【摘要】 对一种球墨铸铁铸件进行了等温正火处理,分析了其不同等温正火工艺下的布氏硬度和显微组织。结果表明,等温温度一定时,随着正火加热温度的升高,硬度随之升高,当正火加热温度一定时,随着等温温度提高,硬度逐渐降低。正火温度为900℃、等温温度为650℃处理后球铁铸件的显微组织为大量珠光体(>85%)和少量铁素体,硬度较高(375~380 HBS);正火温度较低(850℃)、等温温度较高(700℃)时的显微组织为大量的游离铁素体(>60%)和少量珠光体,硬度较低(200~205 HBS)。根据试验结果提出了一种较为合理的球墨铸铁等温正火工艺。更多还原

【Abstract】 Isothermal normalizing processes were carried out on a ductile iron casting,and the Brinell hardness and microstructure of the ductile iron casting treated after different isothermal normalizing processes were investigated. The results show that when the isothermal temperature is constant,the hardness increases with the increase of normalizing temperature. While the normalizing temperature is constant,the hardness gradually decreases with the increase of isothermal temperature. When the normalizing temperature is higher( 900 ℃) and the isothermal temperature is lower( 650 ℃),the microstructure of the ductile iron treated after isothermal normalizing is consist of a large number of pearlite( > 85%) and a small amount of ferrite,and the hardness is higher( 375-380 HBS). When the normalizing temperature is lower( 850 ℃) and the isothermal temperature is higher( 700 ℃),the microstructure of the ductile iron is consist of a large number of free ferrite( > 60%) and a small amount of pearlite,and the hardness is lower( 200-205 HBS). An optimal isothermal normalizing process for the ductile iron is presented according to the test results.更多还原