热处理节能与环保

文中扼要介绍了热处理的“零保温工艺”、“非调质钢工艺”、低碳马氏体强化工艺和扩大感应加热表面热处理工艺等,使热处理加工工艺达到节能效果。结合热处理生产现状,对治理和防止热处理环境污染,提出些看法。     

铝部件流化床热处理技术

流化床热处理工艺能够明显减少热处理时间,提高热处理工艺的稳定性。由Arizotah公司开发的流化床热处理工艺能够使生产企业将热处理在线系统并入铸造和锻件生产流程中。     

反应堆压力容器终接环缝焊后局部热处理工艺

简要介绍了压水堆核电厂反应堆压力容器热处理工艺,说明了反应堆压力容器终接环缝整体热处理的弊端,阐述了终接环缝局部消应力热处理工艺方案和工艺实施等,分析了局部热处理的优、缺点,旨在为同类设备确定热处理工艺提供参考。     

热处理工艺对重载齿轮用20CrNi2Mo钢性能的影响

针对重载齿轮用20CrNi2Mo钢热处理后易产生变形的问题,研究了热处理工艺对20CrNi2Mo钢性能的影响。结果表明:采用改进后的热处理工艺,试样的伸长率、断面收缩率、冲击韧度与原始工艺相比变化不大,抗拉强度、表面硬度、热处理畸变量均比用原始热处理工艺处理的性能要好,因此重载齿轮用20CrNi2Mo钢热处理时应采用改进后的热处理工艺代替原始工艺,为扩大20CrNi2Mo钢应用领域奠定了基础。     

模具钢常用热处理工艺规范的选择

模具钢常用热处理有退火、正火、淬火和回火,其工艺都是由加热、保温和冷却3个阶段所组成。在热处理生产中,往往由于热处理工艺控制不当,使工件产生某些缺陷,对热处理件的质量影响很大。常用热处理工艺规范的选择国家标准有明确规定。本文根据最新国家标准,对常用热处理工艺规范的选择进行介绍,其目的在于使用者能合理地选用热处理工艺;更好地理解、宣传和贯彻现行标准。     

热处理工艺系统的研制

本文介绍了我们研制的热处理工艺系统的软件总体结构、工艺设计、回火温度的计算以及工艺库、热处理基础数据库的建立。实现了工艺设计、工艺管理的现代化。改变了热处理工艺工作者的工作模式,是计算机在热处理行业中应用的重要组成部分。     

铝部件流化床热处理技术

流化床热处理工艺能够明显减少热处理时间,提高热处理工艺的稳定性。由Arizotah公司开发的流化床热处理工艺能够使生产企业将热处理在线系统并入铸造和锻件生产流程中。[编者按]     

航空结构件热处理CAPP系统中的工艺决策

从热处理质量检验与控制、航空热处理工艺参数以及热处理辅助工序等方面,分析了基于航空标准和生产实践经验的热处理工艺决策,为航空结构件热处理CAPP系统提供理论基础.     

高性能机械零部件的复合热处理

随着制造业的持续发展,对机械零件的性能要求也越来越严格,单一的热处理工艺已不适用于高性能要求的零件,需采用复合热处理工艺,即由两种或多种热处理工艺,热处理与相关工艺按功能继承和优质经济的原则组合的工艺。目前应用的复合热处理工艺有:①多种热处理方法复合;②涂(镀)覆与热处理复合;③形变热处理;④整体或表面强化与表面形变强化复合。简述了下列复合热工艺的应用实例:节能降耗的复合热处理,渗氮或氮碳共渗后淬火,化学热处理与淬火回火复合,渗氮或氮碳共渗与氧化处理复合,表面改性与热处理复合,以及强韧化处理的复合,等。     

高碳铬钢轴承的热处理

轴承是基础件之一,其使用寿命在很大程度上决定于热处理质量。影响轴承热处理质量的主要因素有原材料的冶金质量、锻造工艺、预备热处理、热处理设备、热处理工艺及淬火介质等。介绍了高碳铬钢轴承的预备热处理、控制气氛加热炉等热处理设备和热处理工艺等内容。     

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.     

Dynamic Compaction of Pure Copper Powder Using Pulsed Magnetic Force

The compaction of pure Cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

PRECIPITATION SELECTIVITY AND GROWTH OF PEROVSKITE PHASE FROM TITANIUM BEARING BLAST FURNACE SLAG

The effects of transformation of slag composition and additive agents on the morphology, the precipitation behavior, the crystal growth, and the volume fraction (VF) of perovskite (CaO·¤TiO_2) crystal in the Ti-bearing blast furnace slags were investigated. As the morphology of perovskite is dispersed in molten slags, the crystal growth mechanism of the melting of fine dendrites and the coarsening of large grains exist throughout the solidification of molten slags. With the increase of CaO and Fe_2O_3 content, VF of perovskite obviously increases. However, high basicity leads to the viscosity of slag, which results in the reduction of the average equivalent diameter (AED). The experimental results showed that the presence of the additives CaF_2 and MnO efficiently decreased the viscosity of the slags, and obviously improved the morphology of perovskite and promoted its growth.     

The Seepage Characteristics of Heterogeneous Body With Different Spreading Solution Modes and its Applications

As the dump was a typically heterogeneous body, the seepage was different with varied spreading solution modes. The phenomenon of lamination that occured in the site was simulated using three layers in an indoor experiment, and the seepage effect comparison experiment of the inside spreading solution model and the top spreading solution model have been carried out. In the inside spreading solution mode, the phreatic planar flew without infiltration and the parallel layer motion model was used to calculate the seepage coefficient and equivalent seepage coefficient of each state respectively. In the top spreading solution model, the phreatic planar flew with an even infiltration on the surface, and the vertical layer motion model was adopted to calculate the above coefficient. The results showed that the seepage coefficient of the inside model was larger than the top model in the heterogeneous body, The ratio of them was between 1.42 and 3.07. On the basis of these results, the following new technologies were discussed: installing a few small diameter mechanical pore sand piles with every lamination in the using dump; drilling some holes one-off in the unused dump. These two methods could changed the top spreading solution into the inside model, thus the seepage in the dump was improved.     

Study on Properties of Pulse Electrodeposited RE-Ni-W-P-SiC Composite Coatings

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.     

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.     

Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass

This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle.     

冲压圆点连接机理初探

对冲压圆点连接的机理和圆点处的金相组织进行了分析。冲压圆点连接可分为4个阶段 ,即板料初压入阶段、冲压圆点成形初期阶段、冲压圆点形成阶段、保压阶段。由于被连接的板料在冲压连接圆点处受挤压 ,所以在材料的连接处产生压应力 ,提高了连接的抗疲劳强度。此外 ,对冲压圆点连接的特点、应用范围及影响因素进行了论述     

薄板冲裁工艺方法研究

探讨了薄料冲裁的主要工艺方法.基于薄板冲裁间隙小、模具制造难度大、对冲压设备要求苛刻的基本工艺问题,将目前常用的薄板冲裁工艺方法归纳为四大类,即聚氨酯橡胶冲裁法、辊压冲裁法、拉应力冲裁法、小间隙冲裁法等.阐述了这4种工艺的冲裁机理、模具结构、特点及适用场合等,对实践中薄板冲裁工艺方法的选择具有借鉴作用.