Nondestructive flaw detection
2016-11-11 Rongda test 261 times
Detection Purpose: Detection of grain size of metal materials
Detection range: Metal, alloy, ceramic and other solid with crystal structure
The smaller the grain size is, the larger the grain size is. Generally, the relationship between the grain size and the yield strength of the material is in accordance with the shell pitch relationship in the steady state, that is, the smaller the grain size, the greater the strength and hardness. In addition, the grain size also affects the corrosion resistance of metal materials. According to the austenitizing condition and growth tendency, the grain size of steel can be divided into three kinds: initial grain size, actual grain size and intrinsic grain size. Initial grain size The initial grain size refers to the grain size of the initial austenite grain formed in the process of austenitizing when the steel is heated above the critical temperature, that is, the austenite transformation is just completed, and the grain size when the grain boundary begins to contact is called the initial grain size. Actual grain size The actual grain size refers to the actual grain size obtained under a certain actual condition. Intrinsic grain size The intrinsic grain size only represents the growth tendency of austenite under a certain condition. Usually, the standard experimental method is adopted, that is, the steel is heated to (930 + - 10) Celsius, and the austenite grain size is measured after 3-5 hours of heat preservation.
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