| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a tailored blank material of different materials having excellent press forming performance by controlling the ratio between the work hardening characteristic value of the material on the side having high tensile strength in a tailored blank material on which plural stock sheets different in tensile strength have continuously been welded and controlling the work hardening characteristic value of the material on the side having low tensile strength to a specified range. SOLUTION: The ratio (n1/n2) between the work hardening characteristic value (n1) of the material on the side having high tensile strength and the work hardening characteristic value (n2) of the material on the side having low tensile strength is controlled to 0.75 to 3.8. Preferably, the stock sheet is composed of a steel sheet or a surface treated steel sheet, and the tensile strength of the steel sheet on the side having low tensile strength is controlled to 380 to <590 MPa, and the ratio (n1/n2) in the work hardening characteristic value is controlled to 1.0 to 3.8. The stock sheet to be used is a cold rolled steel sheet, a plated steel sheet of zinc, or the like, a stainless steel sheet, a thin sheet of nonferrous metal such as aluminum. As the welding method, any of a laser welding method, a mash seam welding method, an arc welding method, an electron beam welding method and a TIG welding method is adopted. It effectively works also to the fractured form of stress rate-determining.</p> |
