Mechanical properties refer to the characteristics of metallic materials under external force.
1, strength: material in the external force (load) under the action of resistance to deformation and fracture. Nominal stress per unit area of material.
2, the yield point (o s) said: the yield strength refers to the material in the stretching process, the stress reaches a critical value, the load value no longer increases the stress and deformation continues to increase or 0.2%L, unit by 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. Units are expressed in Newtons / mm 2 (N/mm2).
4 elongation: the percentage of total elongation to the original gauge length after tensile fracture.
The 5 section shrinkage (PSI) material in tensile fracture, the largest section area and the original narrow basal area percentage.
6 hardness: refers to the material resistance to other hard material pressure on the surface of the ability, commonly used hardness according to its range measured distribution hardness (HBS, HBW) and Rockwell hardness (HKA, HKB, HRC).
7, impact toughness (Ak): material resistance to impact load capacity, unit of Joule / cm 2 (J/cm2).
Tensile stress and stage
1, elasticity: epsilon e=, sigma e/E, index sigma e, E
2, rigid: Delta L=P - l/E - F strength elastic deformation resistance
3 strength: Sigma s--- yield strength, sigma b--- tensile strength
4, toughness: impact absorption work Ak
5 fatigue strength: alternating load Sigma -1< sigma S
6, hardness HR, HV, HB
A. I stage: linear elastic stage, at the initial stage of tension, the stress-strain curve is a straight line. At this stage, the maximum stress limit is called the limit of proportionality E.
B. II stage: the yield stage, when the stress increases to a certain value, the stress-strain curves of horizontal lines appear (with small fluctuations). In this stage, the stress and deformation is almost unchanged, the rapid growth of material, lose the ability to resist deformation. This phenomenon is known to yield, the corresponding stress is called the yield stress and yield limit, and is represented by a s.
C. III stage: in order to strengthen the stage, after yielding, the material also increases the ability to resist deformation. The stress corresponding to the highest point of the strengthening stage is called the strength limit of the material. The strength limit is the maximum stress that a material can bear, with the sigma B.
D. IV stage: necking, and when stress increases to maximum B, a part of the specimen shrinks significantly, and finally breaks at the necking.
For low carbon steel, sigma S and sigma B are the main indexes to measure its strength. Rigid: Delta L=P - l/E - F, the ability to resist deformation. P--- tensile force, l--- material length, E--- elastic modulus, F--- section area.
Of the performance of materials subjected to a variety of processing and processing capabilities.
Casting performance: refers to the number of process performance of metal or alloy is suitable for casting, including flow performance, full mold shrinkage, ability; ability of casting shrinkage; segregation refers to chemical composition heterogeneity.
Weldability: refers to the metal material by heating or heating and pressure welding method, the two or more than two metal materials welded together, the interface can meet the purpose of use of characteristics.
Top gas section performance: refers to the metal material can withstand the top forge not to break the performance.
Cold bending property: refers to the metal material can bear the bending at ordinary temperature, but does not break the performance. With the bending degree of the bending angle alpha (general angle) or bending center diameter of D on the thickness of the material ratio of a, a or d/a is smaller, the better cold resistance material.
Stamping performance: the metal material can withstand the stamping deformation without breaking. Punching at room temperature is called cold stamping. The test method was tested by cupping test.
Forging performance: the ability of metal material to withstand plastic deformation without breaking during forging.
The resistance of metals to chemical or electrochemical reactions when they are swept in contact with the surrounding medium.
Corrosion resistance: refers to the ability of metal materials to resist various mediums.
Oxidation resistance: refers to the metal material in the high temperature, resists produces the oxidation skin ability.
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