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Materials
Published in Jonathan Hetreed, Ann Ross, Charlotte Baden-Powell, Architect's Pocket Book, 2017
Jonathan Hetreed, Ann Ross, Charlotte Baden-Powell
Ground gas protection against radon, methane, carbon dioxide and hydrocarbons is provided by sheet membranes and cavity barriers as required under Building Regulations. Site radon levels need to be checked prior to detailed DPM design; simple checks are available online. Checks will indicate one of three radon levels and the protection required: none; basic protection; full protection. Basic protection can be provided simply by connecting carefully sealed DPMs to perimeter DPCs via cavity trays. Full protection requires sub-floor venting with the potential of passive stack or fan-assisted ventilation. For ground bearing floors, the vent duct is connected to a central vent sump – effective to a radius of approximately 15 m or for an area of 250 m2.
Effect of FSW process on anisotropic of titanium alloy T-joint
Published in Materials and Manufacturing Processes, 2022
Yu Su, Wenya Li, Fuyang Gao, Achilles Vairis
All welds were produced with a commercial machine (type FSW-RL31-010, Beijing FSW Technology Co, Ltd, of China). The rolling direction was selected to welding direction for sheet materials, and W-25Re alloy was the material of the FSW tool. During the welding, the probe was set at an angle of 2.5°. The tool was tapered with a diameter of 9 mm at the root and 4 mm at the tip, the probe length of 3.7 mm and shoulder diameter of 18 mm. During the welding, argon gas was used as gas protection to prevent the oxidation of the joint. The welding speed was set to 50 mm/min, and the rotation speeds used were 650rpm and 850rpm. In every experiment, the plunge depth remained unchanged at 0.2 mm. The Vickers hardness tester (Struers Duramin-A300, Denmark) was used for microhardness measurements at 500 g and 15s. The EBSD tests were used to study the recrystallization degree and texture distribution of the joint, which were performed and analyzed on a scanning electron microscope (SEM) (TESCAN MIRA3 XMU) with the EBSD data acquisition software (HKL-Channel 5, Oxford). Before EBSD, the specimens were mechanically polished and electropolished at 25 V in 20°C for 40s in an electrolyte of 6 vol.% of perchloric acid, 30 vol.% of n-butyl alcohol and 64 vol.% of methyl alcohol.
A novel perception toward welding of stainless steel by activated TIG welding: a review
Published in Materials and Manufacturing Processes, 2021
Dipali Pandya, Amarish Badgujar, Nilesh Ghetiya
During welding, an arc is formed between the electrode and weld metal due to the ionization of the gas. Arc length generally varies from 1 mm to 10 mm111. Increasing the arc length and resistance to the flow of charged particles leads to higher voltage at a constant value of current.[71] When the arc length increases, the heat distribution area at the anode root becomes wider. Because of the wider arc of plasma in TIG welding, aerodynamic drag force increases, which makes the weld pool wider.[91] Increasing the arc length also reduces the overall arc efficiency because of an increase in the anode root area. Heat loss from the weld pool surface increases due to the more convection and radiation from the weld pool surface. Mills and Keene[92] observed that increasing the arc length reduces the d/w ratio as shown in Fig. 11. At higher arc length, thinner shielding gas protection to the weld pool becomes weak. It allows carbon dioxide to enter the outer layer of shielding gas and enhance the arc oxidizability. In this situation, surface-tension-induced convection becomes weaker due to oxide formed on the weld surface, and thus d/w ratio is adversely affected104. Initially, with increasing arc length, the weld voltage increases which dominates the effect of anode root area, oxidizability of arc and heat loss from the plasma arc. But after reaching the optimal arc length, the above three parameters dominate the effect of weld voltage and form a wider and shallow weld pool.
A novel crucible-less inert gas atomisation method of producing titanium powder for additive manufacturing
Published in Powder Metallurgy, 2019
Mingyue Zheng, Shaoming Zhang, Qiang Hu, Jun Xu, Weimin Mao, Liangliang Lu, Huijun He, Yingjie Liu, Wendong Zhao
Titanium wire as a raw material requires a low oxygen content (≤500 ppm) and a low impurity content. The nozzle system is the core part of gas atomisation technology, and its structure and performance determine the level of atomisation efficiency, atomisation process stability and the performance of titanium powder. It consists of a main atomising gas nozzle (pressure is P0) and an auxiliary shielding gas spout (pressure is P1). A continuous feeding device is required for uniform and stable supply of raw titanium wire, and it plays the role of straightening the titanium wire. A high-frequency induction heating system is applied to melt the titanium wire. The function of the cooling water system is to adjust the temperature of the atomisation tower in order to protect the atomisation tower. The high-pressure gas can contain inert gas, which is mainly used to provide high-pressure atomisation gas and gas protection for the entire atomisation system. The pressure inside the tower is regulated by the vacuum equipment system. Before atomisation, the vacuum equipment system draws out the air from the tower. During the atomiation process, the vacuum equipment system takes the atomising gas out of the atomisation chamber. The atomised metal powder will eventually be collected in the powder container system. The powder container system is generally composed of two parts, one of which is installed below the atomisation chamber to collect large size powders and the other is installed below the cyclone to collect small size powder.