含Cr耐腐蚀管线钢的连续冷却转变行为

Continuous cooling transformation behavior for Cr-containing corrosion-resistant pipeline steel

采用Cleeble 1500热模拟试验机测定了含Cr耐腐蚀管线钢的连续冷却转变曲线,并研究了不同冷速下的组织及硬度变化情况。结果表明：只有在0.5℃/s的冷速下,试验钢的组织中才会出现少量的珠光体组织。在1-50℃/s的冷速范围内试验钢的组织均为先共析铁素体＋贝氏体的组织类型,表明在一般的冷却条件下可以获得较相近的组织类型。同时,试验钢CCT曲线上在高温转变和中温转变之间存在较宽的奥氏体亚稳区,有利于得到不同硬度的双相组织构成,确保钢具有相对较高的强度和塑韧性。

CCT curves of Cr-containing corrosion-resistant pipeline steel were determined by using Gleeble 1500 simulator,and the microstructure and hardness of the samples cooled at different cooling rates were tested. The results show that only a small amount of pearlite appears in the tested steel cooled at the cooling rate of 0. 5 ℃/s,and when cooled within the cooling rate range of 1-50 ℃,the microstructure is proeutectoid ferrite ＋ bainite,indicating that such the similar microstructure can be obtained under the conventional cooling condition. A wide metastable zone of austenite forms between the ferrite and the bainite regions in the CCT diagram,which is beneficial to obtain dual-phase microstructures with different hardness,and to ensure the steel to have relative high strength and ductility.