正火温度轧制和正火处理的S355NL钢板的力学性能和显微组织

Mechanical Properties and Microstructure of S355NL Steel Plate Rolled at Normalized Temperature and Normalized

分别采用正火温度轧制和正火处理工艺试制了根据欧洲标准EN10025-3细晶粒钢设计、含0.12%~0.16%(质量分数)C和Nb、V、Ti等微合金元素的40和60 mm厚S355NL钢板,检测了钢板的力学性能和显微组织。结果表明:在正火温度轧制的60 mm及以下厚度的S355NL钢板,其-40℃冲击吸收能量不低于150 J,-50℃冲击吸收能量不低于27 J,-60℃冲击吸收能量小于27 J,而正火处理的钢板其-40℃冲击吸收能量不低于200 J,-50℃冲击吸收能量不低于150 J,-60℃冲击吸收能量不低于100 J;正火温度轧制和正火处理的钢板显微组织均为铁素体和少量珠光体,前者晶粒度为8.0~10.0级,后者晶粒度为9.5~11.0级,因此具有更好的低温韧性。

40-mm-and 60-mm-thick S355 NL steel plates, which was designed on the basis of European standard EN10025-3 fine-grained steel and contained 0.12% to 0.16% C by mass and micro-alloying elements such as Nb, V and Ti were trial-produced by rolling at normalizing temperature and by normalizing, respectively. The steel plates were tested for mechanical properties and microstructure. The results showed that(a) the 60-mm or less thick S355 NL steel plate rolled at normalized temperature exhibited impact absorbed energy of 150 J or higher at-40 ℃, 27 J or higher at-50 ℃ and lower than 27 J at-60 ℃;(b) the steel plate normalized exhibited impact absorbed energy of 200 J or more at-40 ℃, 150 J or more at-50 ℃, and 100 J or more at-60 ℃;and(c) the steel plate rolled at normalized temperature and the steel plate normalized all manifested microstructure consisting of ferrite and a small amount of pearlite, the former exhibited 8.0 to 10.0 grades of grain size, whereas the latter exhibited 9.5 to 11.0 grades of grain size, and therefore better low-temperature toughness.