制造工艺：
Manufacturing process:
1）、双金属复合管坯采用分层离心浇铸方法制备，在液态下使两层金属溶合，做到了真正的冶金结合；
1) the bimetal composite tube blank is prepared by layered centrifugal casting method, which makes the two layers of metal melt in liquid state and achieves the true metallurgical combination;
2）、采用大吨位黑色金属挤压机（或纵轧机）将双金属复合管坯热挤压（或纵轧）成无缝钢管的生产工艺；
2) the production process of hot extrusion (or longitudinal rolling) of bimetal composite tube blank into seamless steel tube by large tonnage ferrous metal extruder (or longitudinal rolling mill);
3）、还可进一步采用高精度冷轧管机将挤压出的无缝钢管轧制成精密复合管；
3) high precision cold rolling mill can be further used to roll the extruded seamless steel pipe into precision composite pipe;