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自增强技术是提高超高压容器与管道疲劳强度与寿命的一种简便方法.所谓自增强,是在容器未使用之前进行超压处理,内壁形成超应变的塑性变形层,而靠近外壁的材料仍保持弹性变形.卸载后,弹性层力图回复原来尺寸而收缩,而内层不回复的塑性变形阻挡了其收缩.结果内层受到外层弹性收缩的压力而产生残余压缩应力,而弹性层则由于收缩受阻碍而产生残余拉伸应力.在工作压力下周向应力沿壁厚分布规律为:内层受拉伸应力,其峰值在内表面,外层受压缩应力.因此,自增强产生的残余应力使工作应力分布趋于均匀,从而使疲劳循环应力的平均应力值下降,超高压容器与管道的疲劳强度与寿命便提高了.
Self-reinforced technology is an easy way to improve the fatigue strength and life span of EHV vessels and pipes.The so-called self-reinforcement is the overpressure treatment of the container before it is used, the inner wall forms an over-strain plastic deformation layer, and the material close to the outer wall remains To maintain the elastic deformation.After unloading, the elastic layer in an attempt to restore the original size and shrinkage, while the inner plastic deformation does not return to stop the contraction of the results of the outer layer by the outer elastic contraction pressure and residual compressive stress, and the elastic layer due to Shrinkage is hindered by the residual tensile stress.When the working pressure is distributed along the wall thickness of the circumferential stress is: the inner layer by the tensile stress, the peak in the inner surface, the outer layer of the compressive stress.Therefore, the residual self-enhancement The stress tends to make the distribution of working stress more uniform, so that the average stress value of fatigue cyclic stress is reduced. The fatigue strength and life span of the ultra-high pressure vessel and pipeline are increased.