METHOD FOR METALLURGICAL ENHANCEMENT OF A FAILED BOLT HOLE

摘要

A method for metallurgical enhancement of a failed bolt hole, or stud attachment, providing for replacement of service induced failed material from the female threaded area of the bolt hole. A method in accordance with the present invention is particularly suited for power plant equipment, such as a steam turbine. Failed material from the female threaded area is removed and filler metal is arc welded to the exposed base metal of the hole using a mechanized gas tungsten arc weld device employing a continuous spiral weld bead. Proper selection of the filler metal, considering the base metal to which it is applied and, moreover, the type of failure which the base metal o! the hole has been experiencing, provides for improved structural integrity of the mechanical joint and increased service life of the associated steam turbine apparatus. Weld tempering of the filler metal reduces undesirable weakening of the weld metal in the heat affected zone, thus providing further metallurgical enhancement of the failed bolt hole.