| 摘要 |
Provided are a high-strength hot-pressing member and a method for producing the same. A material is obtained by subjecting a cold-rolled steel sheet having a composition containing, in mass%, C in the amount of at least 0.090% and less than 0.30% and Mn in the amount of at least 3.5% and less than 11.0%, to a treatment comprising maintained heat in a temperature region of at least the Ac1 transformation temperature and no higher than 850°C for at least 100 seconds and no more than 48 hours, followed by cooling. In addition, a hot-pressing member having a prescribed shape is obtained by subjecting the material to a heating step for maintaining a temperature in the range of 800-1,000°C for 600 seconds or less, and a hot-pressing molding step for simultaneously press molding using a molding die and tempering. As a result, it is possible to obtain a high-strength hot-pressing member having a composition containing 3.0% or more of a retained austenitic phase, with the remainder constituting a martensitic phase, and exhibiting the tensile properties of a tensile strength TS of 1500 MPa or higher and a uniform elongation uEl of 6.0% or higher. Using a steel sheet having a Zn-plating layer or an Al-plating layer on the surface thereof as the cold-rolled steel sheet to be used also imparts the effect of suppressing the formation of scaling on the member surface and improving the producibility of the hot-pressing member. |
