Mechanical properties of metals
metals and chemicals are called elements, which are characterized by properties such as good heat conductivity and electric current, opacity, but capable of reflecting light, malleability and ductility.Metals used in virtually all sectors, areas of our lives.Of them make different arrangements, machinery, equipment, tools and even a lot of different things.All metals are separated by the number, nature and content of the alloying particles (components) and purity value.Components are chemical species that may be present in the alloy or metal.Normally, each metal has its own unique features.But to use it to allocate a separate number of properties.These properties are called mechanical.This article will examine the mechanical properties of metals.
notion of mechanical properties of metals
What are the mechanical properties?They describe and explain the ability of a metal to carry out resistance at power factors from the external environment.And accordingly there are numerical indicators, indicating the degree of resistance of a metal.The basic mechanical properties of metals and alloys to date include hardness, toughness, strength, creep, ductility, durability, and toughness.The values of these properties determined during experiments involving the power load on the metal or alloy.And such loads are divided into dynamic, static and re-variables.metal tests are carried out by methods such as stretching, twisting, bending, compression, bending and impact.
strength of the metal alloy strength understand the ability to carry out resistance or metal as an external force factors and internal factors, and thus not to succumb to the strain.If external factors are quite clear, that is,a blow, press, push, then refer to the internal heating or cooling, change in the structure of the substance.
Determination of metal hardness
hardness of metal is its ability to resist or carry out the resistance body, which is much harder.
indentation hardness check methods to test material balls a certain size or a diamond pyramid.The hardness is determined by three indicators, namely, Brinell, Rockwell and Vickers.
Brinell hardness is determined by pressing a steel ball that has a diameter of two millimeters and a half or five or ten millimeters.
to the Rockwell hardness steel ball is pressed or which has a diameter of 1.58 mm or diamond cone that has its apex at the angle of 120 °.There are several values of hardness, namely a very solid, mild steel and hardened steel.For the first type of indentation hardness of diamond cone used to apply the second steel ball, and for the latter taking the form carbide or diamond cone.Rockwell system as a result of shallow dipping diamond cone into the test material allows the metal to explore more accurately than the system Brinell.
As for Vickers hardness determination system is used at its diamond pyramid technique, which has a regular tetrahedral shape.After the metal was exposed to the side of the pyramid, that is, it was immersed into the metal by a certain amount, calculation is performed, starting from the value of the diagonals dents in metal.There's even a special table designed.This method is used to measure the hardness of metal parts having a small cross-section, as well as for surface layers having a greater hardness and a low fineness.
Elasticity, toughness, creep and fatigue
mechanical properties of metals and alloys include well and elasticity.It is understood as the metal's ability to recover its original shape after being stopped by external forces.
Such property as plasticity means the possibility of metal alloy or change their form during load and store has a new shape after the load termination.
Under toughness understand metal property that provides resistance to the action of the shock load.That is, the metal hit some specially harvested material and metal, in turn, maintains or or destroyed.The unit of measurement is the joule per square meter.Under
creep property refers to the ability of metals or alloys change shape slowly and continuously, in other words to deform under load for a long time.
vosnovnom mechanical properties of metals include even such a thing as fatigue, mild or destruction of the metal structure over time with continuous including variable loads.
Each mechanical characteristic has its limit, or a limit, after which comes the destruction of the metal structure.If you need to make a determination of the mechanical properties of metals, and more specifically the parameters of tension, it is necessary to allocate a temporary resistance, a true rupture resistance, and yield.Under the temporary resistance understand the conditional state resistance, which corresponds to a heavy load, after the excessive use of force which will occur the destruction of crystalline metal mesh.The true resistance of the gap is determined as follows: Load fraction divided by the cross sectional area of the metal during the gap, where the gap has occurred.So called yield point load, which is the minimum, and in which the metal starts to deform.This is also called the yield stress of the physical.There is one more yield strength, which is called conditional.It refers to the load at which the tensile metal sample at 0.2 per cent of its length.Apart from these there are other indicators that characterize the mechanical properties of metals and alloys.
In characterizing the strength of proportionality also use the border.This size of a load which gives the deviation of the linear correlation between the magnitude of the load and the amount of elongation and may reach 10-15%.
And the elastic limit is the size of the load at which the deformation occurs.