Study on Thermal Physical Properties of 304 Stainless Steel at High Temperature

The DIL402Cthermal dilatometer and STA449Cthermal analyzer were employed to test the linear expansion and contraction coefficient,specific heat cpand DSC curve of 304stainless steel.The result shows that the range of linear expansion coefficient was 20.970 0×10-6~21.571 2×10-6 K-1 during heating and the range of linear contraction coefficient was 21.252 8×10-6~21.947 1×10-6 K-1 during cooling.The linear expansion and contraction coefficient were higher than other materials,so the 304stainless steel belong to the crack sensitive steel.The curve of cposcillates obviously during the 900~1 400℃as temperature raise.Because of the transformation of crystalline shape occurs,the defects of casting blank occur easily.A endothermic peak exists obviously at 1 420.8℃during the DSC test.The sample began to melt at 1 420.8℃and the peak temperature was 1 438.86℃in the heating step.The sample began to solidify at 1 439℃and the peak temperature was 1 435.6℃in the cooling step.During the 1 439~ 1 100℃as temperature fell,the curve of DSC was unsmooth,the thermostability was bad and phase change occurs. These factors cause the initial solidified shell non-homogeneous.These temperature points belong to the upper of crystallizer,so the casting blank causes crackle easily during this temperature range.