ABSTRACT
Residual stresses are imparted in diaphragms usually by metal working operations, and heating or cooling—such as occurs in heat treating or welding operations. Zero drift, span shift, nonlinearity, thermal errors, and reduced endurance limit may all be due to residual stresses. Residual stress determinations are usually made by machining off layers of metal and then measuring deformations. The welding of very thin diaphragms to heavy mounting structures will surely cause residual stresses due to the differential expansion of the parts. Stress on an elastic member has the effect of changing not only the coefficient of expansion but the elastic modulus as well. If high speed and feed are indiscriminately employed, tension stresses at the surface will surely be generated. For long-time stability it is important that the operating stress level on diaphragms be kept well below the material's yield strength.
