PROBLEM TO BE SOLVED: To provide a welding steel pipe capable of restraining the occurrence of a processing crack even if a pipe is expanded in the high pipe expansion ratio such as 70% or more.SOLUTION: A welding steel pipe 1 of the present invention is composed of steel in a base material, and includes a bead-cut welding part 2. The base material includes a heat-affected part 3 adjacent to the welding part 2 and a base material part 4 positioned on the outside of the heat-affected part 3. When assuming the product of a plate thickness (unit mm) and Vickers hardness (unit HV) measured in the heat-affected part 3 and the base material part 4, as rupture strength in its measurement position, an evaluation value (F) of dividing the total sum of the product (ΔF×0.3) of multiplying a difference (ΔF) between rupture strength (Fs) of the welding part 2 and the heat-affected part 3 and rupture strength (Fm) of the base material part 4 by 0.3 mm, by a distance (D) in the pipe circumferential direction in the welding part 2 and the heat-affected part 3, is 0 to 25. The welding steel pipe 1 is suitably used as a feed oil pipe of expanding a pipe of one end 1A by 70% or more than the other end 1B.SELECTED DRAWING: Figure 1
【課題】70%以上という高い拡管率で拡管しても加工割れが生じるのを抑えることの可能な溶接鋼管を提供する。【解決手段】本発明の溶接鋼管1は、母材が鋼からなり、ビードカットされた溶接部2を含む。そして、母材は、溶接部2に隣接する熱影響部3と、熱影響部3の外側に位置する母材部4とを含む。溶接部2、熱影響部3及び母材部4において測定された板厚(単位mm)とビッカース硬さ(単位HV)との積をその測定位置での破壊強度であるとしたとき、溶接部2及び熱影響部3の破壊強度(Fs)と母材部4の破壊強度(Fm)との差(ΔF)に0.3mmを掛けた積(ΔF×0.3)の総和を、溶接部2および熱影響部3における管周方向の距離(D)で除した評価値(F)は、0以上25未満である。溶接鋼管1は、一端1Aが他端1Bに比べて70%以上拡管された給油管として好適に用いられる。【選択図】図1
WELDING STEEL PIPE AND FEED OIL PIPE
溶接鋼管及び給油管
2017-09-28
Patent
Electronic Resource
Japanese
IPC: | B23K Löten , SOLDERING OR UNSOLDERING / B21D WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL , Bearbeiten oder Verarbeiten von Blechen, Metallrohren, -stangen oder -profilen ohne wesentliches Abtragen des Werkstoffs / B60K Anordnung oder Einbau von Antriebseinheiten oder von Kraft- bzw. Drehmomentübertragungen in Fahrzeugen , ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES |