Influence of additive materials on the roughness of AISI D2 steel in electrical discharge machining (EDM) environment

The quality of the machined surface resulted from the electrical discharge machining (EDM) environment is not efficient according to the previous studies. One of the significant problems is the impedance of dielectric fluid, where it is contributing to focusing the plasma channel in a limited area. Hence, this behavior leads to appearing deep craters on the machined zone. The researchers have attempted to enhance the average of surface roughness by employing powder particles or surfactant as the additive materials in the dielectric fluid. Unfortunately, these studies did not present a comparison between these additive materials in this environment. Therefore, the present study aims to compare the performance of the average of surface roughness (R_a) for AISI D2 steel by utilizing Nano chromium powder (NCP) and Span-20. The present work has proved that the behavior of the average of surface roughness for this steel is dropping at the maximum level of Nano chromium powder concentration and pulse duration as compared to the behavior with the Span-20. Moreover, the best roughness was produced by this steel with Nano chromium powder at 2 g/L and 20 μs for this powder and the pulse duration.     

Konzept zur Verbesserung der Meerwasserbeständigkeit von Wälzlagerstahl

To develop corrosion‐resistant hardenable bearing steels for seawater applications the contents of Mo and Cr were raised in respect to X65Cr14 and the carbon content was lowered by making use of the soluble N content. The steels X51CrN(14)14 and X51CrMoN(14)15‐3, to be molten under normal pressure, and steel X33CrMoN(32)15‐3, to be processed under an N₂ pressure of = 4.7 bar, promise a higher resistance to pitting corrosion and a lower liability of coarse eutectic carbides in segregated areas without discernible disadvantages in respect to hardness and retained austenite. The study has led to a pre‐selection of promising new steels just by thermodynamic calculations and empirical equations without time‐consuming and costly experiments.     

Einfluss der Schleifbehandlung auf das Korrosionsverhalten von Chrom‐Nickel‐Stählen

The influence of grinding treatment of stainless steels on the corrosion behaviour Mechanical grinding of stainless steels is often used for decoration purposes, for instance in the interior decoration. However, this treatment can cause problems regarding the corrosion resistance. During investigations of the influences of processing parameters of industrial grinding it was shown, that roughness only is not the expected crucial parameter for the corrosion resistance. The variation of different grinding parameters and also the type of abrasives have a substantial influence. Beside the long term tests electrochemical investigation at the ground surfaces are presented. The different corrosion susceptibility of the surfaces could be proven by means of electrochemical noise measurements.     

Status quo und Trends der Galvanotechnik

Status quo and trends in electroplating Electroplating is still one of the most commonly applied surface refinement processes. Besides the automotive industry, one of the largest acceptor of electroplating surfaces, the domain electrical engineering and electronics, construction, engineering, aviation and aerospace technology, the jewellery industry and the medical‐technology (e.g. dental prosthetics) are responsible for the high turnover and development. Constantly rising commodity prices, stricter legal regulations (e.g. EU end‐of‐life vehicle directive), growing demand profiles of the customers in terms of quality and functionality, and increasing environmental awareness always lead to new challenges. By means of this process innovation is created. This paper gives an overview on the status quo of electroplating. In addition, selected current trends are presented.     

The study of microstructure and properties of chromium bronze for contact shoe

The microstructure and properties of chromium bronze, with different chromium content and treatment method, were characterized by using scanning electron microscope, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy and optical microscopy technique. For the specimens with the same treatment method, with increasing of the chromium content, the number of chromium phase increase and the dispersion strengthen effect enhances. On the other hand, the hinder effect on the electrons enhances and the electrical conductivity decreases. For the specimens with same component, the tensile strength and hardness order from low to high are: casting, aging treatment and solution aging. The electrical conductivity order from low to high are: casting, solution aging and aging treatment.     

Zum Einfluss des Schweißens auf das Kriechverhalten moderner Stähle für die thermische Energieerzeugung

The influence of welding on creep behaviour of modern steels for thermal power generation Un‐ and low alloyed ferritic/bainitic Chromium steels as well as high alloyed ferritic/martensitic 9–12 % Chromium steels are widely used for high temperature components in thermal power generation. Welding in all its variety is the major repair and joining technology for such components. The weld thermal cycle has significant influence on the base material microstructure and its properties. The Heat Affected Zone is often regarded as the weakest link during high temperature service. While weldments of un‐ and low alloyed ferritic Chromium steels can show significant susceptibility to Reheat Cracking in the coarse grained heat affected zone, weldments of high alloyed ferritic Chromium steels generally fail by Type IV Cracking in the fine grained heat affected zone during long term service. In this paper the influence of the weld thermal cycle on the base material microstructure is described. Long‐term creep behaviour of weldments is directly related to the main failure mechanisms in creep exposed ferritic weldments and implications for industries using heat resistant ferritic steels are shown.     

Numerical study on the effect of the thermo‐mechanical properties of alloys on the behaviour of super plastic forming tools

The paper describes a numerical study to investigate the effect of the thermo‐mechanical properties of heat resisting nickel and chromium alloys, used for super plastic forming (SPF) tools, on the tool service behaviour. The purpose of the paper is to rank the relative importance of each property studied for the heat resisting class of cast nickel and chromium alloys, subjected to repeated thermal cycles under typical industrial super plastic forming conditions. A finite element model of a tool block within an industrial press furnace was developed to simulate the typical thermal cycles of an super plastic forming tool, and predict the resulting mechanical performance. Important thermal and mechanical properties were identified for the cast nickel and chromium class of alloys studied in this paper and suitable ranges for the properties were determined for numerical simulations. The results include a quantitative analysis of the effect of the properties studied.     

Schweißzusatzwerkstoffe können/müssen nicht immer die Anforderungen der Grundwerkstoffe erfüllen

Weld metal as strong as base metal? The development of new steels is always a challenge for the manufacturer of filler metals. In many cases it is obvious that some properties of the base metal cannot be fulfilled with matching filler metals. In some cases, dissimilar filler metals can solve the problem in some cases, there is no chance to meet the requirements of the base metal (for example yield strengths of new ultra high strength steels). This paper deals with different kinds of new steels and the requirements for the weld metal with examples from motor car industry (Mangan Austenite), crane (Ultra high strength steels), earthmoving machinery (Wear‐resistant steels) and offshore (Supermartensitic steels). Specific problems will be discussed and best solutions will be highlighted. These examples make clear that the success of new kinds of steels in the market depends on solving the joining problems of these steels.     

GC-126PDD氦离子化气相色谱仪分析COS杂质的应用试验

羰基硫(化学式:COS),可替代溴甲烷和磷化氢而被用作熏蒸剂。有机合成中,用于合成硫代酸、取代噻唑、杀虫剂巴丹、除草剂燕麦敌、杀草丹等。石化工业中用作在线仪表的校正气、标准气。