Research and Development > JFE TECHNICAL REPORT > No.15 Special Issue on “Steel Bar and Wire Rod” > Shear Reinforcement Possessing both of Over 1275 MPa Yield Strength and High Ductility after Welding

No.15 Special Issue on “Steel Bar and Wire Rod”

Shear Reinforcement Possessing both of Over 1275 MPa Yield Strength and High Ductility after Welding

IWAMOTO Takashi      YAMAUCHI Akira      SAKASHITA Mikio

Abstract

JFE Steel has developed the high strength shearing reinforcement that reduced the softening induced by heat during welding. The purpose of reducing the softening is to prevent the deformation concentration on the softened area. Softening by the heat effect was the maximum when the steel was heated up to 700–750°C. The most softened area corresponds to the area heated up to the highest temperature where austenite does not exist in the microstructure. Hardness in the heat-affected zone is raised with the increase of the amount of Mo, V. When the difference in Vickers hardness between the most softened area and the base steel is 70 or less, it breaks at the base steel, which has high ductility, even after welding. High strength has been united to excellent ductility by controlling the hardness distribution in the heat-affected zone after welding.

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