In daily use, high-strength nuts are generally used in special areas, and ordinary nuts are used on weekdays, so how should we distinguish what is a high-strength nut? The so-called high-strength nuts are specially made bolts with high toughness and high fatigue resistance that are commonly used in special equipment and projects. Of course, generally high-strength nuts are used with high-strength bolts to achieve a better user experience. We generally see that many bolts with the word M in the market are ordinary nuts, not high-strength nuts. The calibration of ordinary hexagonal head nuts, such as M30, where M30 indicates the thread standard, is actually the inner diameter of the thread. 30mm, grade 10 indicates the application performance level of the bolt, and tZn is the surface treatment method. Other types of bolts also have their own expressions, but generally those with external threads must be expressed as"m"Start bolt performance level: The nut performance level is divided into 3, 4, 4, 5, 5.8, 6, 8, 10, 12 levels from small to large. This type of marking means that taking 10 as an example, 10 marks 1/100 of the tensile strength of the bolt, that is to say, the tensile strength of this level of bolt must reach the level of 1000MPa, and it may actually be higher than 1000MPa. GB/T3098.1 requires the minimum tensile strength of bolts of this level to exceed 1040MPa. The yield strength ratio marked after the decimal point is actually the bolt’s (yield strength/tensile strength)=0.9, that is, the yield strength=1000*0.9=900MPa. The yield strength of bolts of this level needs to be higher than 900MPa to be regarded as meeting the standard. Generally, we call nuts of 8.8, 10.9, and 12.9 grades high-strength nuts. It should be noted that I cannot get the specific value of the yield strength here, mainly because 0.8 and 0.9 are the small yield ratios specified in this grade for high-tenacity bolts, because high-tenacity bolts are used for critical connections, and there are no spot transactions on the market at present, and they must be ordered from high-strength nut manufacturers. Therefore, the specific yield ratio is usually manufactured by the buyer specifying the specific value.