激光熔化沉积快速成形TA15钛合金电子束焊接头力学性能与组织

为了进一步探索激光熔化沉积快速成形TA15钛合金的焊接性能,通过对激光熔化沉积快速成形钛合金之间以及与普通板材TA15钛合金电子束焊接的研究,获得了电子束焊接头力学性能与显微组织。结果表明:在力学性能方面,激光熔化沉积快速成形制造TA15接头力学性能优良,焊接系数大于0.9;在组织方面,激光熔化沉积快速成形TA15之间、激光熔化沉积快速成形和板材TA15之间焊缝中心的显微组织均为网篮组织,拉伸断裂呈韧性断裂特征。     

双熔化极旁路电弧焊控制系统控制器快速原型实现

在介绍了双熔化极旁路电弧焊这种高效的焊接方法基础上,采用了基于xPC实时目标环境,建立了双熔化极旁路电弧焊实时目标的硬件平台,运用Matlab/Simulink工具开发了双熔化极旁路电弧焊控制系统的快速原型,并进行了不同控制器下的焊接特性及工艺方面的试验研究.结果表明,模糊控制器的控制效果优于九点控制器,且快速原型控制系统具有很好的快速响应性能,能较好地实现双熔化极旁路电弧焊过程稳定焊接,焊缝成形美观、飞溅小.     

沥青快速熔化技术的应用

介绍了我国炭素生产中沥青快速熔化常用的三种装置。通过对其快速熔化原理的分析，比较了三种形式的装置其对固体沥青的要求、熔化效率，装置清理、控制和日常维护等方面的差别。     

激光熔化沉积AerMet100超高强度钢凝固组织及高温稳定性

利用激光熔化沉积技术制备AerMet100超高强度钢厚板试样,利用OM、SEM和EDS研究了激光熔化沉积态组织,通过在885~1150℃范围内的高温固溶热处理研究了激光熔化沉积AerMet100钢的高温组织稳定性。结果表明,激光熔化沉积态AerMet100钢具有细小均匀、沿沉积方向定向生长的快速凝固胞状树枝晶组织,合金元素在胞晶尺寸范围内存在一定的凝固偏析,激光熔化沉积各层之间存在层间热影响区,而且AerMet100钢激光熔化沉积快速凝固胞状树枝晶组织具有异常优异的高温组织稳定性,其快速凝固胞状树枝晶特征可以保持到1100℃,原位快速凝固胞状树枝晶极低的界面能及其很弱的凝固偏析是该组织具有异常优异的高温组织稳定性的主要原因。     

快速凝固Al-Si-Cu合金钎料的组织和熔点研究

通过单辊旋铸法制备快速凝固Al-Si-Cu合金薄带钎料,并对其相组成和熔化特性进行了研究.结果表明,快速凝固试样主要由α(Al)、Si、θ(Al2Cu)三相组成,AlSi4.5Cu20Ni3RE合金试样中还存在少量AlNi相,并且试样中α(Al)均出现晶格畸变.与相同成分普通凝固试样相比,快速凝固试样的熔化温度降低,熔化区间变窄,熔化区间最大的减小幅度可达12.9%.     

铁素体基球墨铸铁激光表面重熔后的组织与性能

通过调整激光重熔工艺参数对球墨铸铁进行表面重熔处理 ,获得了白口铸铁层 ,对熔化层的显微组织、力学性能、熔化层 基体界面特性与工艺参数的关系进行了仔细研究 ,结果表明 :快速加热熔化、快速冷却凝固和部分碳被烧损 ,使熔化表面凝固后获得白口铸铁层 ,构成了球墨铸铁与白口铸铁的复合材料 ;激光重熔处理后的白口铸铁层显微组织很细 ,具有高的强度和硬度 ,随着激光束扫描速度的增大 ,显微组织变细 ,硬度增高 ;熔化层的横截面积与激光束扫描速度之间在一定条件下接近双曲线关系。     

激光熔化沉积300M超高强度钢组织与力学性能

利用激光熔化沉积快速成形工艺制备300M超高强度钢薄板试样,应用OM、SEM等方法分析了钢的组织,并测试了其室温拉伸力学性能.结果表明,由于激光熔化沉积过程中的高温度梯度及冷却速度,激光溶化沉积300M钢具有细小均匀的快速凝固胞状树枝晶,其显微组织为马氏体与贝氏体混合组织;激光熔化沉积态300M钢室温拉伸性能接近锻件水平.     

