1Cr11MoNiW1VNbN钢气体渗氮方法研究

研究了一种对1Cr11Mo Ni W1VNb N钢进行气体渗氮的工艺方法,采用较高温度在奥氏体区渗氮,通过多次试验摸索出一种较好的工艺方法,并用显微镜、硬度计等对渗氮后试样的渗层深度、裂纹情况、表面硬度、阶梯硬度等进行了测试分析。结果表明:采用温度(625±5)℃渗氮、(640±5)℃退氮的三段渗氮方法,可以满足1Cr11Mo Ni W1VNb N钢渗层深度≥0.25 mm、表面维氏硬度739~840 HV的技术要求。     

非调质钢表面硬化处理工艺

试验用非调质钢为F35MnV、F38MnVS、F40MnVS、F45MnVS及F49MnVS铁素体-珠光体钢和F12Mn2VBS贝氏体钢。对这些钢进行了表面硬化处理试验。结果表明,铁素体-珠光体型非调质钢可采用气体渗氮、离子渗氮和气体氮碳共渗以提高其表面硬度和耐磨性,但贝氏体非调质钢氮碳共渗处理后,其冲击韧度从46.7 J降低到了35.0 J,故不宜采用该工艺进行表面硬化。此外,F40MnVS钢的高频感应淬硬层表面硬度和硬化层深度与45钢的基本相同,经渗氮处理的F35MnV和F40MnVS钢渗层的化合物层比40Cr、45和38CrMoAlA钢的薄,而扩散层较厚者厚,表面硬度比40Cr、45钢高,比38CrMoAlA钢低。经气体氮碳共渗的非调质钢具有良好的综合力学性能。     

SKD11钢的气体热渗铬工艺和性能

采用热反应扩散沉积法(TRD)对有无预渗氮处理的SKD11钢试样分别以950、900、850、800和750℃进行气体热渗铬。利用SEM和EDS测量铬原子扩散深度;根据经典动力学理论计算活化能及扩散系数;利用XRD分析相结构;再进行维氏硬度测量和耐磨实验。结果表明,经渗氮前处理的渗铬试样在各温度下铬原子扩散深度比未经渗氮均有增加,有预渗氮渗铬层最深达到20μm,未经渗氮渗铬层只有13μm,其活化能分别为106.09和147.47 k J/mol,表面硬度分别为1610及1760 HV。在各实验温度下,经渗氮预处理渗铬试样的耐磨性均比未经渗氮试样好,渗铬温度高于850℃耐磨性优于基材,低于850℃硬度虽然高于基材,但耐磨性不及基材。在较高温度(950和900℃)渗铬时,有渗氮预处理试样的渗铬层结构为Cr2C和Cr2N相,无渗氮预处理为Cr2C相;在较低温度(800和750℃)渗铬时,有渗氮预处理试样的渗铬层结构为Cr7C3和Cr N相,无渗氮预处理为Cr7C3相。     

复合化学热处理对G13Cr4Mo4Ni4V钢组织和硬度的影响

采用扫描电镜、洛氏硬度计和维氏显微硬度计研究了渗氮140 h对渗碳+淬火+回火G13Cr4Mo4Ni4V钢微观组织及硬度的影响。结果表明,渗碳+淬火+回火后G13Cr4Mo4Ni4V钢有效渗碳层深度为1.45 mm,渗碳层最高硬度为785 HV,心部硬度为420 HV,经渗氮处理后有效渗碳+渗氮层深度降为1.34 mm,渗氮层深度为0.22 mm,渗氮层最高硬度可达到948 HV,心部硬度为451 HV,较未渗氮试样硬度略有提高。渗碳+淬火+回火和添加渗氮处理后G13Cr4Mo4Ni4V钢的表面洛氏硬度相当,均在62~65 HRC 之间,但渗氮处理后试样的硬度波动性较大。添加140 h渗氮的渗碳+淬火+回火后G13Cr4Mo4Ni4V钢实现了“表面硬心部韧”的目标,渗氮层深度满足工程需要,但添加渗氮处理后G13Cr4Mo4Ni4V钢在渗碳层和渗氮层出现类网状碳化物,因此在渗氮过程中需要综合考虑渗氮层深度和微观组织,以获得良好的综合力学性能。     

