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 材料的疲劳过程是能量耗散的过程，在宏观上表现为热耗散，能量理论是研究材料疲劳行为微观机理和宏观现象的桥梁。文中利用红外热像仪对具有颈缩部分的45号钢试件疲劳过程中的温度变化进行了研究，探讨了影响温度变化的机制，并介绍了快速确定45号钢疲劳极限的方法。实验结果表明，该方法所测得的疲劳极限合理，且该方法具有非接触、便捷、低成本等优点。

Experimental Method of High-speed Determination of Fatigue Limit for 45 Steel

The materials’ fatigue process is one of energy dissipation, which is presented as the heat dissipation on the macroscopy. The energy theory which is applied in the study of materials’ fatigue behavior is a bridge between micro mechanism and macro phenomenon. In this paper, the infrared thermal sensor is utilized to study the temperature changes during the fatigue test of the 45# steel specimen with necking part, and the mechanism of temperature change has been discussed, and a new method to determine the fatigue limit of 45# steel fast is introduced. The experiment indicates that the result of 45# steel’s fatigue limit from infrared thermography technique is reasonable, and this method has such merits as non contact, convenience and low cost.