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Effect of Elevated testing on Properties of Metallic Samples
Testing steel samples at high temperatures is a crucial component of materials science and engineering. It aids in figuring out how materials behave and function when exposed to high temperatures, which is crucial for a variety of applications including chemical processing, aerospace, automotive, and power generation. Testing at elevated temperatures can show how temperature affects the mechanical characteristics of ferrous materials. Among the major effects are:
- Tensile strength and yield strength: The tensile strength and yield strength of the majority of mechanical materials tend to decline as the temperature rises. The reason for this is that as atoms vibrate more thermally, their susceptibility to dislocation motion and plastic deformation decreases. Certain superalloys, for example, retain their strength at high temperatures as a result of solid-solution strengthening and precipitation-hardening mechanisms. However, some materials may display different behaviour.
- Ductility: Testing metallic materials at high temperatures frequently shows an increase in their ductility. The material can deform plastically to a larger extent before failing at higher temperatures because dislocation motion is easier to facilitate at these temperatures. Applications needing high-temperature deformability, like hot-forming processes, benefit from this increased ductility.
- Stress rupture and creep: Under sustained pressure at a high temperature, creep is the time-dependent deformation of a material. Testing at elevated temperatures can be used to analyze ferrous materials’ creep behaviour and stress rupture life. Creep rates and stress rupture life usually deteriorate as the temperature rises. This is an important factor to take into account for uses like gas turbines and nuclear reactors that require prolonged exposure to elevated temperatures.
- Fatigue: At high temperatures, a material’s ability to withstand cyclic loads or fatigue resistance, is usually reduced. High temperatures can hasten the development and growth of fatigue cracks due to enhanced atomic mobility. Furthermore, fatigue fracture propagation may be exacerbated by high temperatures’ increased ductility and decreased strength.
- Thermal expansion: When exposed to high temperatures, metallic materials typically show a rise in their dimensions. This tendency can be measured using the coefficient of thermal expansion (CTE). Designing components that must maintain dimensional stability and prevent thermal stresses when subjected to temperature fluctuations requires an understanding of the CTE.
- Oxidation and Corrosion: Testing at elevated temperatures can also show whether ferrous materials are susceptible to oxidation and corrosion. The reaction rates of oxidation and corrosion usually increase at high temperatures, which can result in a loss of mechanical properties and the development of surface layers that could jeopardize structural integrity.
Anil K Vashishta
Anil K Vashishta is a Metallurgical Engineer from the National Institute of Technology, Rourkela, with over 29 years of expertise in materials, corrosion, and metallurgical/mechanical laboratory management. As the Managing Director of Colossal Consultants LLC in the United Arab Emirates—founded in 2019 to serve the GCC and South-Eastern regions—Anil applies his extensive background to support diverse industries, particularly oil and gas.
A Certified NACE Corrosion Specialist and NACE Material Selection Design Specialist, Anil specializes in corrosion assessment and mitigation, material selection, turnkey laboratory setup, and root cause/failure analysis. His comprehensive skills also include in-situ replica metallography, condition assessment, coating evaluations, and cathodic protection. With a deep passion for technical excellence and practical solutions, Anil continues to drive innovation and best practices in the field of materials engineering.
