Galvanized steel sheets, components, and methods for manufacturing them.

Abstract

DEPCT6915 / 01 / 2569 To provide techniques for producing galvanized steel sheets with a high yield ratio and capability. It exhibits high bending and high hydrogen brittleness resistance, with a TS of 980 megapascals. Or more and less than 1470 megapascals. Galvanized steel sheets have a steel microstructure with the following characteristics: In terms of area fractions, ferrite: less than 50%, martensite and bainite: all 50% or Furthermore, with 10% or less austenite remaining, martensite contains carbides. Average grain size of 50 nanometers or more, and 200 nanometers or less, 75% or Furthermore, the TM1 / TM2 ratio of the fraction by the area of ​​TM1 of the rehydrated martensite. The entire microstructure in the area extends from the surface to 1 / 8 of the sheet thickness per fraction. The TM2 region of the martensite is rehydrated across the entire microstructure in the 1 / 8 region. Up to 3 / 8 of the thickness of the sheet is 0.70 or more, and which has a galvanized layer on the surface. Of the above, the galvanized steel sheet has a TS980 megapascal or higher and less. 1470 megapascals and a yield ratio of 0.60 or more, and the amount of hydrogen that can be diffused. It is 0.45 parts per million by mass or less;