Steel sheet plated with zinc-aluminum-magnesium-calcium alloy by means of hot dipping and manufacturing method therefor

A steel sheet hot-dipped with a zinc-aluminum-magnesium-calcium alloy coating, comprising a steel substrate and an alloy coating on a surface of the steel substrate, wherein the alloy coating comprises the following chemical elements in mass percentages:

• Al:
• 12-27%, Mg:
• 2-8%, Ca:
• 0.02-5%, Si:
• 0.15-1.0%, optionally one or both of Ti:
• 0.01-0.1% and B:
• 0-0.05%, and a balance of Zn and unavoidable impurities;
• wherein the mass percentages of Al, Mg and Ca in the alloy coating further satisfy the following relationships:
• 4%≤(Mg+Ca)≤10%, Al/(Mg+Ca)≥2.5;
• wherein the alloy coating has a microstructure comprising:
• an Al-rich phase, a MoZn2 phase, a Zn-rich phase and a Mg2Si phase, and a granular intermetallic compound enriched with elements Mg and Ca;
• wherein the granular intermetallic compound includes at least one of the following:
• MoZn2, Mg2Si, Al2Ca, Al4Ca, Al2CaSi2, and Ca3Zn;
• wherein the alloy coating has a hardness of 140-240 Hv;
• and
• wherein there is no obvious defects on the surface of the alloy coating, or the number of defects is ≤4/100 m on the surface of the alloy coating when rated by observing with naked eyes, and there is no peeling from the alloy coating or there are 1-2 peeling points on the tape visible to naked eyes when tested according to a T-bend adhesion evaluation.