Threaded Seamless Steel Pipe, Cold Drawn Within Trial

Today the work-temperature and pressure parameter of boiler fire-electricity has greatly been improved, in order to use live of water-cooling mural of canister, passing-heat effect of pipe mural should be effectively improved, water-cooling pipe mural no longer use common round pipe on second-critical and exceed-critical boiler, instead use cool-drawn rifled seamless tube. Cool-drawn rifled seamless tube is a sort of seamless tube with spirality rib inside manufactured by cool-drawing. It picks ASME steel-grade such as SA210-1, SA-210C as it's material.This article introduce the try-manufacture of rifled seamless tubeφ60.3×7.5 SA-210C, which adopting hot-rolling and cool drawn technology.Billet is produced by the process of EBT (electric steelmaking) + LF (secondary steelmaking processes) + VD (vacuum degassing) + HCC (horizontal continuous casting) which can reduce the content of gas such as H, O, and N , change lard shape and improve hot stability and intensity.Hot rolling must control size precision and surface quality of hollow. Cool drawn process adopt two-way drawing, distortion quantity should be suit. Size of hollow and finished tubes adjacence to assure size precision of finished tubes. Select rational process parameter of acid-wash and lubrication and rational lubricant to reduce attrition resistance, improve use live of inside and outside model and improve inside-surface quality. Inside-die 30°screw rise angle and 30°-55°opening angle, can prevent inside-wall of pipe be scraped by inside screw thread rib side and figuration distortion.Logical heat treatment system can reduce distortion resist force when drawing. Anneal temperature of semi-finished articles is 800- 850 centigrade, time is 20-30 minute, cool manner is air-cooling. The heat treatment of finished product is carried through according to ASME SA-210C pressure boiler finished pipe. The normalizing temperature is 900±10 centigrade, heating time is 30 minute. By researching for technology of cool drawn rifled seamless tube, author think that finished tubes can satisfy with the request of ASME SA210/SA210M steel-grade and client. It can be manufactured as correlation parts of electricity boiler with high parameter 30 ten thousand KW or 60 ten thousand KW.