A588 Weathering Steel Plate Rolling Process

Since A588 weathering steel is a copper-containing steel, the melting point of Cu is relatively low, so the entire rolling process is a key link in the production of weathering steel.

Copper-containing steel is prone to cracks caused by copper brittleness during heating and rolling. The main reason for copper brittleness is that when the steel is heated at high temperature, selective oxidation occurs on the surface of the steel, and copper elements will gradually be enriched in the metal matrix and the oxide layer. interface, the longer the heating time of the steel, the thicker the oxide skin layer, and the correspondingly more residual copper elements will be enriched on the surface. If the hot working temperature of the steel is above the melting point of copper (1083°C), the liquid film-like copper enriched on the surface will wet the surface of the steel and infiltrate into the matrix along the grain boundary.

At the same time, the copper-rich austenite grain boundary oxidation also becomes quite serious, and the amount of oxygen entering the matrix along the grain boundary increases, which not only diffuses along the grain boundary to form an oxide layer, but also diffuses inward from the oxide layer along the entire matrix to form several Dispersed fine particles of iron-manganese-silicate, which makes the grain boundary strength of the enriched layer even lower, resulting in a more brittle bond between the substrate and the surface, and finally leads to severe copper cracking.

The C content and alloy content of A588 weathering steel are generally low, so it can be processed by referring to the processing specifications of ordinary low alloy steel. Processing is mainly considered the influence of Cu. If the Cu content is too high and the heating time is too long, Cu with a low melting point will be enriched during processing and erode the grain boundaries, resulting in cracking. In order to prevent thermal cracking of the copper billet, it is advisable to use a reducing gas during heating, and at the same time, pay attention to a reasonable heating temperature and heating time, and roll it in time to avoid waiting for rolling.

After heating, the temperature difference of the steel plate cannot be higher than 50°C. The final rolling temperature difference should be less than 30°C. At the same time, it is necessary to control and display various rolling process parameters before and after rolling in the rolling mill, and pay attention to maintaining the correct final rolling temperature and post-rolling cooling method. When each Cu-containing steel is rolled, it should be stacked and managed according to the local resource conditions, so as to prevent Cu pollution caused by the returned scrap steel used in smelting other steel types.