Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (9): 18-23.DOI: 10.13251/j.issn.0254-6051.2024.09.003

• MICROSTRUCTURE AND PROPERTIES • Previous Articles     Next Articles

Effect of continuous annealing on microstructure and properties of 350 MPa cold-rolled high corrosion resistant weathering steel

Wang Nai, Ma Degang, Li Jianying, Ma Guangzong, Sun Lu, Sun Hongliang, Ji Minglong   

  1. Gaoqiang Automobile Plate Co., Ltd., Tangshan Iron and Steel Group Co., Ltd., Tangshan Hebei 063000, China
  • Received:2024-03-16 Revised:2024-07-14 Online:2024-09-25 Published:2024-10-29

Abstract: Effect of continuous annealing process on microstructure and properties of 350 MPa cold-rolled high corrosion resistant weathering steel was studied by simulating continuous annealing process with Gleeble-3500 annealing machine. The results show that with the increase of annealing temperature, the strength of the tested steel decreases first and then increases, the annealing temperature is the key factor affecting the microstructure and properties of the tested steel, whereas, the effect of strip speed, slow cooling temperature and rapid cooling temperature on properties of the tested steel is limited. When the annealing temperature is lower than 800 ℃, only recovery and recrystallization in the tested steel occur, and the microstructure is composed of ferrite and carbide, the strength of the tested steel decreases with the increase of annealing temperature. When the annealing temperature is 800 ℃, the yield ratio reaches a minimum value of 0.53, exhibiting the characteristics of duplex steel, and is annealed at the critical austenitizing temperature Ac1. When the annealing temperature is higher than 800 ℃, the tested steel occurs recovery, recrystallization and austenitization transformation, and the microstructure is composed of ferrite, bainite and carbide after cooling, and the strength of the tested steel increases with the increase of annealing temperature. Based on the comprehensive analysis, two process routes, low-temperature annealing and high-temperature annealing, can be used in industrial production to obtain the tested steel that meet the standard requirements.

Key words: high corrosion resistance weathering steel, continuous annealing, strength, microstructure

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