Technical Field
[0001] The present invention relates to a plated steel sheet
having excellent corrosion resistance, workability, and
5 surface quality and a method for manufacturing same.
[0002]
Background Art
[0003] A zinc-based plated steel sheet has a sacrificial
10 characteristic in which, when it is exposed to a corrosive
environment, zinc having a lower oxidation-reduction
potential than iron corrodes first to suppress corrosion of
a steel plate. In addition, as zinc in a plating layer is
oxidized, a dense corrosion product is formed on a surface
15 of a steel plate to block the steel plate from an oxidation
atmosphere, thereby improving corrosion resistance of the
steel plate. Due to the advantageous properties as such,
the scope of application of the zinc-based plated steel sheet
has been recently expanded to steel sheets for construction
20 materials, home appliances, and automobiles.
[0004] However, due to an increase in air pollution caused
by industrial advancement, a corrosive environment gradually
deteriorates, and due to strict regulations of resource and
energy conservation, there is a growing need for development
25 of a steel plate having better corrosion resistance than a
Page 3
conventional zinc-based plated steel sheet.
[0005] In order to improve the problem, various studies for
a manufacturing technology of a zinc alloy-based plated steel
sheet, by adding elements such as aluminum (Al) and magnesium
5 (Mg) to a zinc plating bath to improve the corrosion
resistance of a steel plate have been conducted. As a
representative example, there is a Zn-Mg-Al-based zinc alloy
plated steel sheet to which Mg is further added to a Zn-MgAl-based composition system.
10 [0006] Meanwhile, a zinc-based plated steel sheet is
commonly used in a processed state in many cases, and in the
case of a Zn-Mg-Al-based zinc alloy plated steel sheet, a
large amount of an intermetallic compound having a high
hardness is included in the plating layer to deteriorate
15 bending workability, such as causing cracks in the plating
layer at the time of bending processing. Even after being
processed, there is also a problem that zinc in a molten
state during welding by spot welding, or the like, penetrates
along grain boundaries of base iron and causes a so-called
20 liquid metal embrittlement (LME) to cause brittle cracks.
[0007] In addition, although the zinc-based plated steel
sheet after being processed is often provided outside a
product, surface quality is inferior due to surface damage,
and the like, by processing, and thus, it is necessary to
25 improve outer sheet quality.

WE CLAIM:
1. A plated steel sheet, comprising:
a base steel sheet;
a Zn-Mg-Al based steel sheet plating layer provided on
5 at least one surface of the base steel sheet; and
an Fe-Al based inhibition layer provided between the
base steel sheet and the Zn-Mg-Al based plating layer,
wherein the plating layer comprises, by weight:
4% or more of Mg; 2.1 times or more of a Mg content
10 and 14.2% or less of Al; 0.2% or less (including 0%) of Si;
0.1% or less (including 0%) of Sn, with a balance of Zn and
unavoidable impurities.
2. The plated steel sheet of claim 1, wherein, in a
15 cut surface of the steel sheet in a thickness direction,
when an interface line of the base steel sheet is spaced 5
μm apart toward a surface of the plating layer, a length
occupied by an outburst phase intersecting the spaced line
is 10% or less compared to a length of the spaced line.
20
3. The plated steel sheet of claim 2, wherein a Fe
content of the outburst phase is 10 to 45% by weight, and
an alloy phase of the outburst phase contains at least
one of Fe2Al5, FeAl and Fe-Zn compounds, and contains 20% or
25 more of Zn by weight.