Question 1: What are the common connection methods for angle steel during installation? What scenarios are they suitable for?
Answer:
The installation connection methods of angle steel mainly include welding, bolt connection and riveting.
Welding: The angle steel is welded with other components by arc welding or gas welding. It is suitable for permanent structures (such as factory frames). The connection strength is high and the sealing is good, but it is difficult to disassemble and requires fire prevention measures.
Bolt connection: It is fixed with high-strength bolts and nuts. It is suitable for scenes that need frequent disassembly or adjustment (such as temporary brackets and equipment bases). It has high flexibility but needs to be checked regularly for loose bolts.
Riveting: It is mechanically fixed by rivets. It is mostly used in environments with large vibrations (such as bridges and heavy machinery). It has strong vibration resistance but complex process and high cost.
When choosing, it is necessary to consider the purpose of the structure, the type of load and the need for later maintenance. For example, outdoor billboards are usually bolted for replacement, while high-rise steel structures are mainly welded.
Question 2: How to detect whether the quality of angle steel meets the standards? What are the common defects?
Answer:
The quality inspection of angle steel should start from three aspects: size, surface and mechanical properties:
Size inspection: Use calipers and thickness gauges to verify whether the side length, thickness and length meet the tolerance (such as GB/T 706 stipulates that the side width allows a deviation of ±1.5mm).
Surface inspection: Visual inspection or magnetic particle inspection to check for cracks, scars, and rust. Galvanized angle steel needs to test the thickness of the zinc layer (≥40μm is qualified).
Mechanical testing: Tensile strength (such as Q235 requires ≥375MPa) and elongation are determined by tensile tests, and toughness is verified by bending tests.
Common defects include uneven edges and corners caused by uneven rolling, residual oxide scale during hot rolling, and micro cracks at the bends of cold-bent angle steel. The factory needs to conduct batch sampling in combination with national standards and retain the test report.
Question 3: What issues should be paid attention to when using angle steel in extreme climates (such as high cold and high temperature)?
Answer:
Extreme climate has a significant impact on the performance of angle steel, and targeted measures are needed:
High-cold environment (such as -40℃): Low temperature can easily cause brittle fracture of steel, so low-temperature toughness materials (such as Q345D/E) should be selected, and welding should be reduced to avoid embrittlement of the heat-affected zone; impact loads should be avoided during installation, and buffer gaskets should be added at the connection.
High-temperature environment (such as steel mills): Angle steel needs to be made of heat-resistant steel (such as 15CrMo) or coated with high-temperature resistant coating (aluminum-silicon alloy), and a heat dissipation structure should be designed to prevent thermal expansion and deformation.
In addition, areas with large temperature differences need to calculate the amount of thermal expansion and contraction, reserve expansion joints or use sliding supports. For example, the angle steel connection points of desert photovoltaic brackets are often designed as adjustable bolt holes to adapt to the deformation caused by the temperature difference between day and night.
Question 4: How to recycle scrap angle steel? What are the environmentally friendly treatment methods?
Answer:
The recycling of scrap angle steel must follow the "classification-processing-regeneration" process:
Classification and sorting: stack separately according to material (carbon steel, stainless steel) and degree of pollution (whether it contains oil, coating), to avoid mixing and reduce the quality of recycling.
Mechanical processing: cut the angle steel into the required size for smelting through shears and crushers, and separate metal and non-metallic impurities by magnetic separation.
Remelting and regeneration: melt scrap steel in an electric arc furnace, add alloy elements to adjust the composition, and re-roll it into new angle steel, which reduces energy consumption by 60% compared with original steel.
In terms of environmental protection, dust removal equipment is required to reduce smelting smoke, pickling waste liquid needs to be neutralized, and zinc vapor needs to be handled separately when galvanized angle steel is recycled. Some companies directly transform scrap angle steel into small brackets or art components to achieve "upgrading and recycling".
Question 5: What are the innovative applications of angle steel in prefabricated buildings? What is the future development direction?
Answer:
In prefabricated buildings, the application of angle steel presents three major innovative directions:
Modular connection: pre-drilled angle steel is matched with standardized bolt nodes to achieve rapid assembly, such as the frame of a container house can be completed in 1 day.
Composite structure: Angle steel is combined with wood structure and concrete prefabricated panels to form a hybrid load-bearing system, taking into account both strength and lightness (such as loft apartment interlayer bracket).
Intelligent design: optimize the arrangement of angle steel through BIM technology, reduce material waste, and embed sensors to monitor the health of the structure.
In the future, it will develop towards "green intelligence": use recycled steel angle steel to reduce carbon footprint; combine 3D printing technology to customize special-shaped angle steel; develop self-healing coating to extend life. For example, a prefabricated project in Singapore uses AI algorithms to optimize the use of angle steel, saving 15% of costs and shortening construction period.
