Methods for determination of residual stress in rail

The residual stresses in rails are generated during the manufacturing process and have uneven distribution in rail cross section. The residual stress is a part of basic tensile stress in rail foot. For used rail, the residual stress value of 80 MPa is commonly used in the engineering calculations. On the other hand, the standard EN 13674 prescribes residual stress values up to 250 MPa and destructive method using electrical strain gauge for measurement of rail residual stress. Since destructive measurement methods are unsuitable for use in the track, the possible non-destructive in situ methods for measuring of residual stresses in the rails are discussed in this paper. The fundamentals of X-ray diffraction, ultrasonic, magnetic and electromagnetic methods are explained, as well as, their advantages and disadvantages