Abstract: To provide a galvanized steel sheet having high strength, specifically, a tensile strength of 1,150 MPa or more, and excellent resistance spot weldability, a base steel sheet has a defined chemical composition, an amount of diffusible hydrogen in the base steel sheet is 0.20 mass ppm or less, and surface roughness Ra of the galvanized steel sheet is 0.6 ?m or less.

Abstract: To provide a galvanized steel sheet having high strength; specifically, with a tensile strength of 1160 MPa or more and excellent resistance spot weldability. A chemical composition of a base steel sheet contains one or more of Ti, Nb, V, and Zr: 0.02% or more and 0.20% or less in total, and an amount of diffusible hydrogen in a zinc or zinc alloy coating layer is 0.40 mass ppm or less.

Abstract: A method for treating the interior surfaces of holes as well as the surfaces of a perforated workpiece by dipping it into treating liquid includes a step of causing treating liquid to flow at both ends of the holes in a direction perpendicular to these holes at different velocities. In order to create these liquid flows at different velocities, the workpiece is dipped in the liquid so that the holes extend substantially horizontally, and air bubble jets are alternately delivered along both ends of the holes, or fins are provided at locations adjacent both ends of the holes so as to extend outwardly upwardly at one side of the hole ends and extend outwardly downwardly at the other side of the hole ends, and these fins are moved upwardly and downwardly.