【摘要】 用热膨胀测量和热分析方法测定了Nb对灰铸铁共析温度、共晶凝固温度的影响。试验结果表明:(1)在灰铸铁升温过程中,由于富Nb相对C原子的拖曳作用,以及富Nb相降低了渗碳体的溶解速度,从而降低了珠光体向奥氏体转变的温度,提高了铸铁的高温稳定性;(2)在灰铸铁降温过程中,由于晶界处的Nb析出,降低了奥氏体的不稳定性,以及富Nb相中Nb对C原子的拖曳作用,推迟了奥氏体向珠光体转变;(3)Nb降低了灰铸铁的共晶凝固温度。更多还原

【Abstract】 The influence of Nb on the eutectoid temperature and eutectic solidification temperature of gray irons was investigated by using thermal expansion and thermal analysis.The test results showed:(1)During temperature increasing process of the gray irons,since the niobium-rich phase had the traction effect to the C atoms and the Nb-rich phase reduced the dissolution rate of the cementite,the temperature of pearlite transiting to austenite was decreased so that the high temperature stability of the cast irons was increased.(2)During the temperature decreasing process of the gray irons,since precipitation of the niobium at the crystal boundaries decreased the instability of the austenite and the niobium-rich phase had the traction effect to the C atoms,the transition of austenite to pearlite was delayed.(3)Nb decreased the eutectic solidification temperature of the gray irons.更多还原