Abstract: A low alloy rotor steel is described which is substantially free of temper embrittlement within given constraints. In addition to describing the chemical composition there is included equations for predetermining the fracture appearance transition temperature of the unembrittled steel which equation permits the manufacturer to balance the alloying components within the ranges given in order to obtain a predetermined fracture appearance transition temperature, and by further balancing of the alloying components, the change in the fracture appearance transition temperature can be controlled to within .+-. 40F.degree.. Drawings are included which graphically depict the area for control of the critical relationship between the molybdenum and the chromium.

Abstract: A specimen or in-service structural member in which strain is to be measured is fabricated as a unit which generates a signal in response to strain occurring in a given region of its surface. A film of piezoelectric material is deposited upon the surface in a manner providing a strong molecular bond between the specimen or member and the piezoelectric film. The film material is chosen from the class having a 6 mm type crystal lattice structure and is formed as a crystalline deposit with the c-axis perpendicular to the surface of the specimen or member. An arrangement of electrodes is provided for direct electrical coupling between spatially separated portions of the piezoelectric film. The electrodes form an output coupling for an electrical signal generated by the piezoelectrically active properties of the piezoelectric film in response to strain mechanically coupled from the substrate surface to the piezoelectric film through the molecular bond.