Q345E steel production process and rolling process

Low alloy structure and high strength steel Q345E steel can be used in the part of railway vehicle and meet the requirements of speed increase of railway vehicle in our country. The customer orders to our company according to GB/T1591-2008 standard, and put forward in the contract the yield strength and tensile strength of Q345E steel are 40 N/mm2 and 80 N/mm2 higher than GB/T1591-2008 special requirements.

Normally, Q345E steel final rolling temperature is 1000 ℃, the rolled steel yield strength, tensile strength can meet the requirements of GB/T1591-2008 standard, but can not meet the user put forward higher than GB/T1591-2008 yield strength, tensile strength requirements. To achieve the desired value, the rolling process must be improved to improve the strength of Q345E steel.

The production process line of Q345E steel is: steelmaking -LF-VD- rectangular continuous casting billet - heat feed/slow cooling- heating - rolling - cooling - finishing - inspection, inspection- submission. The key control link is electric furnace/converter smelting and continuous casting mill rolling, but the main test is still carried out in rolling process.

Different heating temperature, final rolling temperature and cooling mode are adopted in continuous casting billet rolling. The original process is: heating temperature 1260℃~1280℃, opening temperature 1180℃~1200℃, final rolling temperature 1000℃, Q345E steel pile cold. The new process is the final rolling temperature of 900℃~950℃ and 850℃ control, and control below 900℃ total deformation of 30%. At the same time in the cold bed with a fan quickly cooled to 500 ℃ below collection, pile cold.