Autofrettage is a metal fabrication method with a wide range of applications, from the manufacture of gun barrels on battleships and tanks to the manufacture of fuel injection systems for diesel engines. Autofrettage is similar in theory to shot blasting.
During metal fabrication, a pressure vessel is subjected to immense pressure, which causes the internal parts of the vessel to yield, thus resulting in internal compressive residual stresses. The purpose of using the autofrettage process is to enhance the durability of the final product, and also increase its resistance to stress corrosion cracking.
自动转向如何工作？
内径小于所得直径的单个钢管用于执行自动逆转法。管子上使用了巨大的压力或自动反向压力，以扩展孔，并将金属的内层拉伸到其弹性极限之外，以使金属不再恢复其原始形状。自动反向压力远大于工作压力。
Despite the extreme internal pressure, the outer layers are not stretched beyond their elastic limit. This is because the stress distribution via the walls of the tube is non-uniform. The change only occurs to the metal adjacent to the source of pressure. As the outer layers are still in their elastic state, they tend to return to their original shape, but this is prevented by the permanently stretched internal layers. Now the stretched internal layers are subjected to low temperature heat treatment causing the elastic limit to be further increased.
如果弯管管道需要自动流动的效果，则必须在弯曲后执行该方法。同样，如果对象有交叉切割，则在执行自动逆转过程时应注意，因为钻孔周围的部分将具有应力浓度并倾向于破裂。但是，由于内部应力将裂纹压在一起，裂纹只会出现到一定长度并停止。为了获得适量的内部压力，必须在短时间内持有自动反应的压力。
下面提到了两个常用的自动转向过程：
- Peening of the surface with metallic or ceramic spheres
- Forcibly inserting a mandrel that is larger than the hole, thus straining the inner material layers.
自动转移的应用和产品
自动转向过程被广泛用于各个行业。为了增加高级工业，汽车，航空航天和防御系统的运行压力，需要使用自动转向过程来改善组件疲劳寿命。
自动旋转还用于增强大炮桶。同样，该过程也用于油气孔中的管状成分向下孔。META是一家位于挪威的石油服务公司，它使用它连接上面概述的密封和强度特性的同心管状组件。
更具体地说，在广大工程领域中，需要自动反向移动过程来通过将永久压缩到其内层来改变容器的内表面。它与用于建筑桥梁的预压混凝土非常相似。
自动转移的好处
自动转换提供以下好处：
- 工作压力，即自动重新解冻的组件可以持有的压力不会增加。例如，管道高达1.8倍，十字架的组件高达2.5倍
- 在“沃勒线”的时间固定区域中，所得压力变化数量的扩散减少
- 在测试中，自动反元素组件的扩散为t <= 1,1，而非自动反应零件一般的扩散为t = 1,3。
- The sensitivity of the notch is greatly reduced.
由于自动转向的集体利益，实现了以下改进：
- 工作压力保持不变 - 壁的厚度减小
- When working pressure remains the same, inexpensive material can be used
- 总体而言有可能增加工作压力
- 可以消除钻孔和表面的饰面
- The service life of a component can be increased at a corresponding working pressure.
来源和进一步阅读
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