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Category:PDF softwareSurgical steel instruments used in surgery are manufactured and supplied in a variety of forms such as scalpel blades, needles, probes, and cutting instruments. The materials used to construct these surgical instruments are selected to provide the instrument with the requisite characteristics, especially with regard to the blade, so as to provide high strength and a razor sharp edge. An example of such a blade, particularly a razor blade, is found in U.S. Pat. No. 2,923,218.
Razor blades, in particular, are generally made of surgical steel which includes elements which enable a cutting edge to be formed in the blade. It has been found that the strength of the surgical blade is highly dependent upon the direction of deformation which is applied to the surgical steel at the time the blade is formed into the desired shape. Typically, the direction of deformation is the only criterion which governs the final shape of the blade. It is only after the blade has been formed into its final shape that it is cooled. However, the blades made with this technique have an inherent tendency to develop undesired shape distortions. This is a consequence of the inherent properties of surgical steel.
Surgical steel is a very hard metal. Surgical steel has a hardening temperature which is lower than the peak hardness temperature in the hardening range, and generally lowers with increasing temperature. Upon cooling below the peak hardness temperature, the hardening range of the steel is considerably widened. This is due to the formation of carbides in the structure of the steel. Because of the above mentioned characteristics of surgical steel, the blades made from it have the tendency to distort when they are cooled below their peak hardness temperatures. This distortion is undesired and results in a reduced sharpness of the blades. The problem is compounded when the blade is subjected to stresses which are applied during use, especially in medical situations where the blade is used in a confined space.
The general practice of medical operators is to use razors which are cooled to the room temperature when not in use. In most cases the blades are clamped between the slide rails of the razor which results in the blades being cooled for extended periods of time. As is known in the art, when surgical steel is cooled below the peak hardness temperature for a prolonged period of time, the hardening range of the steel is significantly widened. This is also undesirable because it reduces be359ba680
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