A base steel sheet is disclosed having a specified chemical composition and a steel microstructure at a quarter thickness position containing specified ranges of ferrite, fresh martensite, retained austenite, bainite, tempered bainite, and tempered martensite, the value obtained by dividing the total area fraction of isolated island-like fresh martensite and isolated island-like retained austenite by the sum of the area fraction of fresh martensite and the volume fraction of retained austenite in a ferrite grain is 0.65 or more, the isolated island-like fresh martensite and the isolated island-like retained austenite in the ferrite grain has an average grain size of 2.0 m or less, and the amount of diffusible hydrogen in the base steel sheet is 0.50 ppm by mass or less.

A steel welded member comprising a plurality of Zn-based plated steel materials, each having a Zn-based plating layer on a surface of a steel material, joined together through at least one spot weld, wherein the steel material contains, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, the steel welded member includes, by area ratio, 20 to 80% of a phase (Fe.sub.3 Zn.sub.10) and at least one oxide with a long axis of 0.5 m or more in a region up to 0.5 mm from an end part of a pressure weld of the spot weld.

A steel part includes a steel sheet substrate and a coating on at least one surface of the steel sheet substrate. The coating includes between 0.2 and 0.7% by weight of Al, with a remainder of the metal coating being Zn and inevitable impurities. The steel sheet substrate and the coating have at least one deformation. An outer surface of the coating has a waviness Wa.sub.0.8 of less than or equal to 0.43 m.

A coated metal sheet includes a steel substrate and a coating on at least one surface of the steel substrate. The coating includes between 0.2 and 0.7% by weight of Al, with a remainder of the metal coating being Zn and inevitable impurities. The coated metal sheet was subjected to a skin pass operation after coating. An outer surface of the metal coating has a waviness Wa.sub.0.8 of less than or equal to 0.55 m.