爆炸焊接炸药中添加剂的应用比较

为解决爆炸焊接过程中,工业盐添加剂对植被影响及炸药爆炸产生的噪音、振动危害对周边环境的影响,在乳化炸药中添加碳酸钙来取代工业盐,以充当爆速及密度调节的作用。通过实验最终确定性能比较稳定的低爆速的混合炸药,该炸药可以降低噪音及爆破振动,适用于爆炸焊接,消除了工业盐对爆炸焊接场地周边环境的影响,增大爆炸焊接场地的生产能力,降低了生产成本,具有较好的推广应用前景。     

爆炸焊接专用炸药的研究与应用

为满足金属爆炸焊接的要求,以岩石膨化硝铵炸药为主体,配以适量的添加剂制得一种爆炸焊接专用炸药.试验结果表明:通过改变添加剂的含量,可以得到不同爆速的爆炸焊接炸药,爆炸焊接效果理想,且该炸药具有优良的安全性能和可靠的爆炸性能.     

爆炸焊接专用炸药的研究与应用

为满足金属爆炸焊接的要求,以岩石膨化硝铵炸药为主体,配以适量的添加剂制得一种爆炸焊接专用炸药。试验结果表明:通过改变添加剂的含量,可以得到不同爆速的爆炸焊接炸药,爆炸焊接效果理想,且该炸药具有优良的安全性能和可靠的爆炸性能。     

粉状乳化炸药在爆炸焊接中的应用研究

论述了爆炸焊接对炸药的性能要求和粉状乳化炸药在爆炸焊接中的应用。研究如何优化粉状乳化炸药的配方来达到爆炸复合的需求,并阐述了粉状乳化炸药在爆炸复合市场的应用前景。     

爆炸焊接专用炸药实验研究

以2#岩石硝铵炸药为主体,通过加入一定比例的食盐、膨胀珍珠岩配制成爆速可调的SE型爆炸焊接专用炸药,其加工方便、成本较低,最低爆速为2048m/s。经铜-钢爆炸焊接实验表明,该炸药具有爆速低、爆轰稳定、能量适中特点,较好地避免了猛炸药焊接时所出现的问题。研究、开发爆速更低、能够适应管状物体焊接需要的可塑性炸药,是有待进一步研究的课题。     

爆炸焊接专用炸药实验研究

以2#岩石硝铵炸药为主体,通过加入一定比例的食盐、膨胀珍珠岩配制成爆速可调的SE型爆炸焊接专用炸药,其加工方便、成本较低,最低爆速为2048m/s。经铜-钢爆炸焊接实验表明,该炸药具有爆速低、爆轰稳定、能量适中特点,较好地避免了猛炸药焊接时所出现的问题。研究、开发爆速更低、能够适应管状物体焊接需要的可塑性炸药,是有待进一步研究的课题。     

爆炸焊接对炸药性能要求的探讨

为了保证爆炸焊接复合板达到良好的质量和能否在爆炸焊接中使用非理想爆轰炸药,对所使用的炸药性能进行了探讨。结合爆炸焊"窗口"理论以及工程实例对用于爆炸焊接的炸药爆速、密度、爆轰状态等参数进行计算,得到了爆炸焊接中炸药爆速的上、下限,密度的取值范围以及提高炸药能量利用率的途径,并在铝-钢焊接工程中取得了较好的效果,以期对爆炸焊接工作有所裨益。     

一种平板状爆炸焊接用炸药

将硝酸铵、硝酸钠、尿素、水、机油和Span80等通过乳化技术制备出乳胶基质。将制备好的乳胶基质和泡沫树脂混合,得到一种平板状炸药。实验表明:该种炸药的密度可低至0.17g/cm³,爆轰的临界厚度为18 mm,在最低临界密度下的爆速为1 678 m/s;随着密度的增加,爆速增加。密度为0.23 g/cm³时,测得爆速为2 149 m/s。初步分析,该炸药可满足某些爆炸焊接工艺的要求。     

爆炸焊接用炸药的研究

本文叙述的是如何利用普通的高级炸药RDX、TNT,经钝感处理后降低其爆速,使之成为爆炸焊接工艺中能够应用的低爆速炸药的实验研究。测试了这种混合炸药在不同钝感剂比例、不同直径、不同厚度下的爆速,以及在使用状态下的临界直径和临界厚度。文中还给出了这种低爆速混合炸药的工程计算方法。     

爆炸焊接条件下炸药爆速的探针法测定

用探针法测量了几种混合炸药的爆速 ,绘制了它们沿爆轰方向的分布曲线 ,分析和讨论了试验结果。指出 ,炸药的爆轰和它的传播 (爆速 )有一个发生、发展、持续和消亡的过程 ,研究这个过程对于爆炸焊接来说有重要的理论和实际意义     

Study on mechanism and dynamics of inert powder explosion inhibitor inhibiting aluminum powder explosion

In order to study the suppression performance and action mechanism of inert powder on aluminum powder explosion flame, using the dust explosion flame propagation test system, five kinds of common inert powder and two kinds of aluminum dust with different particle sizes were selected for explosion flame suppression and overpressure suppression experiments. Combined with the thermal characteristic curve of inert powder, the inhibition performance and action mechanism of inert powder on aluminum powder explosion were systematically studied. The results show that the inhibition effect of MPP dry powder on aluminum dust is better than that of NaHCO₃, CaCO₃, Al(OH)₃ and NH₄H₂PO₄; The inhibition mechanism model of inert powder on aluminum powder explosion flame is established, and the action mechanism is analyzed. The oxidation process of aluminum dust with and without MPP dry powder was analyzed by Coats Redfern (C-R) method, and the activation energy and kinetic models of different stages were obtained. The results were verified by Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) methods. The research results can provide a theoretical basis and basis for the explosion suppression design of aluminum dust and the development of explosion suppression powder.     

