Modifying residual stress levels in rail flash-butt welds using localised rapid post-weld heat treatment and accelerated cooling

被引：1

作者：

Tawfik, D. ^{[1
]}

Mutton, P.J. ^{[2
]}

Chiu, W.K. ^{[3
]}

机构：

[1] Advanced Materials Group, AECOM Ltd, Melbourne

[2] Institute of Railway Technology, Department of Mechanical Engineering, Monash University, Melbourne, VIC

[3] Department of Mechanical Engineering, Monash University, Melbourne, VIC

来源：

International Heat Treatment and Surface Engineering | 2008年 / 2卷 / 3-4期

关键词：

Continuously welded rails; Flash-butt welding; Modelling; Post-weld heat treatment; Residual stresses; Stress relief;

D O I：

10.1179/174951508X429212

中图分类号：

学科分类号：

摘要：

Flash-butt welding is used in the manufacture of continuously-welded rails. Finished welds typically exhibit high tensile residual stresses in the rail web and at the upper surface of the rail foot, which may increase the risk of fatigue failure in service. An understanding of the influence of the welding process, including post-weld cooling, on the residual stress distribution is necessary to improve the performance of flash-butt welds by post-weld heat treatment (PWHT), since incorrect treatment may have adverse effects on both residual stress and weld material characteristics. A finite element model has been developed to simulate post-weld cooling in flashbutt welded AS60 kg m -1 rail. Computed thermal histories for normal (air) cooling, rapid PWHT, and accelerated cooling (water spray) were used as inputs to calculate sequentially coupled stress-time histories, including phase transformations. In addition, the localised influence of the initiation time for rapid PWHT, after final upset, on the reduction of tensile residual stresses was investigated. Heating the rail foot immediately after final upset reduced tensile residual stresses in the web region of the weld. Preliminary numerical predictions showed that water quenching the entire weld region too soon after the austenite-pearlite transformation is completed can induce further tensile residual stresses without affecting the microstructure. The results of the numerical analysis can be used to modify the flash-butt welding procedure to lower residual stress levels, and hence improve weld performance. © 2008 IHTSE Partnership Published by Maney on behalf of the Partnership.

引用

页码：126 / 130

页数：4

共 11 条

[1]

Tawfik D., Residual stress behaviour in normal cooled and rapid post-weld heat treated rail flash-butt welds, (2006)

[2]

Moller R., Mutton P., Steinhorst M., Improving the performance of aluminothermic rail welding, Proc. 7th Int. Heavy Haul Conf, pp. 331-338, (2001)

[3]

Marich S., Vines M., Baggott M., Examination of big dipper rail failures initiated at flash butt welds, Proc. Symp. on 'Railroad welding, pp. 130-152, (1983)

[4]

Carpenter G.F., Sonon D.E., Residual stresses in welded rails, Proc. Symp. on 'Rail road welding, pp. 153-160, (1983)

[5]

Mutton P.J., Alvarez E.F., Failure modes in aluminothermic rail welds under high axle load conditions, Eng. Fail. Anal, 11, 2, pp. 151-166, (2004)

[6]

Beretta S., Boniardi M., Carboni M., Desimone H., Mode II fatigue failures at rail butt-welds, Eng. Fail. Anal, 12, 1, pp. 157-165, (2005)

[7]

Tawfik D., Mutton P.J., Chiu W.K., Residual stress behaviour due to localised, rapid post-weld heat treatment in flash butt welded rails, Proc. Conf. on 'Railway engineering, pp. 341-350, (2006)

[8]

Cope G.H., British railway track design, construction, and maintenance, England, The Permanent Way Institution, (1993)

[9]

Tawfik D., Mutton P.J., Chiu W.K., Transient thermal stress analysis on rapid post weld heat treatments applied to flash butt welded rails, J. Sci. Technol. Weld. Join, 11, 3, pp. 326-336, (2006)

[10]

Fischer F.D., Hinteregger E., Rammerstorfer F.G., Study on the residual stresses in railroad rails after cooling down from the rolling temperature, Proc. Symp. on 'Applied mechanics rail transportation, 96, pp. 37-43, (1988)

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