1.What effect does electrogalvanizing have on DC03 and Q235?
Impact on DC03
Advantages: DC03 has a smooth surface (cold rolling process), and the electroplated zinc layer has strong adhesion and good uniformity, and is not prone to leaking or uneven thickness.
A thin zinc layer can meet the needs of moderate corrosion environments (such as indoor equipment and home appliance housings), and the salt spray test can reach 200-500 hours (depending on the zinc layer thickness and passivation process).
Limitations: The zinc layer is thin, and if used outdoors or in a high humidity environment, additional coating (such as spray painting) is required for protection. The risk of hydrogen embrittlement is low (current density is controllable), and it is suitable for stamping parts (such as automotive panels).
Impact on Q235
Advantages: The corrosion resistance can be improved by increasing the zinc layer thickness (such as more than 20μm), which is suitable for light-loaded structural parts (such as furniture hardware).
Limitations: The hot-rolled surface of Q235 is rough, and the zinc layer adhesion may decrease due to residual surface oxide scale during electroplating, and it is easy to peel off or blister.
Thick zinc layer is more expensive, and Q235 has higher strength, which may cause cracks during stamping due to the brittleness of the zinc layer.
2.What effect does hot-dip galvanizing have on DC03 and Q235?
Impact on DC03
Advantages: Thick zinc layer + alloy layer provides long-term corrosion protection (up to 20-50 years in outdoor environment), suitable for high-corrosion scenarios (such as coastal areas).
The cold-rolled surface is clean, the alloy layer is formed evenly during hot-dip plating, and the impact resistance is good (such as automobile chassis parts).
Limitations: The hot-dip plating temperature is high (about 450℃), which may cause slight annealing of the DC03 substrate and a slight decrease in strength (little impact on stamping parts).
The surface is rough (the crystal particles of the pure zinc layer are obvious), and subsequent polishing is required to meet the appearance requirements. Impact on Q235
Advantages: Q235 is a structural steel. The zinc layer thickness can reach more than 100μm after hot-dip plating, and the salt spray test exceeds 1000 hours. It is suitable for outdoor heavy-duty structures such as bridges and towers.
The hot-rolled surface has high roughness, reacts more fully with the zinc liquid, the alloy layer is thick (up to 30μm or more), and the bonding force is extremely strong.
Limitations: High risk of hydrogen embrittlement (substrate carbon content is slightly higher), need to control pickling time and cooling rate after galvanizing. Thick zinc layer leads to rough surface, not suitable for appearance parts.
3.What is the effect of thermal spray galvanizing on DC03 and Q235?
Commonality: The thickness of the zinc layer is controllable, suitable for ultra-thick anti-corrosion needs (such as marine engineering).
The substrate needs to be sandblasted beforehand (DC03 needs additional surface roughening, Q235 hot-rolled surface is easier to handle).
Difference: DC03 needs more stringent sealing treatment after spraying (the surface is smooth and the pores are easy to hide water); Q235 has better adhesion of the sealant due to its rough surface.
Corrosion resistance: After sealing, the two are similar, depending on the thickness of the zinc layer and the sealing quality.
4.What effect does mechanical galvanizing have on DC03 and Q235?
DC03: Suitable for high-strength stamping parts (such as automobile bolts), no risk of hydrogen embrittlement, good uniformity of zinc layer.
Q235: Used for small and medium-sized structural parts (such as standard parts), corrosion resistance is better than electroplating, but lower than hot-dip galvanizing.
Corrosion resistance: Slightly lower than hot-dip galvanizing at the same thickness, salt spray test is about 500-800 hours (depending on post-treatment).
5.What are the core factors affecting corrosion resistance?
Zinc layer thickness: The thicker the thickness, the stronger the corrosion resistance (hot dip galvanizing > thermal spraying > mechanical plating > electrogalvanizing).
Substrate adaptability: DC03 is more suitable for electrogalvanizing and mechanical galvanizing (high surface quality requirements and forming). Q235 is more suitable for hot dip galvanizing and thermal spray galvanizing (high structural strength and thick zinc layer). Post-processing: All processes can further improve corrosion resistance through passivation, sealing and painting (such as hot dip galvanizing + painting can be used in extreme corrosive environments).