Steel is the main raw material for shipbuilding and marine engineering structure construction, accounting for 20% ~ 30% of the construction cost of hull and marine engineering. The steel A387 Grade 11 Class2 material products involved mainly include steel plates and section steel (marine bulb flat steel, H-beam, angle steel, etc.), casting and forging steel and supporting welding materials, etc. Among them, the amount of steel consumed for hull construction accounts for about 60% of the total ship mass, and sheet metal accounts for about 88%.
In March, the daily output of key iron and steel enterprises decreased on a month on month basis. In terms of enterprise inventory, in late March, the key statistics showed that the A387 Grade 11 Class2 material steel inventory of iron and steel enterprises was 18.067 million tons, a decrease of 3.342 million tons or 15.6% compared with the highest inventory in early March, and an increase of 8.534 million tons or 89.5% compared with the beginning of the year.
The effect of nitrogen on steel performance is similar to that of carbon and phosphorus. With the increase of A387 Grade 11 Class2 material nitrogen content, the strength of steel can be improved, plasticity especially toughness can be significantly reduced, weldability becomes worse, and cold brittleness is intensified. Nitrogen with aluminum, niobium, vanadium and other elements can reduce its adverse effects, improve the performance of A387 Grade 11 Class2 material steel, can be used as an alloying element of low alloy steel.
A few days ago, the relevant person in charge of China National Railway Group Co., Ltd. introduced that since the 18th National Congress of the Communist Party of China, 14 concentrated contiguous poverty-stricken areas, including old and poor, have completed a total of 3.3 trillion yuan in railway infrastructure investment, accounting for 78% of the total railway infrastructure investment; 36,000 kilometers of new lines were put into operation (20,000 kilometers of high-speed rail), accounting for 83% of the new lines put into operation in the country. Up to now, the railway network and 154 trackless stations on the whole road cover about 600 national-level poverty-stricken counties, accounting for 73% of the country's 832 poverty-stricken counties.