Friction Welding of Sulphur Free Machining Steel

概要

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Weldability of sulphur free machining steel in friction welding was investigated. Base metal had a diameter of 12 mm. Results are summarized as follows : (1) A suitable welding condition for sound welds in tensile test is ; Rotational speed N : 3620 rpm Heating pressure Ph : 3.0 Kgf/mm^2 Upsetting pressure Pu : 8.0-12.0 Kgf/mm^2 Heating time Th : 0.5 sec (2) In any case, an increase of heating time lowers tensile strength of weld. (3) Even the welded joint, which is made under suitable condition, has poor bending ductility. Normalizing can improve ductility of weld. However, it makes the joint liable to break at the weld in tensile test. (4) The weld made under suitable condition has an impact value of 1.3 Kgf.m/cm^2 in Charpy test using a specimen with V notch. On the whole, impact value of the weld of free machining steel is much lower than that of base metal, 3.2 Kgf.m/cm^2. (5) Fatigue strength of the weld is 29.0 Kgf/mm^2, which is lower than that of base metal by 10%. (6) When heating time is prolonged, the softened area in the weld becomes wider, and mechanical properties of weld deteriorate. (7) Mechanical properties of weld are affected by shape, size and orientation of sulphide in the heat-affected zone.
社団法人溶接学会の論文
1981-04-01