Generally, spring steel can be produced by electric furnace, open hearth furnace or oxygen converter; high quality spring steel with good quality or special performance can be refined by electroslag furnace or vacuum furnace. In the spring steel, the main content of carbon, manganese, silicon and other major elements is narrow, and the chemical composition must be strictly controlled during smelting. When the silicon content is high, defects such as bubbles are easily formed, and white spots are easily generated when the steel ingot is cooled after the forging. Therefore, the raw materials used for smelting must be dried to remove gases and inclusions as much as possible, and to avoid overheating of molten steel.
Spring steel must pay special attention to decarburization and surface quality during rolling. When the steel surface is severely decarburized, the fatigue limit of the steel is significantly reduced. For high silicon spring steels such as 70Si3MnA, care should be taken to avoid graphitization. Therefore, the temperature of the stop rolling should not be too low (≥850 °C) during hot working to avoid excessive residence time in the temperature range (650-800 °C) where graphitization is easy to form.
After the spring is made, the shot peening can produce residual compressive stress on the surface of the spring to offset some of the working stress on the surface layer and suppress the formation of cracks in the surface layer, which can significantly increase the fatigue limit of the spring.
PP ( Uniaxial geogrids ) : Ultimate Tensile Strength 30kN/m to 300kN/m, PP geogrids (Uniaxial ) range : Flexurally stiff biaxial monolithic and integrally formed Geogrid constructed of PP- Polypropylene or HDPE – polyethylene by a unique punching and drawing process .
1. It reinforce old asphalt concrete road surface and asphalt layer, and prevents damage ;
2. It is used for rebuilding cement concrete road surface into composite road surface and restraining reflection caused by block contraction .
3. It is used in road expansion and improvment project and crack caused by old and new combination position and uneven sedimentation ;
4. It is used in soft soil base reinforcement treatment , is favorable for soft soil water separation and concretion,restrains sedimentation effectivly,distributes stress uniformly and improve overall strength of road base;
5. It is sued for preventing contraction crack caused by new road semi-rigid base layer,and reinforces and prevents road surface crack caused by foundation crack reflection.
Extruded Pp Uniaxial Geogrid, PP Uniaxial Geogrid, Ux Geogrid Used For Road Construction
Feicheng Lianyi Engineering Plastics Co., Ltd , http://www.lianyigeosynthetics.com