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Yamamoto R.,Rail Welding Laboratory | Terashita Y.,Rail Welding Laboratory | Tatsumi M.,Rail Welding Laboratory | Itoh H.,Rail Welding Laboratory | Umenai K.,East Japan Railway Company Former RTRI
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2016

In Japan, four welding processes have been generally adopted for producing continuous welded rail (CWR): flash welding (FW), gas pressure welding (GPW), enclosed arc welding (EAW), and thermit welding (TW). Thermit welding method is the most popular rail welding process in Japan. The reliability of the thermit welds is high, because the failure rate has only been about 0.004 % over the last 10 years in Japan. However, recently there have been many cases where thermit welds are judged to be defective due to surface defects. Surface defects are often observed when welding new and worn rails. Welding test results show that surface defects are caused by gas generated from the contact of luting sand with molten steel which enters gaps between the welding mold and rail surface. © 2016, Ken-yusha Inc. All rights reserved.


Yamamoto R.I.,Rail Welding Laboratory | Tatsumi M.,Rail Welding Laboratory | Itoh H.,Rail Welding Laboratory | Terashita Y.,Rail Welding Laboratory | Yoshida Y.,Iwatani Corporation
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

Gas pressure welding (GPW) is a solid phase welding method. This method is commonly used for rail welding in Japan. However, there is concern that the supply of acetylene gas, which is used as the fuel gas in the conventional GPW system, will cease due to the recent tendency of reduction of demand. Moreover, a large volume of CO2 gas is generated in the GPW process since acetylene gas is a hydrocarbon. Therefore, a new GPW method of welding rails by mixed gas of hydrogen and ethylene gas was developed in order to ensure continued use of GPW in the future. This paper describes this newly developed GPW method.


Ito H.,Rail Welding Laboratory | Terashita Y.,Rail Welding Laboratory | Tatsumi M.,Rail Welding Laboratory | Yamamoto R.-I.,Rail Welding Laboratory | Shitara H.,Rail Welding Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2010

Although improvements in ultrasonic inspection methods have brought about a reduction in the incidence of alumino-thermic weld failure, some failures still occur in the early stages after installation of weld as a result of solidification cracks. It is considered that such cracks arise from rail movement in the longitudinal direction just before the weld metal solidifies. However, the details of the related occurrence conditions are not yet clear. In this study, the occurrence conditions of solidification cracking and preventive methods for weld failures caused by such cracking were discussed based on simulative testing of solidification cracks. As a result, the occurrence conditions were clarified, and preventive methods and detective methods for solidification cracks were suggested.

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