Abstract: The present invention is a production method of a hot-dip galvanized steel sheet including annealing a belt-shaped steel sheet having a Si content of greater than or equal to 0.2% by mass, wherein the annealing is continuously carried out using an annealing furnace having an oxidation heating zone and a reduction heating zone in this order, while the steel sheet is fed using rollers. The annealing includes oxidizing a surface of the steel sheet in the oxidation heating zone at a temperature at which roll pickup does not occur and reducing an iron oxide layer, formed by the oxidizing, in the reduction heating zone before the iron oxide layer reaches an initial roller in the reduction heating zone.

Abstract: The present invention is a production method of a hot-dip galvanized steel sheet including annealing a belt-shaped steel sheet having a Si content of greater than or equal to 0.2% by mass, wherein the annealing is continuously carried out using an annealing furnace having an oxidation heating zone and a reduction heating zone in this order, while the steel sheet is fed using rollers. The annealing includes oxidizing a surface of the steel sheet in the oxidation heating zone at a temperature at which roll pickup does not occur and reducing an iron oxide layer, formed by the oxidizing, in the reduction heating zone before the iron oxide layer reaches an initial roller in the reduction heating zone.

Abstract: Steel-sheet continuous annealing equipment includes, in sequence, a pre-heating zone, a heating zone, a soaking zone, a cooling zone, a reheating zone, an overaging zone, and a final cooling zone, and further includes a rapid heating region and a rapid cooling region that are provided within a range from the reheating zone to the final cooling zone (including the reheating zone and the final cooling zone), the rapid heating region allowing rapid heating of a steel sheet at a heating rate of 15° C./s or more and the rapid cooling region allowing rapid cooling, at a cooling rate of 10° C./s or more, of the steel sheet that has been rapidly heated in the rapid heating region. Various steel-sheet products ranging from mild steel sheets to ultrahigh-tensile steel sheets can be produced by performing a heat treatment with such steel-sheet continuous annealing equipment.

Abstract: Steel-sheet continuous annealing equipment includes, in sequence, a pre-heating zone, a heating zone, a soaking zone, a cooling zone, a reheating zone, an overaging zone, and a final cooling zone, and further includes a rapid heating region and a rapid cooling region that are provided within a range from the reheating zone to the final cooling zone (including the reheating zone and the final cooling zone), the rapid heating region allowing rapid heating of a steel sheet at a heating rate of 15° C./s or more and the rapid cooling region allowing rapid cooling, at a cooling rate of 10° C./s or more, of the steel sheet that has been rapidly heated in the rapid heating region. Various steel-sheet products ranging from mild steel sheets to ultrahigh-tensile steel sheets can be produced by performing a heat treatment with such steel-sheet continuous annealing equipment.