Chemical composition and technological process of S355J0W weathering steel

Chemical composition and technological process Weathering steel S355J0W implements the European standard EN10025-5, and considers the mechanical properties and low temperature impact properties of the steel strip, and has made strict internal control regulations on the chemical composition of the steel strip.
Production process: electric furnace → LF+VD refining → rectangular billet continuous casting machine → billet heating furnace → descaling → rough rolling → finishing rolling → cooling → coiling → inspection and storage. S355J0W Weathering Steel Process Control 3.2.1 Smelting Process 1) Converter smelting. The sulfur content of molten iron is less than 0.015%, the content of species is less than 0.008%, and the proportion of molten iron is about 60%. The scrap steel is made of high-quality internally adjusted scrap steel.

During the smelting process of S355J0W weathering steel, foamed slag is made, the fluidity of slag is controlled, and the basicity of slag is controlled to 2.8~3.2. Uniform decarburization to reduce chlorine absorption. Ferro-niobium, silicon-manganese, medium-manganese, alloying, and aluminum-manganese-ferroalloy are used for deoxidation. 10~20 kg of deoxidizer can be appropriately added to the slag furnace times in the converter.

Adding order: see the steel flow, add part of Al-Mn ferromanganese first for deoxidation, then add medium manganese and silicon-manganese in turn, add the remaining Al-Mn ferromanganese during the alloying process, and add all the alloys before slag blocking. LF refined. Refining can supplement the aluminum line according to the entry conditions, use calcium carbide and silicon carbide to make slag, keep the yellow-white slag or white slag for more than 10 minutes, and perform calcium treatment at the end point, and the soft blowing time is more than 10 minutes.

S355J0W weathering steel VD degassed. Vacuum time > 18 min, vacuum degree < 67 Pa and hold time > 12 min. After the hole is broken, if the acid-soluble aluminum content is greater than 0.015%, in principle, the aluminum wire will not be supplemented, and the S355J0W weathering steel will be covered with a covering agent in time.