Uncovering fracture models for adva

Uncovering fracture models for advanced, high-strength steels

Steel is one of the most common structural materials, truly one of the foundations of modern civilization. An alloy of iron and carbon, steel has been made since biblical times. With two thousand years of experience in steelmaking, it would seem all there is to know about steel would already be known. But for Allison Beese, McFarlane Assistant Professor in Materials Science and Engineering, the secret world of steel is still unfolding.

"There is a lot known about traditional steels, but advanced, high-strength steels are a different story," says Beese. "Traditional fracture models don't accurately predict the properties of these advanced steels. We're still trying to understand the mechanisms for damage accumulation and fracture, and steel companies are very interested in developing other designs for steel."

The best steels have high strength in conjunction with ductility, the ability to be stretched. Alloying small amounts of materials such as manganese can add to a steel's strength, while phase transformations during processing or deformation can change the steel from soft to extremely hard and strong.

For most of the history of steelmaking, metalworkers found out through trial and error how to produce steel with the qualities they wanted. They had no knowledge of "microstructure;" they just knew that certain ingredients and procedures worked.
One of the most famous steels ever made, called Damascus steel, was highly valued in ancient and medieval times for its strength, flexibility, and ability to hold an extremely sharp edge—traits that made it the material of choice for the production of swords and knives. (The vaunted Valyrian steel in the novel series and TV show Game of Thrones reportedly was modeled on Damascus steel.) The source of its unique qualities was a mystery until 2006, when a German research team found that a centuries-old blade of Damascus steel contains carbon nanotubes and cementite (iron carbide) nanowires, which must have been created during the forging process—a process whose details were lost in the late 1700s and have yet to be re-discovered.
Beese studies similar relationships between fine structure and overall characteristics, with an eye toward identifying what conditions will produce the features needed for different applications.
"I am primarily an experimentalist in trying to understand the connection between microstructure and macroscopic mechanical behavior," she says. "Through the understanding of deformation mechanisms, we can then develop predictive models."
In one kind of experiment, Beese and her students stretch pieces of high-strength stainless steel and use digital image correlation to quantify the resulting deformations. They first spray-paint a speckled pattern on the sample. Then, as a test machine pulls on the sample, a camera shooting at one-second intervals captures changes in the speckle pattern. Analysis of those changes reveals where, how much, and how fast the steel deforms.
Beese's group has been testing relatively large components, or walls, of an additively manufactured nickel superalloy, a stainless steel, and a titanium alloy. By carving out small samples from the walls, her group can measure the material's mechanical properties as a function of the location and direction of the layers. They have found that ductility depends on the direction of the build, while strength varies with height within the structure.

Kết quả (Anh) 1:

Uncovering fracture models for advanced, high-strength steelsSteel is one of the most common structural materials, truly one of the foundations of modern civilization. An alloy of iron and carbon, steel has been made since biblical times. With two thousand years of experience in steelmaking, it would seem all there is to know about steel would already be known. But for Allison Beese properties, McFarlane Assistant Professor in Materials Science and Engineering, the secret world of steel is still unfolding."There is a lot known about traditional steels, but advanced, high-strength steels are a different story," says Beese properties. "Traditional fracture models don't accurately predict the properties of these advanced steels. We're still trying to understand the mechanisms for damage accumulation and fracture, and steel companies are very interested in developing other designs for steel. "The best steels have high strength in conjunction with ductility, the ability to be stretched. Alloying with small amounts of materials such as manganese can add to a steel's strength, while phase transformations during processing or deformation can change the steel from soft to extremely hard and strong.For most of the history of steelmaking, metalworkers found out through trial and error how to produce steel with the qualities they wanted. They had no knowledge of "microstructure;" they just knew that certain ingredients and procedures worked.One of the most famous steels ever made, called Damascus steel, was highly valued in ancient and medieval times for its strength, flexibility, and ability to hold an extremely sharp edge — traits that made it the material of choice for the production of swords and knives. (The vaunted Valyrian steel in the novel series and TV show Game of Thrones reportedly was modeled on Damascus steel.) The source of its unique qualities was a mystery until 2006, when a German research team found that a centuries-old blade of Damascus steel contains carbon nanotubes and cementite (iron carbide) nanowires, which must have been created during the forging process — a process whose details were lost in the late 1700s and have yet to be discovered.Beese properties studies similar relationships between fine structure and overall characteristics, with an eye toward identifying what conditions will produce the features needed for different applications."I am primarily an experimentalist in trying to understand the connection between microstructure and macroscopic mechanical behavior," she says. "Through the understanding of deformation mechanisms, we can then develop predictive models."In one kind of experiment, Beese properties and her students stretch pieces of high-strength stainless steel and use digital image correlation to quantify the resulting deformations. They first spray-paint a speckled pattern on the sample. Then, as a test machine pulls on the sample, a camera shooting at one-second intervals captures changes in the speckle pattern. Analysis of those changes reveals where, how much, and how fast the steel deforms.Beese's group has been testing relatively large components, or walls, of an additively manufactured nickel superalloy, stainless steel, and a titanium alloy. By carving out small samples from the walls, her group can measure the material's mechanical properties as a function of the location and direction of the layers. They have found that ductility depends on the direction of the build, while strength varies with height within the structure.

