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ASTM standards (material mechanical strength)
- Thread starter Amr Srag
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Chemical composition is just the start point, this determines basic properties at microscopic scale based on atomic link forces, solid solution, precipitation and crystalline structure (ordered arrange of the atoms) by say someone.
Crystalline structure give us the first approximation to macroscopic scale behavior of the material, each type of unitary cell in a crystal have different properties based on the distance between atoms, slip systems, presence and type of solutes (alloy elements and even impurities), by example: Fe alpha (ferrite) crystalizes in BCC system, during heating in a heat treatment, turns in Fe gamma (austenite) and FCC system, this allow that more solute (carbon) can ingress to the crystals of austenite, but whit the accelerated cooling during quenching, all of the solute can't exit from the net promoting the crystallization in a different system, other than ferrite BCC, named Martensite whit BCT system. The stress generated by this forced arrange gives high hardness, low ductility, low toughness to the material, thus the quenched material could be tempered for relax some stresses and obtain the desired properties.
Next step to analyze is polycrystalline materials (most of the utilized in engineering). Be a crystal the minimal unity whit the same atomic arrange and named "grain", in polycrystalline materials, each grain are surrounded by others one, hence grain boundaries exists. Each grain also has imperfections like dislocations. The dislocations as grain boundaries obstacles the slip systems of the crystal, interacts whit crack propagation and defines in part the yield strength of the material.
Grouping and displacement of dislocations (or even others defects) could promote hardness, more or less ductility and UTS by strain hardening, affecting the plasticity, toughness and maximal strength of the material, here chemical composition could play a role in a hardening mechanism by precipitation, the presence of precipitates formed by alloy elements affect also the deformations systems, but the precipitation shall be controlled, fine and homogenous, its regularly achieved by thermomechanical processing of the metal whit controlled rolling for example.
Next step: the texture (organization and orientation) of the microstructure.... mmmm, may be later. In essence, the manufacturing processes modify, orient and / or order the microstructure of the material to favor one or more properties.
The mechanisms are varied, the foundations are extensive and in this brief explanation only some of the many possible ones are mentioned.
I recommend reading introductory texts to the science and engineering of materials, Askeland and Phule has a good one to start.
Crystalline structure give us the first approximation to macroscopic scale behavior of the material, each type of unitary cell in a crystal have different properties based on the distance between atoms, slip systems, presence and type of solutes (alloy elements and even impurities), by example: Fe alpha (ferrite) crystalizes in BCC system, during heating in a heat treatment, turns in Fe gamma (austenite) and FCC system, this allow that more solute (carbon) can ingress to the crystals of austenite, but whit the accelerated cooling during quenching, all of the solute can't exit from the net promoting the crystallization in a different system, other than ferrite BCC, named Martensite whit BCT system. The stress generated by this forced arrange gives high hardness, low ductility, low toughness to the material, thus the quenched material could be tempered for relax some stresses and obtain the desired properties.
Next step to analyze is polycrystalline materials (most of the utilized in engineering). Be a crystal the minimal unity whit the same atomic arrange and named "grain", in polycrystalline materials, each grain are surrounded by others one, hence grain boundaries exists. Each grain also has imperfections like dislocations. The dislocations as grain boundaries obstacles the slip systems of the crystal, interacts whit crack propagation and defines in part the yield strength of the material.
Grouping and displacement of dislocations (or even others defects) could promote hardness, more or less ductility and UTS by strain hardening, affecting the plasticity, toughness and maximal strength of the material, here chemical composition could play a role in a hardening mechanism by precipitation, the presence of precipitates formed by alloy elements affect also the deformations systems, but the precipitation shall be controlled, fine and homogenous, its regularly achieved by thermomechanical processing of the metal whit controlled rolling for example.
Next step: the texture (organization and orientation) of the microstructure.... mmmm, may be later. In essence, the manufacturing processes modify, orient and / or order the microstructure of the material to favor one or more properties.
The mechanisms are varied, the foundations are extensive and in this brief explanation only some of the many possible ones are mentioned.
I recommend reading introductory texts to the science and engineering of materials, Askeland and Phule has a good one to start.
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- #3
thank you for your detailed answer and recommendation, after many comparison between different material specifications in yield and UTS with almost same chemical composition such as (A105-A106-A234-A516-A216)
as conclusion
chemical composition: the main say of material properties with accuracy around 75%
manufacturing method (including essential heat treatment): final say with accuracy around 25%
heat treatment after manufacturing: tuning/stabilize the desired properties previously determined
what is your opinion about the above conclusion?
as conclusion
chemical composition: the main say of material properties with accuracy around 75%
manufacturing method (including essential heat treatment): final say with accuracy around 25%
heat treatment after manufacturing: tuning/stabilize the desired properties previously determined
what is your opinion about the above conclusion?
BeckActuators
Mechanical
Well to start with the strengths there are multiple strength factor that needs to keep in mind while increasing overall strength of the material. Like if you want to increase the tensile strength you need to increase the dislocation density. Like for high dislocation density high shear stress is required to move the dislocation, so it increases the tensile strength. But for low dislocation densities like 10[sup]7[/sup] to 10[sup]9[/sup]dislocations/m[sup]2[/sup] will result in low tensile strength.
As far as your conclusion is concerned I will say that 70% is the part of material's chemical competition that play part in the strength. 30% is the manufacturing and post heat treatment of the material that enhances the pre existing strengths. Heat treatmenst not only tune or stablize but they also enhance the strengths of the materials
Electric Actuator You Can Depend On
As far as your conclusion is concerned I will say that 70% is the part of material's chemical competition that play part in the strength. 30% is the manufacturing and post heat treatment of the material that enhances the pre existing strengths. Heat treatmenst not only tune or stablize but they also enhance the strengths of the materials
Electric Actuator You Can Depend On
EdStainless
Materials
In material with high strain hardening rates such as stainless steels processing can be everything.
I can anneal an alloy and have UTS/Yld of 100ksi/40ksi and cold work it to 200ksi/180ksi.
Of course in the process the elongation will drop from 60% to 4%.
We sell SS tube at a range of strength levels, and the same applies to cold worked strip and wire.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
I can anneal an alloy and have UTS/Yld of 100ksi/40ksi and cold work it to 200ksi/180ksi.
Of course in the process the elongation will drop from 60% to 4%.
We sell SS tube at a range of strength levels, and the same applies to cold worked strip and wire.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
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