Abstract: A heat and corrosion resistant steel pipe having multi-layered coating comprising a steel pipe, a Zn—Ni alloy plating layer deposited to the outer surface of the steel pipe and a polyvinyl fluoride layer formed on the Zn—Ni alloy plating layer with an epoxy resin therebetween as an intermediate layer. A metal plating layer comprising Zn—Ni plating layer and Ni-plating layer may be used instead of the Zn—Ni plating layer. A chromate layer may be formed on the metal plating layer.

Abstract: A heat and corrosion resistant steel pipe having multi-layered coating comprising a steel pipe, a Zn—Ni alloy plating layer deposited to the outer surface of the steel pipe and a polyvinyl fluoride layer formed on the Zn—Ni alloy plating layer with an epoxy resin being intervened therebetween as an intermediate layer. A metal plating layer comprising Zn—Ni plating layer and Ni-plating layer may be used instead of the Zn—Ni plating layer. A chromate layer may be formed on the metal plating layer.

Abstract: The present invention has for its object to obtain a heat-resistant and anticorrosive multilayer metal-plated steel object which excels in the uniformity of high-efficiency processability and anticorrosiveness. The steel object provided by the present invention to achieve such object comprises a steel substrate, a Ni-layer plated over the surface of the steel substrate to a thickness of 0.2-10 .mu.m, a first Zn/Ni alloy layer plated over the Ni-layer to a thickness of 1-15 .mu.m from an acid bath, such as a chloride bath or sulfuric acid bath, with the Ni-content of the first layer being in the range of 2-20% by weight and a second Zn/Ni alloy layer plated over the first Zn/Ni alloy layer to a thickness of 1-10 .mu.m from an alkaline bath, with the Ni-content thereof being in the range of 2-20% by weight.

Abstract: A steel product (or copper-plated steel product) with heat-resistant, corrosion-resistant plating layers which are composed of a 0.2-10 .mu.m thick nickel plating layer formed on said steel product, a Zn-Ni alloy plating layer formed on said nickel plating layer, and a chromate film formed on said Zn-Ni alloy plating layer.

Abstract: A small thick-walled composite metal fuel injection tubing for a diesel engine, for example, is manufactured from an outer carbon steel pipe, and an inner stainless steel pipe press-fitted in the large diameter carbon steel pipe by drawing. The press-fitted mating surfaces of the inner and outer pipes are metallurgically and integrally bonded together by heat-treating. As a result, at least an inside wall surface of the inner stainless steel pipe has a diffused layer of at least one kind of metal, or an alloy of two or more kinds ,of metals in combination, selected from the group consisting of Ni, Cr, Mo, Co, Al and Cu.

Abstract: A multilayer plating showing high corrosion resistance even at elevated temperatures includes a first or undercoat layer formed from cobalt, nickel or a cobalt or nickel alloy on the surface to be protected, and a second or overcoat layer formed on the first layer from zinc or a zinc alloy. The second layer may further be chromated.