Rental of construction steel formwork: How to choose suitable steel formwork materials?

1、 Comparison of Material Classification and Technical Indicators
Material type, yield strength, corrosion threshold (Cl ⁻), applicable scenarios
Q235 carbon steel ≥ 235MPa ≤ 50ppm short-term dry environment (≤ 3 years)
Q345 low-alloy steel ≥ 345MPa ≤ 80ppm heavy-duty bridge/high-rise building
304 stainless steel ≥ 205MPa 200ppm conventional humid environment
316L stainless steel ≥ 170MPa 500ppm marine/chemical corrosive environment
2、 Selection of core parameter control
Thickness tolerance
Adopting N-class deviation standard (± 0.3mm/10mm thickness)
The thickness of key load-bearing areas is ≥ 6mm, and non load bearing areas are ≥ 3mm
Load matching
Conventional building formwork: bearing capacity ≥ 15kN/m ²
Bridge large-span formwork: bearing capacity ≥ 25kN/m ² (requires Q345 material)
Welding process
Carbon steel welding current: 110-150A for plate thickness ≤ 8mm, 150-220A for plate thickness ＞ 8mm
Stainless steel welding adopts argon arc welding, with inert gas purity ≥ 99.99%
3、 Environmental adaptation plan
Corrosive environment
Coastal areas: 316L stainless steel composite template (stainless steel panel+Q235 skeleton)
Industrial zone: hot-dip galvanizing treatment (zinc layer ≥ 80 μ m)
Extreme temperature
-Environment below 20 ℃: Q345D/E grade low-temperature steel is selected
High temperature workshop (>150 ℃): select refractory steel (strength retention rate ≥ 70% at 600 ℃)
4、 Economic Comparative Analysis
Comparison item: Carbon steel template, stainless steel composite template
Initial cost (yuan/square meter) 320-400 850-1200
Maintenance cycle: 6 months/time, 24 months/time
High lifecycle cost (5 years+45%) and low (5 years+18%)
Conclusion: For projects with a project cycle of more than 3 years or corrosive environment engineering, the comprehensive cost of stainless steel composite templates can be reduced by 27% -35%
5、 Key points of process control
Surface treatment
Sandblasting treatment with Sa2.5 grade (roughness Ra12.5-25 μ m) enhances concrete adhesion
Dry film thickness of anti rust coating ≥ 120 μ m
Molding accuracy
Laser cutting tolerance ± 0.5mm/10m
Bending angle compensation: Carbon steel 1-2 °, stainless steel 3-5 °
Through the above system selection, the service life of steel formwork can be increased by 50% -200%, and the qualified rate of concrete forming can be stabilized at over 98%