应力的消除.PDF

應力的消除 142 Stress By Daniel H. Herring Stress relief is a heat treatment process that relies on slow cooling to achieve its desired effect, and is influenced by a number of factors including the internal stress induced into the Relief parts from the various manufacturing methods (e.g. bending, shearing, forging, sawing, machining, grinding, milling, turning, welding, etc.) and prior processing. The application end use How Do We Perform a Stress Relief ultimately defines the allowable stress state. So how does one perform a stress relief operation? Operation? For carbon steels, stress relief operations are Processes which depend on slow cooling (e.g. annealing, typically performed at 40℃ (105℉) - 75℃ (165℉) below normalizing, stress relief ) do so for a number of reasons; to the lower critical temperature, that is in the range of relieve stresses, improve chemical homogeneity, soften a material for subsequent operations (e.g. machining), refine grain 500℃ (930 ℉) - 650 ℃ (1200 ℉). It is also important to understand that the elimination of stress is not size and for such reasons as embrittlement relief or magnetic properties[1]. As a general rule, the larger or more complex the instantaneous, being a function of both temperature and time for maximum benefit. Typically one (1) hour part, the greater the amount of internal stress present.