【Mechanical Equipment Technology Exchange Edition】Mechanical Equipment 【Daily Question】20190718
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Question: What are the factors that affect the thermal fatigue of metal materials? There are no answers provided for this series of posts; fellow netizens are free to share their own opinions – just reply with what you understand. Replies earn rewards ranging from 5 to 15 points; all forum members are welcome to participate actively and support the development of the forum! ! ! Chemical Equipment and Machinery
①Thermal conductivity of steel. Steel has high thermal conductivity, which reduces the degree of heating of the metal on the surface of the mold, thereby decreasing its tendency to suffer from thermal fatigue. ’②Effect of the steel’s critical point. Generally, the higher the critical point (Acl) of steel, the lower its tendency to thermal fatigue
The fatigue strength of materials is highly sensitive to various external and internal factors. External factors include the shape and size of the parts, surface finish, and operating conditions, while internal factors include the composition of the material itself, its microstructural state, purity, and residual stresses. Even slight changes in these factors can cause fluctuations or even significant changes in the fatigue performance of the material. Such as: the influence of stress concentration, the influence of dimensional factors, the influence of surface finish, the influence of loading history, the influence of chemical composition, the influence of heat treatment and microstructure, the influence of inclusions, changes in surface properties, and the influence of residual stresses, etc
(1) The greater the temperature gradient and frequency of changes in the environment, the more likely heat fatigue will occur. (2) When materials with different coefficients of thermal expansion are combined, thermal fatigue is likely to occur. (3) The grains are coarse and uneven, making heat fatigue likely to occur. (4) The second-phase particles distributed at the grain boundaries contribute to the occurrence of thermal fatigue. (5) The material has poor plasticity and is prone to thermal fatigue. (6) The geometric structure of the parts exerts a strong constraint on the expansion and contraction of the metal, making thermal fatigue likely to occur.
(1) The greater the temperature gradient and frequency of changes in the environment, the more likely heat fatigue will occur. (2) When materials with different coefficients of thermal expansion are combined, thermal fatigue is likely to occur. (3) The grains are coarse and uneven, making heat fatigue likely to occur. (4) The second-phase particles distributed at the grain boundaries contribute to the occurrence of thermal fatigue. (5) The material has poor plasticity and is prone to thermal fatigue. (6) The geometric structure of the parts exerts a strong constraint on the expansion and contraction of the metal, making thermal fatigue likely to occur.
(1) The greater the temperature gradient and frequency of changes in the environment, the more likely heat fatigue will occur. (2) When materials with different coefficients of thermal expansion are combined, thermal fatigue is likely to occur. (3) The grains are coarse and uneven, making heat fatigue likely to occur. (4) The second-phase particles distributed at the grain boundaries contribute to the occurrence of thermal fatigue. (5) The material has poor plasticity and is prone to thermal fatigue. (6) The geometric structure of the parts exerts a strong constraint on the expansion and contraction of the metal, making thermal fatigue likely to occur.
(1) Temperature gradient and variation frequency； (2) Combinations of materials with different coefficients of thermal expansion ； (3) The grains are coarse and uneven ； (4) Second-phase particles distributed at grain boundaries ； (5) Plasticity of the material ； (6) The restraining effect of the geometric structure of the part on the expansion and contraction of the metal.
The eight factors affecting the fatigue strength of metal materials: The fatigue strength of materials is highly sensitive to various external and internal factors. External factors include the shape and size of the parts, surface finish, and operating conditions, while internal factors include the composition of the material itself, its microstructural state, purity, and residual stresses. Even slight changes in these factors can cause fluctuations or even significant changes in the fatigue performance of the material. The main factors are: the effect of stress concentration, the effect of size factors, the effect of surface finish, the effect of loading history, the effect of chemical composition, the effect of heat treatment and microstructure, the effect of inclusions, as well as changes in surface properties and residual stresses
Impurities, heat treatment, temperature, second-phase structure, matrix structure, etc
(1) The greater the temperature gradient and frequency of changes in the environment, the more likely heat fatigue will occur. (2) When materials with different coefficients of thermal expansion are combined, thermal fatigue is likely to occur. (3) The grains are coarse and uneven, making heat fatigue likely to occur. (4) The second-phase particles distributed at the grain boundaries contribute to the occurrence of thermal fatigue. (5) The material has poor plasticity and is prone to thermal fatigue. (6) The geometric structure of the parts exerts a strong constraint on the expansion and contraction of the metal, making thermal fatigue likely to occur.
The main factors include: temperature, microstructure, impurities, heat treatment processes, material defects, etc.