Thermal-fatigue of type 304 stainless steel

Thermal fatigue resistance of unrestrained samples of type 304 stainless steel has been investigated under different test conditions. The following studies are reported: (a) effects of heating and cooling rates on the initiation of cracks, (b) effects of upper and lower cycle temperatures on the initiation of cracks, (c) effect of water quenching and (d) the manner in which cracks initiated and propagated. It is shown that under cyclic conditions involving maximum temperatures up to 1000°C, the thermal fatigue life of the material decreases rapidly with rise in the maximum temperature of the cycle. The increase in the lower cycle temperature with constant upper cycle temperature increased the life of the material. But this effect was not as great as was the effect when the peak temperature was reduced by the same amount. The thermal fatigue life decreased as heating and/or cooling rates increased. Water cooling drastically reduced the life of the material --Abstract, page ii