Gleem – a New Composite Gun Tube Processing Technology

The development of a process to emplace a refractory metal liner inside a gun tube is described. The process consists of filling the liner with an elastomeric material and then slipping this arrangement into the gun tube. The ends of the liner are plugged with plastic disks and pressure is applied to the elastomeric material by a load frame. The original clearance between the liner and gun tube is small, so the action of the pressure expands the liner slightly until it contacts the steel gun tube wall. At that point, greater pressure can produce residual internal stresses within the steel gun tube. Pressures in excess of 250 ksi have been achieved with this simple arrangement. The stresses provide an autofrettage to the steel tube as well as forces retaining the liner inside the tube. Initial efforts have resulted in bond strengths over 3 ksi. In addition, by tailoring the degree of lubrication between the elastomeric material and the liner, a graded autofrettage can be produced in the steel gun tube.