Renting Steel Formwork Rental Station: How to Determine the Material and Density of Steel Formwork?

1、 Material identification method
Chemical composition analysis
Use a spectrometer to detect the content of carbon (C), manganese (Mn), silicon (Si) and other elements:
Q235 steel has a carbon content of 0.14-0.22%, Q345 steel has a carbon content of ≤ 0.20%, and manganese content is 1.00-1.60%
Stainless steel (such as 304) needs to be tested for chromium (Cr ≥ 18%) and nickel (Ni ≥ 8%) content
Laboratory commonly used electron probe X-ray microscopy analysis with an accuracy of 0.01%
Physical performance testing
Hardness test: Q235 hardness HRC ≤ 22, Q345 can reach HRC40-55 after heat treatment, stainless steel 304 hardness HRC ≤ 30
Impact test: Q345E needs to pass a -40 ℃ low-temperature impact test to determine material toughness based on fracture morphology
Appearance discrimination method
Q235 has a red oxide layer after natural cooling, while Q345 has a black surface after rapid cooling process
Poor quality steel often has folding cracks or rough surface defects, and poor material uniformity
Label verification
The factory label of regular steel formwork shall indicate the standard number and yield strength value of GB/T 700 (Q235) or GB/T 1591 (Q345)
2、 Density determination method
||Method Type | Operation Points | Applicable Scenarios|
|-|-|-|
|Measurement method | Mass/volume method | ① Accurate weighing (error ≤ 0.1kg)
② Measuring the volume of irregular parts using the water level method | Irregular templates or special alloy steel|
|Table lookup method | Material matching | Q235 density 7.85g/cm ³, Q345 density 7.87-7.91g/cm ³, stainless steel 304 density 7.93g/cm ³ | Standard specification template|
Example calculation:
A Q235 steel formwork is 2m long, 1m wide, and 8mm thick, with a weight of 2 × 1 × 0.008 × 7850=125.6kg. When the measured weight is 128kg, the error is 1.9%. It is necessary to check whether the material is doped
3、 Application scenario adaptation
Bridge engineering: Q345 (density 7.91g/cm ³) is preferred, with a yield strength of 345MPa, which is 47% higher than Q235
Civil building: Q235 (density 7.85g/cm ³) meets conventional loads and has a cost reduction of 15-20%
Food equipment: Stainless steel 304 must comply with GB 4806.9 migration test standard, with a density corrected to 7.93g/cm ³
Attention:
Material determination requires a combination of chemical, physical, and visual methods, with a single detection error of up to 30%
The density calculation should be combined with the national standard thickness tolerance (± 0.25mm), and the weight error should be controlled within ± 2%
Important projects require a third-party testing agency to issue a CMA certification report