Invention relates to an autofrettage apparatus (10) for and a method of increasing a fatigue strength a prechamber element (50). The apparatus (10) comprises at least two body parts (20, 30) attachable pressure tight- ly together so as to form a body (203) having a substantially enclosed space (22, 32) therein, wherein a form and dimensions of the enclosed space (22, 31) are chosen so that the prechamber element (50) can be arranged firmly and non-movably inside the body (203) when enclosing the prechamber element (50) by attaching the at least two body parts (20, 30) pressure tightly together, and wherein the body (203) is provided with an at least one conduit (35) opening into the space (22,31) arranged connectable with a fluid source (40) such that an incompressible fluid from the fluid source may be arranged to apply pressure against an inner surface (52) of the prechamber element (50) when enclosed by the body (203), for causing plastic deformation and increasing the fatigue strength of the inner surface layer of the prechamber element (50).
展开▼
