What is the role of LR grade D seafaring ship steel in the industry

Steel pipe refers to the steel with openings at both ends and hollow section, and its length is larger than that of surrounding steel. According to the processing technology, it can be divided into seamless steel pipe and welded steel pipe, LR grade D seafaring ship steel. The production methods mainly include hot rolling, cold rolling, extrusion, cold drawing, forging, welding, etc. The size range of steel pipe is very wide, from capillary with small diameter to large diameter pipe with several meters. Steel pipe can be used for pipeline, thermal equipment, mechanical industry, petroleum geological exploration, container, chemical industry and special purpose.

The steel such as LR grade D seafaring ship steel delivered in the hot-rolled state has a certain degree of corrosion resistance due to the high temperature, so it can be stored in the open air. However, this layer of oxide scale also makes the hot-rolled steel surface rough and the size fluctuates greatly. Therefore, the steel with smooth surface, accurate size and good mechanical properties is required to be produced by using hot-rolled semi-finished products or finished products as raw materials and then cold rolling.

In 2019, the output of pig iron in the world was 1.265 billion tons, with China accounting for 64%; the overseas output accounted for 36% (460 million tons), ranking 86.982 million tons of EU 28 countries, 74.907 million tons of Japan, 74.099 million tons of India, 73.264 million tons of CIS, and LR grade D seafaring ship steel 47.521 million tons of South Korea.

A131 EH36 steel is high strength marine grade hull structural steel. Its yield strength is no less than 355Mpa, tensile strength is 490-620 Mpa, and elongation is 19% min. LR grade D seafaring ship steel, EH36 steel strength is close to S355 steel. However, EH36 steel is shipbuilding steel, while S355 steel is carbon structural steel, and can not be certified by classification society. That is to say, S355 steel is not allowed to be used for ship building when there is certificate requirement. A131 EH36 steel is widely used to build ships working in low temperature water.