China. Product Description. China Supply GB Steel Crane Rail. Material: U71MN, 50MN, Q235B. Rail size: P18, P22, P24, P30, P38, P43, P50, Qu70, QU80, QU100, QU120. Introduction and application. Steel rail, also called rail track, steel track, is the main component of railway track. Its function is to guide the wheels of the locomotive, bear the