Hardware mechanical properties
Mechanical properties are the characteristics of the metal material under the action of external force.
1, strength: material in the external force (load), the ability to resist deformation and fracture. Material per unit area subject to load.
2, yield point (c s): says the yield strength, refers to the material in the stretching process, the material stress reaches a critical value, load no longer increases deformation continues to increase or 0.2%L stress value, in units of Newton / mm 2 (n / mm2) said.
3, the tensile strength (o b) is also called the ultimate strength under tensile material before the maximum stress. The unit is represented by Newton / mm 2 (N/mm2).
4. Elongation (delta): the percentage of the total elongation and the length of the original mark after tensile fracture.
5, section shrinkage (only) in the tensile fracture after, the largest section area and the original narrow basal area percentage.
6, hardness: refers to the material resistance to other more hard material of the surface of the ability, commonly used in the range of hardness to determine the distribution of hardness (HBS, HBW) and HKA (HKB, HRC).
7, impact toughness (Ak): material resistance to impact load capacity, the unit is Joule / cm 2 (J/cm2).
Tensile stress and phase
1, e=: epsilon Sigma e/E, elastic index. E, E
2, rigid: Delta L=P - l/E - F strength elastic deformation resistance
3, strength: sigma Sigma b--- s--- yield strength, tensile strength
4, toughness: impact absorption work Ak
5, the fatigue strength of alternating load: O -1< o s
6, hardness HR, HV, HB
A. I stages: linear elastic stage, the initial tension, stress-strain curve is a straight line, this stage should be a maximum limit of force called the proportional limit of the material sigma E.
B. second stage: yield stage, when the stress is increased to a certain value, stress-strain curve of horizontal line segments (small variation), in this stage, stress is almost unchanged, while the deformation is rising sharply, material loses its ability to resist deformation, this phenomenon known as yield, the stress that yield stress or yield limit, and represented by sigma S.
C. stage: in order to strengthen the stage, after the yield, the material has increased the ability to resist deformation. The stress of the highest point in the strengthening phase, the strength of the material is the ultimate strength of the material. With a B, the ultimate strength is the maximum stress material can withstand.
D. stage IV: neck shrinkage stage when stress has increased to maximum sigma B, pieces of a local significant contraction, the last in the necking fracture.
For low carbon steel s and a sigma B as the main index to measure the strength of the. Rigid: Delta L=P - l/E - F, the ability to resist deformation. P--- pulling force, l--- material, E--- modulus, F--- section area.
