عنوان مقاله [English]
Steel wheels are affected during coach operation on the rail due to high normal and tangential stresses. The wheel profile is then varied, which could be resulted in an unexpected derailment when wheel wear is focused on within the flange region. This dangerous situation should be prevented, using various solutions including the deployment of higher grades of steel wheels. A field test was planned and conducted within 2007-2008 period to find out the influence of B5T grade steel on the wheel wear magnitude and pattern, which could lead to safe operation of a passenger coach. The test coach wheels were measured frequently at Tehran station for a 5-month time interval. It was found that B5T grade has a better strength to resist against wheel failure mechanisms, i.e., wear as well as rolling contact fatigue (rcf) in comparison with B2N grade which was tested during 2003-2004 period in the same route, that was Tehran-Mianeh track. The wear pattern was gained more symmetric within each wheelset (about 25%) than the previously used wheelsets within field test results. Consequently, this coach likely operated longer life (40%), as well as, safer than the earlier test coach which had been equipped with B2N grade steel wheels. To justify the higher wear rate at the initiation of coach operation, it could be explained when the running-in period of wheels was finished, a harder material raised to the wheel surface resulted in a balanced material removal condition in terms of wear. As a result, the wear rate of the wheels was gradually decreased.