20 # material is a high-quality low-carbon carbon steel, cold-extruded, carburized and hardened steel. A709 Gr 50 bridge steel plate, 20 # material has low strength, good toughness, plasticity and good weldability. Chemical composition of 20 # round steel bar: C: 0.17 ~ 0.23, Si: 0.17 ~ 0.37, Mn: 0.35 ~ 0.65, S: ≤0.035, P: ≤0.035, Cr: ≤0.25, Ni: ≤0.30, Cu: ≤0.25. 20# carbon steel mechanical properties: Shear strength 275 ~ 392MPa, Tensile strength is 253 ~ 500MPa, elongation min. 25%.
The cold working performance of A709 Gr 50 bridge steel plate and so on steel structure engineering steel is good, which can ensure that the steel will not crack or brittle fracture during high-temperature processing, and will not have a great impact on strength, plasticity and toughness due to processing. The durability of A709 Gr 50 bridge steel plate and so on steel structure engineering steel is good. Durability refers to the service life of steel structure. The main factor affecting the service life of steel is the poor corrosion resistance of steel, followed by the deterioration of mechanical properties of steel under long-term load, repeated load and dynamic load.
South Korean A709 Gr 50 bridge steel plate steel industry said that the slowdown in economic growth superimposed on the impact of the epidemic, steel demand weakened, exports were sluggish, enterprises are facing huge operating pressure. Due to the delay in the resumption of work of Chinese A709 Gr 50 bridge steel plate steel enterprises, the steel inventory is growing rapidly. According to statistics, China's steel circulation inventory reached 23.75 million tons in February, the highest since 2006, with an estimated total inventory of 33.45 million tons.
Affected by the increase in coal trucks, the increase in sales, and the superimposed impact of accidents, sentiment has improved, and coal prices in Shanxi, Shaanxi, and Mongolia have seen an overall rise. In terms of ports in the Bohai Sea Rim, the Daqin line is connected to the eight ports, and the number of superimposed ports is not low, which promotes the general storage effect and the market is seriously out of stock of high-calorie and low-sulfur coal. In addition, due to the impact of rising futures and mining disasters, the market's bullish sentiment has increased, and the quotations of shipping companies generally rise.
