Is the development of science and technology, mathematics, physics, chemistry progress directly, at the same time, the humanities, language, the best play.
Said physics, said the mechanics, see mechanics from cold water unit, to summarize the physical characteristics into full play.
in general engineering technology, carbon steel is one of the most widely used structural materials, but unfortunately it is the most obvious disadvantage is that the mechanical properties of low temperature brittleness.
Not all metals have this low temperature brittleness, most of the non-ferrous metal material as the temperature drops, its yield strength, tensile strength, hardness and fatigue resistance improved instead, that is, instead of the mechanical properties of the metal material at low temperature is better than when the room temperature.
was elected with low temperature metal structure material, mainly is the attention to the problem of low temperature brittleness and strength, especially the brittleness problem.
Usually keep malleable face-centered cubic metal at low temperature, while the metal body centered cubic structure brittle at low temperatures.
in the design of the experiment device of low temperature and often have sharp corners, turn place such as welding and cold processing problems, and these places where stress is concentrated.
For malleable metal part can be eliminated by plastic deformation to stress concentration, thus reducing the material fracture, for brittle metal, because of its plastic deformation is small, do not eliminate the stress concentration and brittle fracture is often happened.
common face-centered cubic metal at low temperature, its yield strength with temperature don't changed.
In the design of the low temperature device, the maximum allowable stress of material cannot exceed the tensile strength, the general should be less than the yield strength of material.
Such as according to the material yield strength or tensile strength at room temperature for design, and after the experiment at room temperature, the thing is not a problem at low temperature applications.
