Abstract: Composite pipe adapted for use, for example, in line pipes for crude oil or natural gas producing oil wells and having excellent corrosion resistance and mechanical properties to withstand high temperatures and high pressures, the composite pipe having an outer layer made of a material comprising in % by weight 0.05 to 0.20% of C, up to 1.0% of Si, up to 2.0% of Mn, up to 1.0% of Cr, 0.2 to 2.0% of Ni, up to 1.0% of Mo, 0.05 to 0.15% of V, up to 0.1% of Al, and the balance inevitable impurities and Fe, the material being up to 0.45 in carbon equivalent expressed by: ##EQU1## an inner layer made of stainless steel, high alloy steel or like corrosion resistant alloy, and an intermediate layer substantially intermediate between the outer layer and the inner layer in composition and having a thickness of 10 to 100 .mu.m, the intermediate layer providing a boundary between the outer and inner layers and being metallurgically joint to the outer layer and the inner layer integrally therewith.

Abstract: A process for manufacturing a walking bar member for continuous casting from an elongated tubular metal blank by heating the blank at a temperature of 550.degree. to 1250.degree. C., subjecting the heated blank to plastic working which achieves a working ratio of up to 65% or a flattening ratio of over 1 but not greater than 3.0 to flatten the blank into a tubular body by compression over the entire length thereof, and machining a surface of the tubular body at the side thereof to be brought into contact with a slab to smooth the surface and provide a reduced wall thickness, the working ratio and the flattening ratio being represented by (D-H)/D.times.100 and W/H, respectively, wherein D is the outside diameter of the blank before the plastic working, H is the minor diameter of the tubular body after the plastic working, and W is the major diameter of the tubular body after the plastic working.