Abstract:
PROBLEM TO BE SOLVED: To provide an abrasion resistant welded steel pipe that can be produced with high productivity at a low cost without decreasing its weld crack resistance, and a method of producing the same.SOLUTION: The abrasion resistant welded steel pipe excellent in weld crack resistance, is characterized in that the base material thereof and weld metal each comprise specific chemical components each in a specific amount, the Vickers hardness (Hv) of the base material of the welded steel pipe is Hv 150 to 250, that of the weld metal is Hv 230 to 350, and that of a weld heat affected zone is Hv 150 to 350, and the dispersion density of a sulfide comprising at least one selected from Fe, Mn and Ti each having an aspect ratio of at least 5 in the weld metal is not greater than 10 pieces/mm.
Abstract:
PROBLEM TO BE SOLVED: To provide a welded structure and a welding method capable of preventing a delamination crack.SOLUTION: In the welded structure in which a weld layer is formed in a first base material composed of low alloy steel, the weld layer includes a first build-up weld layer 33 composed of low alloy steel or carbon steel with its carbon content smaller than that of low alloy steel, and layered on the base material 31, a second build-up weld layer 34 composed of a 600-type nickel-based alloy and layered on the first build-up weld layer 33, and a third build-up weld layer 35 composed of a 690-type nickel-based alloy and layered on the second build-up weld layer 34.
Abstract:
PROBLEM TO BE SOLVED: To provide a seamless bend pipe with the pipe end having the same inner diameter as that of a straight pipe for a line pipe while eliminating the need for the thickness of the seamless bend pipe to be greater than required and the need for the pipe end of the seamless bend pipe to be internally ground after manufactured, and also to provide a welded joint between the seamless bend pipe and the seamless straight pipe. SOLUTION: The seamless bend pipe comprises a bend part, and straight pipe parts at both ends, wherein the inner diameter of each pipe end is greater than the inner diameter of the bend part. The inner diameter of the pipe end is enlarged with cold pipe enlarging work. Cold diameter shrinking work may be done before the cold pipe enlarging work. The welded joint provided by welding and joining the seamless bend pipe to the seamless straight pipe with the pipe end having the same inner diameter as the pipe end thereof. COPYRIGHT: (C)2009,JPO&INPIT