Pressler coating technology
Pressler independent research and owns the proprietary intellectual property rights:CN109821951A, CN109136907A, CN109021630A
Pressler coating technology is based on the Pressler vacuum hot-press molding line. The non-surface-treated hot-pressed products produced by the vacuum hot-press molding line match the Pressler coating technology, such as galvanizing Treatment can greatly improve the anticorrosive performance of parts, and has great application value for wet areas such as the chassis of the automotive industry.
Coatings that can be used in thermoformed products are classified as follows:
According to coating alloy material: there are aluminum-based coating, zinc-based coating, nickel-based coating, chromium-based coating, manganese-based coating
According to the plating method: hot plating, water plating, spraying
According to the plating schedule: there are first plating and then hot forming, there are first thermoforming and then plating
According to the melting temperature of the coating alloy: there are low-melting alloy coatings such as aluminum-based, zinc-based; there are high-melting alloy coatings, such as nickel-based, chromium-based, manganese-based
According to the high temperature oxidation resistance of the coating alloy: there are high temperature oxidation resistant alloy coatings such as aluminum, nickel and chromium based; there are non high temperature oxidation resistant alloy coatings such as zinc and manganese based.
Coating technologies commonly used in the thermoforming industry:
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Aluminum silicon coating |
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Zinc-based coating |
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Uncoated plate |
Aluminum silicon coating features
• Hot-dip / spray, usually applied in steel mills.
• Plating before hot forming. The coating undergoes austenitizing temperatures above 860 ° C during hot pressing.
• Low melting point, its melting temperature is around 680 ° C.
• High temperature oxidation resistance, the surface oxide film prevents the inner layer from further oxidation.
• Brittle intermetallic compounds are formed between the coating and the substrate during hot plating.
• The coating is mainly composed of intermetallic compounds after hot pressing. Its electrode potential is close to that of the base iron. It does not have sacrificial anode protection under the corrosive electrolyte environment.
• The melting point (1100 ° C) of the intermetallic compound is higher than the forming temperature during hot pressing.
• The aluminum coating needs to be removed during patch welding before hot pressing. Aluminum-iron welding will produce brittle intermetallic compound inclusions in the weld.
• Not suitable for cold forming before hot pressing, due to brittle intermetallic compounds in the hot-dip coating.
• Rapid cooling during hot pressing causes a large number of cracks in the coating, and corrosive electrolytes can easily reach the substrate through the cracks.
• The melting point of the coating is lower than the austenitizing temperature. When the coating is melted, it will stick to the furnace roll and form nodules on the surface of the furnace roll.
• The austenitizing heating of the coated steel plate requires additional alloying time, which is longer than the bare plate.
• The aluminum in the coating reacts with water vapor in the furnace to generate hydrogen that penetrates into the substrate and causes hydrogen embrittlement. The furnace atmosphere needs to be dry and low dew point control is required.
• Aluminum-silicon coated hot-pressed products have lower welding performance than bare boards, require larger welding currents, and have lower electrode life.
• The iron-aluminum intermetallic compound in the coating is relatively brittle, and the cold bending performance of hot-pressed products is lower than that of bare boards.
• The coating has low corrosion resistance after hot pressing, only physical covering. The anti-corrosion protection ability for cuts and tailor welds is zero.
Zinc-based coating features
• Hot-dip / spray, usually applied in steel mills.
• Plating before hot forming. The coating undergoes austenitizing temperatures above 860 ° C during hot pressing.
• Low melting point, its melting temperature is around 420 ° C.
• Not resistant to high temperature oxidation, fluffy oxide scale will be produced on the surface when heated at high temperature, and the oxide scale needs to be removed after hot pressing.
• The intermetallic compounds generated by the coating and the substrate are less brittle during hot plating and can be cold formed.
• If the alloy is heated for a long time during hot pressing, the coating is mainly α-phase iron-zinc solid solution, and the welding performance is good.
• The potential of the iron-zinc solid solution electrode is close to that of the base iron, and it does not have the sacrificial anode protection function in a corrosive electrolyte environment.
• If the alloy is heated for a short time during hot pressing, the coating contains a large amount of Γ-phase brittle zinc-iron intermetallic compounds, the electrode potential of which is lower than that of the matrix iron, and it has a sacrificial anode protection function, but the coating is very brittle.
