Mechanical properties of metal materials and heat treatment process
Mechanical properties of metal materials and heat treatment process （1） "Four Elements" of Materials Science and Engineering Exploring the relationship between these four elements covers all research in the fields of materials science and engineering. It is the ability of engineering and technical personnel to be able to select appropriate materials according to the performance requirements and formulate corresponding processing techniques so that they will eventually have properties that meet the performance requirements. Mechanical properties of materials The mechanical properties of the material refer to the behavior under the action of an applied load (external force) or a combination of load and environmental factors (temperature, medium, and loading rate). 1111MicrosoftInternetExplorer402DocumentNotSpecified7.8 磅Normal0 Mechanical properties of metalCommonly used mechanical performance index of metalStrengthYield strength, tensile strength, fracture strengthPlasticityPercentage elongation,reduction of area, work-hardening exponentialSpringinesselasticity modulus,elastic limit,proportional limitHardnessBH, Vickers hardness,Rockwell hardnessToughnessstatic toughness, impact toughness, fracture toughnessFatiguefatigue strength, fatigue life, fatigue notch sensitivityStress corrosionStress corrosion critical stress field intensity factor,Stress corrosion cracking rate Unidirectional static tensile stress of MS--- stress-strain curve Stress-strain curve 1、 oa part， elastic deformation2、 abpart：elastic deformation +Plastic Deformation3、 bcd part：the material has obvious plastic deformation,under the condition that the force is basically unchanged, the sample continues to elongate4、 dB part：Elastic deformation + uniform plastic deformation5、Point B, the phenomenon of neck shrinkage occurs, the local section of the sample obviously reduces the bearing capacity of the sample, the tensile force reaches the maximum value, and the sample is about to fracture. Strength index 1. Strength refers to the ability of a material to resist plastic deformation and fracture。Yield StrengthΔs= Fs/SoFs: The tensile force that the sample bears when yielding (N)So: Original cross-sectional area of the sample (mm)Δs: The resistance of the material to obvious deformation is one of the main basis for the design and selection of tough materials.2. Tensile strengthThe maximum tensile stress that the specimen withstands before breaking off reflects the resistance of the material to the largest uniform deformation.Δb=Fb/SoΔb is often used as a seat for brittle materials and as a basis for design.