| Experimental study is performed on the fatigue and fracture properties of D1wheel steel for high speed train. Tensile tests of mechanical properties, fatigue tests on durability and S-N relations, impact tensile tests on fracture toughness and fatigue crack growth tests on threshold values are carried respectively out to rim, web or gub material of the wheel. Following conclusions can be reached:(1) Probabilistic mechanical properties were measured respectively using normal distribution for the rim, web and hub materials. Toughness characteristics of tensile fracture were observed on the fracture surfaces of test specimens by SEM.(2) Probabilistic fatigue strength of durability is measured using the maximum likelihood method proposed by Zhao-Yang and then probabilistic S-N curves including super-long life regime are determined using the extensive method with a principle of concurrent proabability at the transition point from mid-short life to super-long life regime. Comparing analysis of the curves for D1steel and the R7T steel coded by EN13262reveals that the present D1steel holds a better fatigue capacity.(3) Probabilistic fracture toughness values are measured using normal distribution for the rim, web and hub materials of D1steel. Physical failure characteristics were observed using SEM.(4) Threshold values of fatigue crack growth (FCG) for the wheel rim, web and hub materials were obtained using a derived method of the local relation for FCG rate-stress intensity factor range. Probabilistic measurement is performed using normal distribution to describe threshold data. Physical characteristics of the fatigue crack growth are revealed by SEM.The present study provides the foundation for investigations on the fatigue reliability analysis of wheel and crack safety.The present work was supported by the National Natural Science Foundation of China (NSFC, Grant No. U1334204), Research Foundation from the National Railway Ministry of China (Grant No.2009J015,2013J008-C). |
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