30CrNi3钢的稀土催渗研究

对30CrNi3钢进行了稀土氮碳共渗及气体氮化试验,并与常规渗氮结果进行了对比。利用金相显微镜、显微硬度计对渗氮层深度、表面硬度进行检测并分析。结果表明:稀土催渗不仅可以加快渗氮速度,提高耐磨性,而且可以显著提高渗氮层深度及表面硬度。     

不锈钢表面低温气体渗氮层组织结构及合金元素对其的影响

采用低温气体渗氮工艺对1Cr17和1Cr17Ni2不锈钢进行表面改性处理.利用光学显微镜、X射线衍射分析(XRD)、X光电子谱分析仪(XPS)、显微硬度计等研究了不同工艺下渗氮层的组织结构和硬度,获得渗层增长动力学曲线,分析合金元素对渗层组织结构和渗层增长的影响.结果 表明:采用低温气体渗氮处理可在不锈钢表面形成一定厚度的致密且完整的改性层,不锈钢表面硬度显著提升.渗氮层主要由含氮“膨胀”α相(αN)和F％-3N相组成.Ni元素有利于含氮“膨胀”α相的形成和渗层厚度的增加以及渗层硬度的提高.     

38CrMoAlA、40Cr钢经不同渗氮工艺处理后的性能研究

研究了38CrMoAlA和40Cr钢经气体渗氮、气体氮碳共渗、离子渗氮处理后渗氮层的组织、硬度、摩擦磨损和腐蚀性能。试验结果表明，38CrMoAlA钢渗氮层的硬度及在3．5％NaCl溶液中的耐蚀性能高于40Cr钢，但抗摩擦磨损性能不如40Cr钢。依气体渗氮、气体氮碳共渗到离子渗氮的顺序，渗氮层的抗磨损性能逐次提高，但抗腐蚀能力逐次降低。从钢的化学成分、渗氮层的硬度和韧性出发，对38CrMoAlA和40Cr钢渗氮层的性能差异进行了分析与总结。     

关于烧结钢的离子氮化

通过对两三种烧结钢进行离子氮化处理,研究了烧结密度和添加的合金元素对其氮化特性的影响,得到下面的结果: (1)在表面生成的化合物层组织为ε—Fe_(2-3)N和γ′—Fe_4N两相。 (2)对于纯铁系试样,烧结密度越高,氮的表面扩散系数D值越大,氮化时获得的化合物层和扩散层厚度就越深。含Cu、Cr元素的合金系试样都比纯铁系试样的化合物层深,而扩散层浅。 (3)烧结密度对表面硬度的影响较大,试样的密度越大,表面硬度越高。含Cr的试样,离子氮化后,表面硬度明显上升,可达HV600以上。     

40Cr钢表面激光合金化及其在螺杆强化中的应用

在40Cr钢表面进行Co/W合金、超细WC(2～3 μm)两种材料激光合金化的试验,检验了合金化层的组织和性能,通过与气体渗氮层的比较,表明激光合金化可以得到晶粒细化,稀释率低,与基体结合牢固的表面强化层.合金层的显微硬度、耐磨损等性能比气体渗氮有不同程度的提高.40Cr钢的注塑机螺杆经激光合金化强化后使用寿命比气体渗氮提高了两倍,显示了良好的应用前景.     

0Cr17Ni4Cu4Nb钢气体渗氮工艺

对0Cr17Ni4Cu4Nb钢在固溶和固溶+时效两种状态下进行两种不同的渗氮工艺试验,探讨了工艺温度、氨分解率、原始组织对该材料渗层深度、渗氮后组织和性能的影响。结果表明:经固溶后是否时效,0Cr17Ni4Cu4Nb钢渗氮后得到的渗氮层深度、表面硬度及心部硬度基本相同,可考虑采用固溶后直接渗氮;540℃渗氮后的性能优于480℃渗氮后的性能。     

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。     

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.     

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.     

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.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.