Effect Of Thermomechanical Treatment On Microstructure And Properties Of The Compact Strip Production As Contained C-Mn Steel Microalloyed By Nb, Ti And Cr

As always goes along with Thin Slab Casting and Rolling process as a harmful element. This article introduces the effect on microstructure , properties and the change of As microdistribution undergo different heat treatment and hot rolling process.From the study of trace-As steel using TEM and AES, it is found out: As segregates to the grain boundaries gradually after different heat treatment; When the heat preservation time is short, there is no diffusion to the outward; after a long time, As diffuses to the outside from the grain boundary along with dissloving into the grain until the content of As reaches a balance. Hot rolling process makes the microdistribution of As be more uniform. It is also found that the structure changes to martensite after reactions at 950℃and 1100℃for 0.5hrs cooling with water; when the time extending to 2hrs, it changes to ferrite, which grows up obviously at 1100℃; the content of carbides decreases along with the increase of holding temperature and time, which start from the carbides of Cr and Nb; the carbides of Ti are stable. After the heat treatment, dislocation density decreases gradually. It almost disappears after a further reaction at 1100℃; at the same time the recrystallization has finished. Hot rolling process makes a lot of Ti and Nb precipitate; and a lot of small carbides arise at the dislocation.After the study of high-As steel using SEM, we can find that As segregates to the grain boundary during the process of making high-As steel. After the heat treatment, As always moves to the oxide film besides congregating in the grain boundary. The content of As is the highest in the grain boundary nearby the oxide film.