Kết quả (Anh) 2:

Fracture uncovering models for advanced, high-strength steels Steel is one of the Most Common structural materials, truly one of the foundations of modern civilization. An alloy of iron and carbon, steel made ​​since Biblical times Đã. With two thousand years of experience printing steelmaking, it would Seem all there is to know about steel would already be known. But for Allison Beese, Assistant Professor McFarlane print Materials Science and Engineering, the secret world of steel is still unfolding. "There is a lot known about traditional steels, but advanced, high-strength steels are a different story," says Beese. "Traditional models do not accurately predict Fracture the properties of những advanced steels. We're still thử hiểu the accumulation and Fracture Mechanisms for damage, and steel companies are very interested Developing other print designs for steel." The best steels have high print conjunction with ductility strength, the ability to be stretched. Alloying small tiền of materials như manganese can add to a steel's strength, while phase transformations khi processing or deformation can change the steel from soft to extremely hard and strong. For Most of the history of steelmaking, metalworkers found out through trial and error how to Produce Steel with the qualities chúng wanted. They Had no knowledge of "microstructure;" They just Knew That Certain ingredients and Procedures worked. One of the Most Ever made ​​famous steels, gọi Damascus steel, was highly ancient and medieval times printing Valued for its strength, flexibility, and ability to hold an extremely sharp edge-traits that made ​​it the material of choice for the production of swords and knives. (The vaunted Valyrian steel in the novel series and TV show Game of Thrones was reportedly modeled on Damascus steel.) The source of its unique qualities was a mystery off until 2006, the German research team found khi có a centuries-old blade of Damascus steel contains carbon nanotubes and cementite (iron carbide) nanowires, mà được must have created the forging process khi có-a process details in the late 1700s là lost and have yet to be re-Discovered. Beese similar studies giữa fine structure and overall relationships đặc , with an eye Toward Identifying what will tạo the features needed conditionsEND_SPAN for khác applications. "I am an experimentalist chính thử hiểu print microstructure and macroscopic giữa the connection mechanical behavior," She says. "Through the understanding of Deformation Mechanisms, then develop predictive models WE CAN." In one kind of experiment, Beese and her Artist Students stretch pieces of high-strength stainless steel and use digital image correlation to quantify the quả deformations. They spray-paint a Speckled first pattern on the sample. Then, as a test machine pulls on the sample, a camera at one-second intervals Shooting captures changes in the speckle pattern. Analysis of changes những reveals where, how much, and how fast the steel deforms. Beese's group Đã Relatively large testing components, or walls, of an additively manufactured nickel superalloy, a stainless steel, titanium alloy and a. By carving out small samples from the walls, the her group can measure the material's mechanical properties as a function of the location and direction of the layers. They have found mà ductility depends on the direction of the build, while strength varies with height trong structure.