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:
In a stainless steel flux cored wire comprising a stainless steel shell and a flux filling the shell, the amount of Si contained in the entire wire is 2.5% by mass or higher, preferably 3.0% by mass or higher in terms of SiO 2 , and the amount of at least one compound selected from the group consisting of polytetrafluoroethylene, graphite fluoride and perfluoropolyether contained in the flux is 0.005 to 0.10% by mass of the total mass of the wire in terms of F, preferably 0.020% by mass or higher. By employing such a constitution, in welding of Cr-Ni-based and Cr-based stainless steels and other materials, fume generation and hexavalent chromium leaching can be significantly reduced, and excellent welding workability can be provided.
Abstract:
PROBLEM TO BE SOLVED: To provide an aluminum alloy heat exchanger with high corrosion resistance, achieving further weight and cost reduction, especially suitable as a heat exchanger for an automobile by using a refrigerant passage pipe made of an aluminum alloy excellent in strength after brazing and corrosion resistance, having improved extrudability.SOLUTION: The aluminum alloy heat exchanger is heated and brazed in an atmosphere furnace after applying a coating material obtained by adding a binder to a mixture made of compound-based flux powder containing Si powder and Zn to the surface of the refrigerant passage pipe, and attaching a bare fin made of an Al-Mn-Zn-based alloy. The refrigerant passage pipe is formed of an aluminum alloy extruded material containing 0.5-1.7% of Mn, Cu limited below 0.10%, Si limited below 0.10%, and the balance Al with inevitable impurities. In the mixture, the mixing ratio of the compound-based flux powder containing the Si powder and Zn falls within the range of 10:90-40:60. The binder is added so that it amounts to 5-40% of the entire coating material, and applied to the outer surface of the refrigerant passage pipe so that the total amount of the compound-based flux powder containing the Si powder and Zn becomes 5-30g/m. The potential of the surface of the refrigerant passage pipe after heating for brazing is baser than that of a region deeper than the diffusion depth of the Si and Zn, and the potential difference is 20-200 mV. Moreover, the potential of the fin is baser than that of the deep part of the refrigerant passage pipe.