grade S690QL for coil steel

Oxygen is a harmful element in grade S690QL steel. With the increase of oxygen content, the strength of grade S690QL steel increased, but the plasticity, especially the toughness, decreased significantly, and the weldability became worse. The presence of oxygen causes hot brittleness of grade S690QL steel.

The alloying principle of low alloy high strength steel plate mainly uses solid volume strengthening, fine grain strengthening and precipitation strengthening produced by alloy elements to improve the strength of low alloy high strength steel plate, grade S690QL. At the same time, the effect of fine grain strengthening on the reduction of ductile brittle transition temperature of low alloy high strength steel platel is used to offset the adverse effect of carbon nitride precipitation strengthening on the rise of ductile brittle transition temperature of steel, so that low alloy high strength steel plate can obtain high strength while maintaining good low temperature performance.

Since 2020, the foreign trade industry has been significantly affected by the epidemic. In the first two months of this year, China's grade S690QL and so on steel exports totaled 7.811 million tons, down 27% year-on-year, the largest decline since March 2018. In terms of steel foreign trade, China is mainly a steel exporting country, with less steel imports.

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