用热分析法测定低合金灰铸铁的抗拉强度和硬度

Using Thermal Analysis to Determine Tensile Strength and Hardness of Low Alloyed Gray lron

用 TCS热分析法测定低合金灰铸铁的抗拉强度和硬度，对铁液延长保温时间，可出现如下现象： 1)抗拉强度和硬度瞬时下降后又明显上升： 2)碳、硅含量较高时可用延长过热时间的方法提高抗拉强度和硬度； 3)铁液经过过热，铸态石墨长度由 10～ 20μ m缩短到 2μ m左右； 4)在碳、硅含量较低时白口范围增加 (激冷层加厚 )尤为显著； 5)白口共晶温度 Tec和孕育共晶温度 Teg几乎不随过热时间变化，但实际共晶温度 Teo则向白口共晶温度 Tec侧下降； 6)用初晶温度求得的 CE值和由共晶温度求得的△ T1 /△ T3作为自变量，把抗拉强度、硬度以及石墨长度作为因变量，可得到一套完整的回归方程式，即用 TCS热分析法来测定铁液状态的低合金灰铸铁抗拉强度和硬度是完全可能的。

The TCS thermal analysis was adopted to determine the tensile strength and hardness of low－ alloyed gray iron.Lengthening holding time of the molten iron would cause:(1)After a momentary decreasing the tensile strength and hardness increased obviously again;(2)When carbon and silicon content were relatively high the tensile strength and hardness could be increased by lengthening superheating time;(3)As a result of superheating of the molten iron,the length of as－ cast graphite was shorten from 10～ 20μ m to about 2μ m;(4)Chill width range was enlarged(chilled layer became thicker)especially remarkably when the carbon and silicon content was relatively lower;(5)Eutectic temperature of white iron Tec and eutectic temperature of inoculated iron Teg almost didn't change with the changing of superheating time,however the practical eutectic temperature Teo has decreased towards the side of the eutectic temperature of white iron Tec;(6)With the CE value obtained from the temperature of primary crystallization and the△ T1 /△ T3 obtained from the eutectic temperature as the independent variables,and the tensile strength,hardness and graphite length as dependent variables,a complete set of regress equations could be obtained,so that it was very possible to use TCS thermal analysis to determine the tensile strength and hardness at the liquid stage of the cast iron.