高温热处理对节约型2101双相不锈钢组织性能的影响

Effect of high temperature heat treatment on microstructure and properties of lean duplex stainless steel 2101

对节约型2101双相不锈钢连铸坯试样在1180、1200、1220和1240℃进行高温热处理,通过光学显微镜、扫描电镜、透射电镜和显微硬度计等分析了2101双相不锈钢的显微组织、奥氏体含量及其硬度随加热温度和保温时间的变化规律。结果表明:在相同保温时间下,随着温度升高,2101双相不锈钢中奥氏体含量逐渐降低,晶粒逐渐粗化,奥氏体与铁素体的两相硬度差逐渐减小;在1240℃时,铁素体相的晶界及晶界内有大量的脆性相析出;TEM分析表明,这些析出相为六方结构的Cr_(2)N相;在相同的加热温度下,随着保温时间的延长,奥氏体的含量逐渐增加,奥氏体与铁素体的两相硬度差逐渐增加。

The high-temperature heat treatment at 1180 ℃, 1200 ℃, 1220 ℃ and 1240 ℃ for lean duplex stainless steel 2101(LDX2101) continuous-casting slab was carried out. Microstructure, austenite content and hardness of the duplex stainless steel 2101 heated at different temperatures for different time were analyzed by means of optical microscope, scanning electron microscopy, transmission electron microscopy and microhardness tester. The results show that under the same holding time, with the increase of heat treatment temperature, the austenite content of the duplex stainless steel 2101 decreases, the grain is coarsened, and the hardness difference between austenite and ferrite decreases. When the heat treatment temperature is 1240 ℃, a large number of brittle phases precipitate at and within grain boundary of ferrite phase. TEM analysis shows that these precipitates are Cr_(2)N phases with hexagonal structure. At the same heating temperature, with the increase of holding time, the content of austenite increases gradually, and the hardness difference between austenite and ferrite also increases gradually.