相显微镜、扫描电镜和透射电子显微镜观察和分析钢的微观组织、低温冲击断口形貌和钢中碳化物的析出行为.结果表明,ZG25MnCrNiMo钢在910 ℃淬火、550 ℃回火2 h得到均匀回火索氏体组织,冲击功最大.冲击功随回火温度的升高而增大.低于550 ℃回火,钢中的碳化物主要在板条界面呈连续析出,-40 ℃冲击功低;550～650 ℃回火,铁素体呈等轴状且碳化物分布于晶内,表现出高的冲击性能.     

深冷处理后回火温度对15Cr超级马氏体不锈钢组织及耐点蚀性能的影响

利用场发射扫描电镜、透射电镜以及电化学综合测试系统对15Cr超级马氏体不锈钢(SMSS)经不同热处理工艺处理后的显微组织变化和第二相碳化物及其对该钢腐蚀行为的影响进行了研究。结果表明,试验钢经不同热处理工艺处理后组织均由板条马氏体、奥氏体以及M₂₃C₆型碳化物颗粒组成,随着回火温度的增加,试验钢中逆变奥氏体含量增加,且在650 ℃回火时达到体积分数最大值41.41%。当回火温度高于600 ℃时第二相碳化物开始析出,且650 ℃回火后碳化物数量及尺寸较600 ℃增多。点蚀电位随着回火温度的增加而降低,第二相碳化物的析出降低了试验钢的点蚀电位,促进了亚稳点蚀位置的形成,从而降低了试验钢的耐腐蚀性能。     

回火温度对加工器械用钢组织及力学性能的影响

利用投射电子显微镜和万能试验机对不同回火温度下加工器械用钢的力学性能和显微组织进行研究。结果表明:随着回火温度的升高,试验钢的抗拉和屈服强度都减小,其伸长率和冲击韧度呈上升趋势;当回火温度较低时,钢中析出大量碳化物,提高了其强度;当温度升高,析出的碳化物宽度变窄,试验钢脆性增加;当回火温度进一步升高后,钢中局部出现铁素体晶块;当回火温度为550℃时,纳米级碳化物析出,起到了细晶强化作用。     

SDCM1新型热作模具钢回火过程中碳扩散行为的电阻表征

采用原位电阻法,并结合硬度测量、微观组织分析技术对SDCM1新型热作模具钢从室温至590℃回火过程中的碳原子扩散行为进行了研究.结果表明:在80℃至125℃回火时,试验钢的电阻偏离线性出现下降趋势,同时硬度出现峰值,这主要是由于碳原子向位错扩散所致,其激活能为83 kJ·mol-1;180～250℃回火时,电阻偏离线性略微降低,归因于ε碳化物的形核;300℃以上回火时,电阻随温度升高增势减缓,结合透射电镜(TEM)分析,这主要是由于碳化物的析出所致,通过电阻的不同演化趋势可以判断碳化物和合金碳化物的析出差异;温度升高至590℃等温时,试验钢的电阻急剧下降,这主要是由于等温碳化物的大量析出所致.研究表明电阻法可以清晰表征模具钢的回火过程中碳原子运动、占位及组织演化特征与动力学过程,是一种有效的研究手段.     

回火温度对E690钢碳化物析出量的影响

利用内耗方法并结合显微组织与显微硬度分析,研究了回火温度对高性能海洋平台用E690钢碳化物析出量的影响。结果表明:在相同的回火时间条件下,回火温度对碳化物的析出量有较大影响,与淬火态试样相比,在550、600和650℃回火20 min后试样中的固溶碳析出量分别为86%、90%和94%,经690℃保温20 min回火处理后试样中的固溶碳析出量达到96%;回火温度越高,碳化物完全析出所用时间越短,适当升高回火温度,可以有效地缩短回火时间。     

超高强度钢中M_2C和β-NiAl相的复合析出强化行为

采用透射电镜(TEM)、X射线衍射分析仪(XRD)以及拉伸试验机对超高强度钢中的碳化物和金属间化合物的复合析出强化行为进行了研究。结果表明:在300℃回火时,主要析出大量的ε-碳化物,此时试验钢的强度升高,冲击性能略有降低;在430℃回火时,析出大量的粗大片状渗碳体,试验钢的强度继续提高,但冲击吸收能量迅速降至最低值;随着回火温度继续升高,渗碳体发生溶解,M_2C型碳化物、金属间化合物β-Ni Al相以及逆转变奥氏体开始在马氏体基体中开始析出,试验钢的抗拉强度和硬度值在470℃达到最大,屈服强度在490℃达到峰值。由于M_2C型碳化物、金属间化合物β-Ni Al相和薄膜状逆转变奥氏体的复合析出作用,试验钢在510℃回火5 h后,具有最佳的综合力学性能。当回火温度继续升高,M_2C型碳化物和逆转变奥氏体都发生粗化,钢的强度和冲击性能都有所降低,且经560℃回火后逆转变奥氏体含量达到最大值。     

M50钢碳分配过程中的组织演化

分别在300℃和450℃下对淬火态M50钢进行了碳分配处理,并利用X射线衍射仪(XRD)、扫描电镜(SEM)及透射电镜(TEM)对碳分配后试样进行观察分析,研究传统Q-T(淬火-回火)和新型Q-P-T(淬火-碳分配-回火)热处理工艺对M50钢性能的影响。结果表明:经碳分配后M50钢中残留奥氏体的碳含量由淬火态的0.64 mass%,最高升至1.20 mass%(300℃,30 min)及1.10 mass%(450℃,0.5 min);不同温度下,随着保温时间的延长,残留奥氏体的碳含量降低;碳分配时M50钢中存在碳化物的析出,随着时间的延长,碳化物析出量逐渐增加,碳分配过程中析出的碳化物为Fe3C;新型Q-P-T热处理工艺可以在保证M50钢强度的前提下,将其冲击吸收功提高90%以上。     

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.     

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。     

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.     

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.