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采用膨胀法并结合金相-硬度法,在DIL805L热膨胀仪上测定了弹簧钢38Si7在不同冷却速度下的膨胀曲线,获得其奥氏体连续冷却转变曲线(CCT)。结果表明,Si、Cr、Mn等元素的加入抑制了弹簧钢38Si7的贝氏体转变,同时扩大α相区,使得可以在较宽范围内获得铁素体组织,且任何冷却过程不会获得贝氏体组织。当冷速大于15℃/s时,得到马氏体+珠光体+铁素体混合组织。冷速大于60℃/s时,能得到马氏体+铁素体组织。随冷速增加,冷却后组织逐渐细化,硬度增加。
The expansion curve of the spring steel 38Si7 at different cooling rates was measured on the DIL805L dilatometer by means of expansion method combined with the metallographic - hardness method to obtain the austenite continuous cooling transformation curve (CCT). The results show that the addition of Si, Cr, Mn and other elements inhibits the bainite transformation of the spring steel 38Si7 and enlarges the α-phase region so that the ferrite structure can be obtained in a wide range, and no cooling is obtained for any of the cooling processes Tissue. When the cooling rate is more than 15 ℃ / s, martensite + pearlite + ferrite mixed structure is obtained. Cooling rate greater than 60 ℃ / s, martensite + ferrite can be obtained. With the cooling rate increases, the organization gradually cooling after cooling, increasing the hardness.