Abstract: A ferritic-austenitic two-phase stainless steel consisting essentially of, in wt. %, over 0% to not more than 0.05% of C, 0.1 to 2.0% of Si, 0.1 to 2.0 of Mn, 20.0 to 23.0% of Cr, 3.0 to 3.9% of Ni, 0.5 to 1.4% of Mo, over 0% to not more than 2.0% of Cu and 0.05 to 0.2% of N, the steel further containing, when desired, at least one element selected from the group consisting of over 0% to not more than 0.5% of Ti, over 0% to not more than 0.5% of Nb, over 0% to not more than 1.0% of V, over 0% to not more than 0.5% of Al, over 0% to not more than 0.5% of Zr, over 0% to not more than 0.5% of B, over 0% to not more than 0.2% of a rare-earth element, over 0% to not more than 1.0% of Co, over 0% to not more than 1.0% of Ta and over 0% to not more than 1.0% of Bi, the balance being substantially Fe. Cr, Mo and N are within the range defined by the following expression [i]: Cr+3.

Abstract: An Ni3Al-base heat-resistant alloy containing, in % by weight, 6.0 to 9.0% of Al, 2.0 to 15.0% of Cr and 0.5 to 3.0% of Zr, the balance being Ni and inevitable impurities, the alloy having a metal structure comprising Ni3Al as the main phase thereof. When required, the alloy may further contain over 0% to not more than 5.0% of W, over 0% to not more than 3.0% of Mo, over 0% to not more than 3.0% of Nb, over 0% to not more than 0.003% of B, over 0% to not more than 0.3% of C and 0.003 to 0.03% of N, wherein the combined amount of W, Mo and Nb is up to 5.0% if at least two of these elements are present.

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.