[Moving Equipment Technology Exchange Edition] Daily Question [Moving Equipment] 20190701

The phenomenon in which metal materials undergo slow plastic deformation under constant temperature and constant stress over a long period of time is known as creep. For ordinary metals, the phenomenon of creep becomes apparent only under high-temperature conditions. However, certain metals, such as lead, tin, and their alloys, can also exhibit creep behavior at room temperature. The stress required to induce creep can be even less than the material’s elastic limit. The occurrence of creep is determined by three factors: temperature, stress, and time. Carbon steel exhibits significant creep under stress at temperatures of 300–400°C. When the temperature is above 400°C, significant creep occurs at a high rate even with low stress. When the temperature of alloy steel exceeds 400–450°C, creep occurs under certain stress; the higher the temperature, the more pronounced the creep phenomenon becomes. There are many components in high-temperature and high-pressure thermal power plants that are prone to creep, such as main steam pipes, boiler headers, steam piping, high-temperature fasteners, and turbine cylinders. Due to the accumulation of metal creep, metal components may undergo excessive plastic deformation and become unusable, or creep may enter an accelerated phase leading to creep rupture; in either case, the components will fail and be damaged, potentially even causing serious accidents. Therefore, strict creep monitoring is required for high-temperature components that operate over long periods of time. Of course, some plastic deformation of certain components during operation is acceptable

The phenomenon in which metal materials undergo slow plastic deformation under constant temperature and constant stress over a long period of time is known as creep. For ordinary metals, the phenomenon of creep becomes apparent only under high-temperature conditions. However, certain metals, such as lead, tin, and their alloys, can also exhibit creep behavior at room temperature. The stress required to induce creep can be even less than the material’s elastic limit. The occurrence of creep is determined by three factors: temperature, stress, and time. Carbon steel exhibits significant creep under stress at temperatures of 300–400°C. When the temperature is above 400°C, significant creep occurs at a high rate even with low stress. When the temperature of alloy steel exceeds 400–450°C, creep occurs under certain stress; the higher the temperature, the more pronounced the creep phenomenon becomes. There are many components in high-temperature and high-pressure thermal power plants that are prone to creep, such as main steam pipes, boiler headers, steam piping, high-temperature fasteners, and turbine cylinders. Due to the accumulation of metal creep, metal components may undergo excessive plastic deformation and become unusable, or creep may enter an accelerated phase leading to creep rupture; in either case, the components will fail and be damaged, potentially even causing serious accidents. Therefore, strict creep monitoring is required for high-temperature components that operate over long periods of time. Of course, some plastic deformation of certain components during operation is acceptable

The phenomenon in which metal materials undergo slow plastic deformation under constant temperature and constant stress over a long period of time is known as creep.

The phenomenon in which the strain of a metal material increases over time while the stress remains constant. It is different from plastic deformation, which usually occurs only after the stress exceeds the elastic limit, whereas creep can occur even when the stress is below the force required to reach the elastic limit, as long as the stress is applied for a sufficient length of time. 　　Many materials (such as metals, plastics, rocks, and ice) exhibit creep properties under certain conditions. Due to creep, the stress state of a material at a given instant is generally related not only to the deformation at that instant but also to the deformation processes that have taken place prior to that instant. Many engineering problems involve creep. In materials that maintain a constant deformation, the stress decreases over time; this phenomenon is known as stress relaxation, and it can be considered a form of creep.

The phenomenon in which metal materials undergo slow plastic deformation under the action of constant temperature and constant load over a long period of time.

The phenomenon in which metal materials undergo slow plastic deformation under constant temperature and constant stress over a long period of time is known as creep. For ordinary metals, the phenomenon of creep becomes apparent only under high-temperature conditions. However, certain metals, such as lead, tin, and their alloys, can also exhibit creep behavior at room temperature.

It is the tendency of metal materials to move or deform slowly and permanently under the influence of stress.

The phenomenon in which metal materials undergo slow plastic deformation under constant temperature and constant stress over a long period of time is known as creep.

Creeep refers to the phenomenon in which metal materials undergo slow plastic deformation under the action of constant temperature and constant load over a long period of time. Under high-temperature conditions, the effect of creep on components is very significant. Depending on the method of applying stress, it can be divided into high-temperature compressive creep, high-temperature tensile creep, high-temperature bending creep, and high-temperature torsional creep.