析出相对塑料模具钢LJ338ESR腐蚀性能的影响

利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、硬度仪、电化学分析仪,研究了塑料模具钢LJ338ESR经不同固溶和时效温度处理后的组织、硬度和腐蚀性能变化。结果表明,固溶温度为1 000～1 090℃时,随固溶温度上升,合金元素及NbC更多地溶入基体中,使得组织的均匀性增加,水冷后马氏体量增加,导致硬度上升,而耐蚀性能增强。时效温度为300～450℃时,随温度上升,细小富Cu相形核并与基体形成共格bcc结构,共格应变能逐渐增大,导致硬度上升,而耐蚀性能减弱;当时效温度为450～600℃时,随温度上升,富Cu相逐渐由共格过渡到非共格态,共格应变能降低,导致硬度下降,而耐蚀性能增强。600℃形成的逆变奥氏体进一步提高了耐蚀性。

Effect of Precipitation Phases on Corrosion Performance of Mold Steel LJ338ESR for Plastics

The microstructure, hardness and corrosion resistance of mold steel U338ESR for plastics treated at various solution and aging temperatures, were investigated by means of optical microscope (OM) , scanning electron microscope (SEM) , transmission electron microscope (TEM) , hardness tester and electrochemical analyzer. The results showed that with the increase of solution temperatures, which were at the range of 1 000 ~ 1 090 °C , alloying elements and NbC dissolved more into matrix, the uniformity of microstructures and the amount of martensite increased after water cooling, leading to the increase of hardness and the enhancement of corrosion resistance. When the aging temperatures were at the range of 300 -450 °C ，with the increase of temperatures, small Cu-rich phases nucleated and formed coherent bcc structure with the matrix and the coherent strain energy increased gradually, resulting in the increase of hardness and the decrease of corrosion resistance ； when the aging temperatures were at the range of 450 〜600°C , with the increase of temperatures, the Cu-rich phases transferred from coherent to incoherent state gradually, the coherent strain energy decreased, resulting in the decrease of hardness and the enhancement of the corrosion resistance. Reversed austenite formed at 600 °C, enhanced corrosion resistance further.