ABSTRACT
The underlying principle of an autofrettage process is to subject a thick-walled cylindrical/spherical vessel to a state of partial or full plastic deformation. This chapter presents the theoretical analysis of combining the conventional thermal autofrettage with heat treatment and other frettaging techniques—hydraulic autofrettage and shrink-fitting. It explains the theoretical analysis of thermal autofrettage combined with other frettaging methods. The chapter introduces the microstructure. It also explains alloys and phase diagrams and the phase transformation in steel and its relevance to autofrettage. The chapter describes the concept of the heat treatment coupled with the thermal autofrettage process. In the combined thermal and hydraulic autofrettage process, a thick-walled cylinder was subjected to both a pressure loading and a temperature gradient during the loading step of a typical autofrettage process. This helped in economizing the process in terms of the pressure requirement for a desired level of increase in the pressure-bearing capacity.
