What are the main advantages of S235JR steel pipe?
S235JR steel pipe has excellent forming performance and can be easily subjected to cold processing operations such as bending and stamping. Its welding performance is excellent and can be connected by various conventional welding methods without complicated preheating process. The material cost is relatively low, the market supply is sufficient, the procurement cycle is short, and the cost performance is high. It has good plasticity and toughness, and the impact resistance at room temperature meets most structural requirements. In addition, S235JR steel pipe meets many international standards, which is convenient for export and multinational project application.
What are the limitations of S235JR steel pipe?
The strength is relatively low, and the yield strength is only 235MPa, which is not suitable for high-stress structural parts. In low temperature environment (below -20℃), the toughness decreases significantly, and special attention should be paid to the impact work requirements. The corrosion resistance is general, and surface protection must be performed in humid or corrosive environments. The high temperature performance is poor, and the long-term use temperature should not exceed 300℃. In addition, thick-walled pipes are prone to metallurgical defects such as center segregation, which affects the overall performance.
What are the differences between S235JR steel pipe and S355JR?
In terms of strength, the yield strength of S355JR is about 50% higher, which is more suitable for load-bearing structures. S355JR contains more alloying elements, such as higher manganese content, so the carbon equivalent is also higher, and stricter control is required during welding. In terms of price, S355JR is usually 15-20% more expensive than S235JR, but it can reduce the weight of the structure. In terms of low-temperature toughness, S355JR performs better and is suitable for use in cold areas. In terms of processing performance, S235JR has better cold formability and is more suitable for processing complex shapes.
What problems may occur in the long-term use of S235JR steel pipe?
In a humid environment, unprotected steel pipes are prone to uniform corrosion, resulting in thinning of the wall thickness. Fatigue cracks may occur in stress concentration areas, especially when subjected to cyclic loads. Welded joints are prone to corrosion and special attention needs to be paid to protection. Long-term exposure to industrial atmosphere may cause local corrosion such as pitting on the surface. In addition, in a vibrating environment, the bolted joints may become loose and require regular inspection and maintenance.
How to give full play to the performance advantages of S235JR steel pipes?
Reasonably design the structure to avoid stress concentration and give full play to its plastic deformation capacity. When used in a corrosive environment, appropriate anti-corrosion measures must be selected, such as hot-dip galvanizing or spraying anti-corrosion coatings. Control the processing parameters to avoid excessive cold hardening resulting in a decrease in toughness. Optimize the welding process to reduce welding residual stress and deformation. Perform maintenance inspections regularly to promptly detect and deal with problems such as corrosion and deformation.
