| Relationship between microstructure of pearlitic rail steels and mechanical properties, and the effects of alloying elements are subject, which people have always been studying. This paper is devoted to the study of CrNb new rail steels compositions and microstructure and mechanical properties, and effect of chrome and niobium additions on microstructure and mechanical properties and weld properties of as roll and heat treatment rail steels. By properties comparison of CrNb rail steels and PD3, BNbRE, understanding effecting of alloying elements on rails steels. The principal results are as follows:1.The mechanical property were achieved with as roll CrNb (0.75%C) rail steel: Gb-l O65MPa, 6~=1 0.5%, ak(20C) =1 3.3J/cm2,K1c(-20 t)33.OMPam?, the pearlite interlamellar spacing is to 0.1895pm, seven grade size of austenite grain is determined. After heat treating (0.75%C) , u~= 1265MPa, 6514.5%, ak(20扖)=16.72J/cm2, the pearlite interlamellar spacing is to 0.09965pm, the 9?0 grade size of austenite were achieved.2.The best cool velocity of CrNb rail steel heat treating is within the range I .OCIs?1.75CIs, the best heating temperature is within the range 80041C-850, after welding, rail is required to cool slowly or heat treating.3.Except of improving strength, Chrome additions can make CCT diagram moving towards right. Niobium additions can diminish the size of austenite grain of hot-roll and heat treatment rail steels, improve toughness.4.The strength and toughness of as roll and heat treating CrNb P03 BNbRE is at the same level.
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