高性能航空金属结构材料及特种涂层激光熔化沉积制备与成形研究进展

介绍了近年来高性能航空金属结构材料及特种涂层激光熔化沉积制备与成形的研究进展,包括航空高性能金属结构件激光熔化沉积快速成形制造技术及应用;难熔金属材料激光约束熔化沉积制备与成形;钛合金激光表面改性及过渡金属硅化物高温耐磨耐蚀多功能涂层.     

激光熔化沉积定向快速凝固高温合金组织及性能

采用激光熔化沉积定向快速凝固工艺,制备出了具有快速定向生长微细柱晶组织的Rene95高温合金板状试样,其一次枝晶间距约为7 μm、枝晶间完全无γ/γ'共晶组织析出.结果表明,激光熔化沉积定向快速凝固微细柱晶Rene95高温合金具有优异的力学性能.     

快速凝固对Sn2．5Ag0．7Cu钎料合金熔化与铺展特性的影响

采用单辊法制备了快速凝固态Sn2.5Ag0.7Cu钎料合金薄带.通过DSC检测和铺展试验研究了快速凝固对Sn2.5Ag0.7Cu钎料合金熔化与铺展特性的影响.结果表明:快速凝固态钎料熔化区间为6℃.较常态钎料小9℃;与常态钎料相比,快速凝固态钎料能够在较低温度(260℃)、较短时间(3 min)实现速度更快、面积更大的铺展.     

钢管直缝埋弧焊焊接规范对焊缝形状的影响

在比线能量概念的基础上,探讨了直缝埋弧焊焊接规范对焊缝熔深、余高及熔宽的影响。研究表明,焊接比线能量与熔深呈线性关系变化;焊缝的余高由焊接规范与坡口形状共同决定,并可对其进行有效控制;焊接规范对熔宽影响不明显,随规范的增大有缓增趋势。同时,为了准确估算焊材消耗,提供了一个方便、快捷的经验公式。     

电冶熔铸SiC增强钢基复合材料的组织与性能

用电冶熔铸的方法制备4%SiC颗粒增强轴承钢复合材料,对其组织性能进行探索.实验结果发现:SiC颗粒在电冶熔铸工艺中发生分解,原始颗粒没有保留下来,溶入钢基体的Si和C原子在快速冷却下会发生原位反应重新生成细小的原位SiC;磨损试验发现,原位SiC的存在使基体硬度上升,复合材料的整体耐磨性比基体材料相比有明显改善,磨损机理以粘着磨损和磨粒磨损为主.     

A Comparison of Chemistry and Inclusion Distribution and Morphology Versus Melting Method of NiTi Alloys

NiTi alloys are produced by three melting methods. The first method requires compaction of nickel and titanium raw material into sections that can be joined together for melting in a Vacuum Arc Remelt unit (VAR). This ingot is melted two or more times in a VAR. The second method utilizes a Vacuum Induction Melting (VIM) unit to alloy the nickel and titanium, with the use of a graphite crucible. The resulting ingot is prepared and remelted in a VAR. The third method begins with primary melting in a vacuum Induction Skull Melter (ISM). The ISM produces ingots that are assembled into an electrode for VAR melting. For each of the melting methods, the final product depends on the quality and handling of the raw materials, the control of the process at each unit, and the preparation of the intermediate ingots for further processing. The melting method influences the final chemistry as well as the type and number of inclusions present in the final product. This study compares the chemistry and microcleanliness of product manufactured by each method to determine the appropriate melting technique that produces NiTi with the lowest residual elements, such as carbon, as well as the lowest size, and number of inclusions.     

M2O3-M′2O3系相图中间化合物熔点的计算机预报

应用原子参数－人工神经网络研究了ＭＭ′Ｏ３型的复氧化物的熔点与原子参数之间的关系,并利用已知样本集训练的人工神经网络对ＭＭ′Ｏ３型复氧化物的熔点用“留一法”进行了预报,预报结果与实测值符合较好,误差一般小于５％。研究结果表明,选择适当的原子参数－人工神经网络算法可以用于Ｍ２Ｏ３Ｍ′２Ｏ３系形成的ＭＭ′Ｏ３型复氧化物的熔点的预报。     