• If the alloy is heated for a shorter time during hot pressing, the melting point of the δ phase (419 ° -650 ° C) of the intermetallic compound in the coating is lower than the forming temperature, and the liquid substance of the coating penetrates into the large strain area of the substrate during forming. The substrate cracks during cooling after the hot pressing is finished, which is caused by the difference in the expansion coefficient of the coating material and the substrate that penetrated between the grains of the substrate.
• Rapid cooling during hot pressing causes a large number of cracks in the coating, and corrosive electrolytes can easily reach the substrate through the cracks.
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Disadvantages of hot-dip low-melting alloy coatings: |
Coating Technology from Pressler：
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Pressler zinc-based coating |
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Pressler uncoated plate |
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Features of Pressler coatings: |
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Uncoated bare board products • Vacuum heating • No scale • No shot blasting required • No deformation • Lowest cost |
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Zinc coated products • Electroplating process after hot forming • Dense and complete coating • With sacrificial anode protection • Best corrosion resistance |
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Pressler coating application
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 Electro-galvanized tailor-welded door rings |
Electro-galvanized tailor-welded door rings
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 Bare board patch coating |
Comparison of Pressler coating and hot-dip AI-Si / Zn coating gold
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原材 30um
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原材 9um
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热压后 40um
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热压后 18um
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Hot aluminized silicon coating
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Hot-dip galvanized coating
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Pressler galvanized coating case
Electro-galvanized body |
Galvanized layer 5um |
Comparison of Anti-Corrosion of Pressler Coating and AI-Si Coating
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Hot-dip aluminized silicon coated B-pillar 24H neutralsalt spray |
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Electro-galvanized B pillar 72H neutral salt spray after hot pressing |
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Corrosion resistance comparison between Pressler
manganese coating and AI-Si coating
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Hot-dip aluminized silicon coated flat plate hot-pressed 48H neutral salt spray |
Comparison of corrosion resistance of thermoformed products
(720H neutral salt spray)
Bare board thermoforming (720h salt spray) |
AlSi sheet thermoforming (720h salt spray) |
GA sheet thermoforming (720h salt spray) |
Galvanizing after bare forming (720h salt spray) |
Bare
plate
Original weight
(g)
Weight after 720H
Corrision
(g)
Weight loss
(g)
Percentage
for loss
Square
(mm²)
Loss for square
(g/mm²)
Bare
plate
185.26
147.15
36.48
19.69%
19006
1.9E-3
Al-Si
Plate
149.69
148.78
2.54
1.69%
18400
1.38E-4
GA Plate
241.73
237.57
4.16
1.72%
10504
3.96E-4
GAlvanized
Plate
235.85
235.74
0.11
0.4%
19173
5.74E-6
Coatings of Thermoformed Products (720h Salt Fog)
 Bare plate |
Al-Si plate |
 GA plate |
 Bare plate after galvanized |
 Bare plate base material |
 Al-Si plate base material |
 GA plate base material |
 Galvanized basematerial |
Original
material
Scratch
width after thermoforming electrophoresis (mm)
Corrosion
width of coating after 720h salt spray (mm)
720h
salt spray scratch corrosion width (mm)
720h
salt spray substrate corrosion width (mm)
Bare
plate
1.20
8.51
1.54
1.54
Al-Si
1.479
9.42
3.22
3.22
GA
0.938
6.67
9.45
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Galvanized
0.957
6.08
7.38
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Performance comparison of several thermoformed coating products
Coating
Tensile
Yield
Stretch rate
Hydrogen content (ppm)
Corrision Velocity
Standard for hot forming
1300-1650
950-1250
≥5.0
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Bare plate
1472.00
1010.32
6.9
2.01
1.9E-3
Al-Si plate
1522.81
1144.49
6.58
3.32
1.38E-4
GA plate
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3.96E-4
Pressler Galvanized
1462.18
1147.76
6.20
3.51
5.74E-6
(Mpa)
(Mpa)
(%)
(g/mm²)
Pressler thermoforming process route (uncoated products)
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Blanking |
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Trailor welding |
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Hot forming |
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Cutting edges & holes |
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Applying oil |
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Laser blanking line |
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Laser trailor welding line |
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Non-oxygen heating forming line |
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3D laser cutting machine |
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Applying oil line |
Pressler thermoforming process route (hot-dip galvanized products)
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Blanking |
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Trailor welding |
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Hot forming |
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Cutting edges & holes |
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Galvanized
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| Laser blanking line |
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Laser trailor welding line |
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Non-oxygen heating forming line |
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3D laser cutting machine |
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Galvanized |
