PD_3和PD_3RE重轨钢的性能、组织等分布形貌及内耗

Internal Friction and Profile of Property and Structure of PD_3 and PD_3RE Rail Steels

对PD3和中间包加少量稀土的PD3RE重轨钢的连铸坯和产品轨进行了硬度和组织的Profile观测。发现加稀土减小钢坯硬度分布的波动幅度,有效减消280 mm×380 mm连铸坯心部的低性能区(在PD3RE铸坯上甚至未测出低硬度区);在仅含0.016%P的PD3钢坯里观测到Fe-P(C)共晶组织,而加稀土可完全抑制这种组织;还发现,PD3RE钢轨表层区出现很明显的硬化,这种硬化是珠光体细化引起的。测量轨腰样品的内耗表明,加稀土除了减小轨腰的内应力和增加铁素体中的固溶C之外,还增强了钢轨表层的渗氮倾向。

The profile of both hardness and microstructure of continuous casting blanks and rails of PD3 heavy rail steel and PD3RE steel containing small amount of rare earth （RE） added from tundish were studied. It is found that the addition of RE makes the fluctuation of the hardness value decrease, and inhibits effectively and/or even removes lower hardness value（zone） in the centric area of the blank with a cross section of 280 mm × 380 mm, and that the surface layer in the rail head of PD3RE steel is obviously hardened and the reason causing this hardening is due to the thinning of the pearlite structure. The metallographic observation shows that there exists a Fe-P（C） eutectic structure in the blank center of the PD3 steel containing only 0. 016% P, while the addition of RE can fully inhibit this structure. The internal friction measured on the specimens of the rail waist indicates that besides decreasing internal stress in the rail waist and increasing content of solution carbon in ferrite, the addition of RE also enhances nitriability of surface layer of the rail.