减少压铸件气孔的基本方法

消除压铸件气孔的方法包含4个方面：熔炼、模具、压铸参数和分型剂。其中模具因素最重要，最容易被忽视的因素是压室充满度和快慢压射转换点。文中用实例进行了讨论。     

选区激光熔化金属表面成形质量控制的研究进展

选区激光熔化是目前应用广泛的金属增材制造方法,能够实现复杂精密金属件的成形。但是,由于技术原理的限制,选区激光熔化金属表面与切削加工表面相比,成形质量仍然存在较大差距,影响了这一方法的进一步应用。如何提高表面成形质量,是目前选区激光熔化金属成形领域重要的研究方向。介绍了选区激光熔化成形原理,分析了影响选区激光熔化金属表面成形质量的因素,总结了目前选区激光熔化金属表面成形质量的控制方法及相关研究进展。指出合理地布置成形件位置、避免将成形质量要求高的轮廓面设置为第三类表面、优化扫描工艺参数,是控制和提高选区激光熔化金属表面成形质量的主要途径。     

Modeling of an aluminum melting process using constructive polynomial functions

Constantly increasing quality requirements and ever-stricter conditions pose difficult challenges for the foundry industry. They must produce the high-quality components demanded by the market at a reasonable cost. Modern technologies and innovative methods help to master this challenge. Until recently, production, from the design of the aluminum melting furnace to daily process, relied largely on traditional methods and experience. However, important data and information about the melting process—for example, the temperatures and the shape of the aluminum block in the furnace—can hardly be obtained with conventional experimental methods, as the temperatures exceed 700 °C. Therefore, this research project investigates the method of monitoring a melting process by means of optical sensors for the first time. The purpose of this paper is to predict the surface shape of the block during the melting process, as it is not possible to maintain a constant monitoring due to the heat and energy loss during measurement Behrens (Einsatz einer Lichtfeldkamera im Hochtemperaturbereich beim Schmelzvorgang von Aluminium, wt Werkstattstechnik online, 2016). To generate the necessary data, a 3D light-field camera is installed on top of an aluminum melting furnace in order to monitor the process. The basic idea is to find a general method for curve modeling from scattered range data on the aluminum surface in 3D space. By means of the (x, y, z) data from the 3D camera, the aluminum surface is modeled as a polynomial function with coefficient derived using various interpolation and approximation methods. This study presents an attempt to find the optimal polynomial function model that describes the aluminum surface during the melting process by interpolation or approximation methods. The best method for curve fitting will be extended and implemented for surface modeling. Based on this method, the melting process can be better controlled while the furnace operates continuously under stable conditions and the efficiency can therefore be increased. The proposed model can be modified for a wide variety of melting furnaces.     

高速磨削中的快速现场动平衡技术

本文研究高速高精度磨削中的快速现场动平衡技术。利用线性系统的基本理论对砂轮一主轴系统的不平衡响应进行了分析。论证了快速现场动平衡技术的基本原理并提出了一种实用的快速现场动平衡方法。平衡过程由预平衡和现场动平衡两个步骤构成。对一定安装条件的砂轮-主轴系统，通过预平衡测定不平衡量与轴承座振动幅值的比例常数及振动量相对于不平衡量的滞后角。利用测出的比例常数和滞后角，对高速磨削过程中出现的不平衡振动，可实现转子系统一次试加重的快速动平衡。可在数分钟内使转子的残余不平衡量降低至原始不平衡量的5％以下。实验表明该方法具有平衡精度高，平衡速度快，易实施的特点。     

Influence of duplex melting process on melt quality and solidification of grey cast iron

Abstract

The quality of molten iron produced by two melting processes, the medium frequency induction furnace melting process and the shortcut duplex melting process with blast and medium frequency induction furnaces, has been studied comparatively. The shortcut melting process contributes to a higher undercooling tendency of base iron, and the extent of this tendency depends on other processing parameters such as ratio of charges, fluctuation in composition, superheating temperature and holding time, etc. When the shortcut melting process is used in the production of grey cast iron, there are no essential differences, with subsequent proper inoculation, in the microstructure and mechanical properties of castings compared with the conventional medium frequency induction melting process. Inoculation is a very effective method to alleviate and/or eliminate the negative effect when the shortcut melting process is used.     

Determination of the melting rate of coated electrodes

Investigations were carried out to determine the degree of non-uniformity of the melting rate of coated electrodes as a result of preheating with passing current. The increase in the melting rate with time can be described with high accuracy by a linear dependence. The melting rate increases at the end of combustion of the electrode in comparison with the initial rate by up to 42% in comparison with the initial rate, with the average rate being up to 17.7% higher than the initial rate. A method for calculating the initial melting rate of the coated electrodes using the data on the melting rate of the electrode wire in automatic submersion-arc welding is proposed.