Feedstock powder processing research needs for additive manufacturing development

Additive manufacturing (AM) promises to redesign traditional manufacturing by enabling the ultimate in agility for rapid component design changes in commercial products and for fabricating complex integrated parts. By significantly increasing quality and yield of metallic alloy powders, the pace for design, development, and deployment of the most promising AM approaches can be greatly accelerated, resulting in rapid commercialization of these advanced manufacturing methods. By successful completion of a critical suite of processing research tasks that are intended to greatly enhance gas atomized powder quality and the precision and efficiency of powder production, researchers can help promote continued rapid growth of AM. Other powder-based or spray-based advanced manufacturing methods could also benefit from these research outcomes, promoting the next wave of sustainable manufacturing technologies for conventional and advanced materials.     

The effect of recycling on the oxygen distribution in Ti-6Al-4V powder for additive manufacturing

Abstract

Ti-6Al-4V powder has been recycled 30 times in an electron beam melting system. A combination of electron microscopy techniques has been used to show that the recycled powder has a 35% higher oxygen content, and that the particles have a more irregular morphology, a narrower particle size distribution, and a much more variable microstructure than the virgin powder. The microstructures in the recycled powder particles vary from a martensitic α′ structure, which is identical to that in the virgin powder, to a two-phase α + β structure. This variability is related to the complex thermal history of the unmelted metal powder in the system. Despite these differences, all of the particles exhibit essentially the same surface oxide thickness; the excess oxygen in the recycled powders is instead located in the β phase. The possible consequences for the structure and properties of the resultant additively manufactured parts are discussed.     

铜/不锈钢加筋板爆炸焊接工艺实验

随着我国核电新能源的发展,新型材料的需求也在不断的增加,铜/不锈钢加筋板是其中一种,具有重要工程应用价值,目前无法用常规的冷、热加工工艺进行生产。通过爆炸焊接法,采用一种新的"凸台式"装药形式,在支撑模板设计及其填充方案、工装等方面进行了深入研究,优化了焊接参数,并对成品的结合界面进行了剪切强度测试、金相观测、电镜扫描和显微硬度测试。检测结果表明:铜/不锈钢焊接结合面为波状冶金结合界面,在波峰两侧存在含金属氧化物的"冠状"漩涡,结合界面附近的晶粒被拉长变细,显微硬度显著升高,界面结合强度超过铜材。     

铜/不锈钢加筋板爆炸焊接工艺实验

随着我国核电新能源的发展,新型材料的需求也在不断的增加,铜/不锈钢加筋板是其中一种,具有重要工程应用价值,目前无法用常规的冷、热加工工艺进行生产。通过爆炸焊接法,采用一种新的"凸台式"装药形式,在支撑模板设计及其填充方案、工装等方面进行了深入研究,优化了焊接参数,并对成品的结合界面进行了剪切强度测试、金相观测、电镜扫描和显微硬度测试。检测结果表明:铜/不锈钢焊接结合面为波状冶金结合界面,在波峰两侧存在含金属氧化物的"冠状"漩涡,结合界面附近的晶粒被拉长变细,显微硬度显著升高,界面结合强度超过铜材。     

Numerical simulation of explosive welding using the material point method

Explosive welding involves detonation of explosive, interactions of fluid-structure and plastic deformations of metal plates at the instant of the explosion. Conventional mesh-based methods such as the finite element method (FEM) and finite difference method (FDM), are limited in simulation of the explosive welding when mesh distortion and interaction of different materials occur. In order to describe process of the explosive welding and accurately predict physical parameters for the explosive welding, numerical simulation of the explosive welding which involves multi-physical phenomenon is performed by using material point method (MPM). Not only can major physical phenomena of explosion impact be well captured, but also some important technical parameters for the explosive welding can be attained based on the MPM simulation. Through the comparison with the experimental results, it is shown that the MPM is a robust tool in simulation of the explosive welding.     

Defects and anomalies in powder bed fusion metal additive manufacturing

Metal additive manufacturing is a disruptive technology that is revolutionizing the manufacturing industry. Despite its unrivaled capability for directly fabricating metal parts with complex geometries, the wide realization of the technology is currently limited by microstructural defects and anomalies, which could significantly degrade the structural integrity and service performance of the product. Accurate detection, characterization, and prediction of these defects and anomalies have an important and immediate impact in manufacturing fully-dense and defect-free builds. This review seeks to elucidate common defects/anomalies and their formation mechanisms in powder bed fusion additive manufacturing processes. They could arise from raw materials, processing conditions, and post-processing. While defects/anomalies in laser welding have been studied extensively, their formation and evolution remain unclear. Additionally, the existence of powder in powder bed fusion techniques may generate new types of defects, e.g., porosity transferring from powder to builds. Practical strategies to mitigate defects are also addressed through fundamental understanding of their formation. Such explorations enable the validation and calibration of models and ease the process qualification without costly trial-and-error experimentation.     

Powder bed fusion additive layer manufacturing of titanium alloys

Powder bed fusion (PBF) techniques for additive layer manufacturing (ALM) are reviewed with a focus on titanium alloys production. Selective laser melting and electron beam melting are discussed in terms of feedstock production and processing-microstructure relationships. To control the PBF processes, an outline is presented on the computational modelling approaches for simulating process parameters and defects such as residual stresses and porosity at different length scales. It is concluded that by improving powder production techniques, designing new alloys and further developing ALM hardware, PBF techniques can reach commercial maturity.

This review was submitted as part of the 2019 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.