17-4PH钢加热中的晶粒长大和高温铁素体的析出条件

Grain growth and δ-ferrite precipitation condition in 17-4PH steel during heating process

锻件加热时的晶粒演化和高温铁素体的析出情况决定了锻件的锻造性能。利用箱式真空电阻炉进行加热保温实验,通过设计一系列不同的加热温度和保温时间,研究17-4PH钢的晶粒长大行为,分析不同的加热温度和保温时间对17-4PH钢奥氏体晶粒尺寸的影响,建立晶粒长大模型;通过观察不同温度条件下高温铁素体的形成情况,确定高温铁素体的析出条件。综合晶粒尺寸和高温铁素体形成情况,确定了17-4PH钢的锻造温度。研究表明,从避免高温铁素体形成角度,始锻温度应不超过1200℃;从控制晶粒度角度,始锻温度不超过1175℃。

The grain evolution and the precipitation of δ-ferrite of forgings during heating process have great role in the forging performance.The grain growth behavior of 17-4PH steel was investigated through heating experiments in box resistance furnace through a factorial designing of heating temperatures and holding time,thus the influence of different heating temperature and heat preservation time on the size of austenite grains in 17-4PH steel was analyzed.A mathematical model for grain growth was established,by obsering the formation of δ-ferrlte at different temperatures,the precipitation conditions of δ-ferrite were determined.According to the grain size and formation of δ-ferrite,the forging temperature of 17-4PH steel was determined.The study shows that the forging temperature of 17-4PH steel should not exceed 1200℃ from the aspect of avoiding the formation of δ-ferrite,and not exceed 1175℃ from the aspect of controlling the grain size.