Fe-based electroplated steel sheet, electrodeposition-coated steel sheet, automotive part, method of producing electrodeposition-coated steel sheet, and method of producing Fe-based electroplated steel sheet

An Fe-based electroplated steel sheet comprising:

• a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less;
• and
• an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of 25.0 g/m2 or more, wherein
• a ratio of a ratio of crystal grains in the Fe-based electroplating layer whose orientation is the same as that of crystal grains in the Si-containing cold-rolled steel sheet is more than 50% at an interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet, the ratio being measured by
• taking a sample of 10 mm×10 mm in size from the Fe-based electroplated steel sheet,
• processing any part of the sample with a focused ion beam (FIB) device to form, at the processes part, a 45° cross section at an angle of 45° relative to the direction of a T-section, which is a cross section parallel to a direction orthogonal to the rolling direction of the steel sheet and perpendicular to the steel sheet surface, with a width of 30 μm in a direction orthogonal to the rolling direction and a length of 50 μm in a direction 45° relative to the T-section direction as a sample for observation,
• observing the center of the 45° cross section of the sample for observation at a magnification of 5000× using a scanning ion microscope (SIM) to capture an 8-bit SIM image with a width of 1024 pixels and a height of 943 pixels, and
• determining the ratio based on the following equation:
• (Ratio of crystal grains in the Fe-based electroplating layer whose orientation is the same as that of crystal grains in the Si-containing cold-rolled steel sheet at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet)=((Length of the area where the crystal grains in the Fe-based electroplating layer whose orientation is the same as that of crystal grains in the Si-containing cold-rolled steel sheet at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet)/(Length of the interface in the observation field of view))×100.