Heat-rolled steel plate for tailored rolled blank, tailored rolled blank, and methods for producing these

A heat-rolled steel plate for a tailored rolled blank comprising:

• a chemical composition consisting of, in mass %,
• C:
• 0.03 to 0.1%,
• Si:
• 1.5% or less,
• Mn:
• 1.0 to 2.5%,
• P:
• 0.1% or less,
• S:
• 0.02% or less,
• Al:
• 0.01 to 1.2%,
• N:
• 0.01% or less,
• Ti:
• 0.015 to 0.15%,
• Nb:
• 0 to 0.1%,
• Cu:
• 0 to 1%,
• Ni:
• 0 to 1%,
• Mo:
• 0 to 0.2%,
• V:
• 0 to 0.2%,
• Cr:
• 0 to 1%,
• W:
• 0 to 0.5%,
• Mg:
• 0 to 0.005%,
• Ca:
• 0 to 0.005a/o,
• rare earth metal:
• 0 to 0.1%,
• B:
• 0 to 0.005%, and
• one or more types of element selected from a group consisting of Zr, Sn, Co and Zn in a total amount of 0 to 0.05%, with the balance being Fe and impurities, and satisfying Formula (1);
• and
• a microstructure containing, in terms of area ratio, 20% or more of bainite, with 50% or more in terms of area ratio of the balance being ferrite;
• wherein:
• at a depth position that is equivalent to one-half of a plate thickness from a surface of the heat-rolled steel plate, an average value of pole densities of an orientation group {100}<011> to {223}<110> comprising crystal orientations {100}<011>, {116}<110>, {114}<110>, {113}<110>, {112}<110>, {335}<110> and {223}<110> is four or less and a pole density of a {332}<113> crystal orientation is 4.8 or less;
• at a depth position that is equivalent to one-eighth of the plate thickness from the surface of the heat-rolled steel plate, a pole density of a {110}<001> crystal orientation is 2.5 or more;
• a number density of fine Ti carbo-nitrides having a particle diameter of 10 nm or less among Ti carbo-nitrides in the heat-rolled steel plate is 1.0×1017 per cm3;
• and
• a bake hardening amount is 15 MPa or more;
• [Ti]−48/14×[N]−48/32×[S]≥0 (1),
• where a content (mass %) of a corresponding element is substituted for each symbol of an element in Formula (1).