Abstract: A composite metal tubing is provided which includes an inner tubular member press fitted into the bore of an outer tubular member. The inner tubular member is made of a steel having a tensile strength of at least 48 kg/mm.sup.2. Additionally, the wall of the inner tubular member has a thickness equal to 1.5 to 8.5% of the outer diameter of the outer tubular member. The resultant composite tubing has increased pressure resistance and resists cavitation.

Abstract: A tapered fuel injection pipe with a collar pressed and fitted below the neck is provided with a fine slit between the inside surface of the collar and the outside surface of a tapered part of the injection pipe in the free end zone of the collar.By providing such fine slit, the strength against breakage is remarkably improved.

Abstract: A high pressure fuel injection tubing material and a method of manufacturing the same wherein the inside surface of a fine diameter thick wall metal tube made of a single steel material is cemented, then the entire metal tube is heated and then immediately the outside surface is quenched or the inside surface is quickly heated and is then left to naturally cool so that the carbon content may gradually increase with the hardness distribution toward the inside surface from the outside surface of the wall thickness and a residual stress producing part in the peripheral direction may be formed.The above mentioned injection tubing material is high in the pressure resistance and can be well guaranteed against cracking and breaking by vibrations or the like.

Abstract: A method of brazing a stainless steel with a stainless steel or another metal wherein, in brazing the stainless steel with a stainless steel or another metal, the stainless steel side of both opposed jointing parts is plated with copper, then a copper base-tin alloy of a melting point of 850.degree. to 1081.degree. C. is used as a brazing material and said brazing material is heated together with the jointing parts to a temperature lower than the melting point of copper in a nonoxidizing gas atmosphere such that the brazing material may be melted at said temperature.The brazed stainless steels are cooled by being quickly passed through a temperature range of 850.degree. to 600.degree. C. The bonding force of the resulting stainless steels is much higher than heretofore obtained.

Abstract: This invention is made with a view to increasing the fusing strength of an end piece in a valve moving push rod for internal combustion engines. The fusing part of the push rod according to the present invention consists of an .alpha.-martensite structure and a primary truestite structure in a cotransition boundary range of a segmental section formed into the hardened layer of the end piece from the fused boundary surface of the end piece with a tube end part and is provided with a tough mixed layer arcuated from the inside end part of the above mentioned fused boundary surface to the outside end part thereof. This mixed layer is obtained by reducing by a heat feeding means a quick temperature drop caused by the fusing part simultaneously with cutting off the fusing current in welding by electric resistance the end piece on the fixed side surface to the peripheral edge of the end port of a tube material.

Abstract: This invention is made with a view to remarkably improving the smoothness of the inside surface of the hole of a high pressure fuel injection pipe to be used for Diesel internal combustion engines and to improving the true circularity of the hole shape and the uniformity of the hole diameter and is a method of manufacturing high pressure fuel injection pipe materials characterized by forming a pipe body by cutting and removing an interposed slag layer collected and deposited near the center of a steel bar material in the steel bar direction and then gradually elongating the pipe body to be of desired dimensions by the repetition of an annealing treatment in a non-oxidizing or reducing atmosphere and a drawing and reducing treatment by using both die and plug.

Abstract: An anticorrosive overlapped coating so far practiced as applied to such iron and steel materials as plates, pipes, bars or wires is formed by electroplating an iron or steel material on the surface with an Sn base - Zn alloy layer and applying a chromate-treatment on it. However, this requires such long time in forming a plated layer thickness that a reduction of the plating time together with a further improvement of the anticorrosion is hoped for today. The present invention has succeeded in making it possible to reduce the plating time while improving the anticorrosion and in improving the productivity by forming an electroplated layer of an Sn base - Zn alloy directly or through an electroplated layer of Zn on the surface of a steel material, then forming an electroplated layer of Zn on the electroplated layer of said alloy and further applying a chromate-treatment on said Zn layer.

Abstract: A noise is generated unavoidably owing to hunting phenomenon that appears in process of increasing or decreasing torque to be transmitted by a hydraulic coupling in a hitherto known type, when it is subjected to change of the ambient temperature.A purpose of this invention is to provide a new and unique hydraulic coupling which enables hydraulic connection to be effected very quickly in such a way that engagement or disengagement between ferrite and magnet is applied to transfer mechanism in hydraulic coupling, depending on the ambient temperature.The above purpose of the invetion has been accomplished as follows.Magnetical attractive force between ferrite and magnet is predetermined to overcome spring force in a normal temperature, and working temperature for this new mechanism according to the invention is selected around at Curie temperature of said ferrite material.