Many users are not clear about the difference between high-strength nuts and general nuts. In fact, they can be easily distinguished by understanding their standard and other characteristics. The so-called high-strength nut is a special bolt with high strength and high fatigue resistance used in special equipment or engineering. Of course, generally high-strength nuts are used with high-strength bolts to achieve better application.
We generally see that many bolts with M heads in the market are general nuts, not high-strength nuts. The calibration side of the general hexagonal head nut is the following pattern M30, and M30 indicates the thread standard, that is, the thread inner diameter is 30mm. Grade 10 indicates the functional grade of the bolt, and tZn is the surface treatment method.
Other types of bolts also have their own expressions, but generally threaded bolts must be "M" as the original bolt function level:
The functional level of the nut is divided into 3, 4, 4, 5, 5.8, 6, 8, 10, 12 so many levels from small to large. This symbolic method means taking 10 as an example 10 to indicate 1/100 of the tensile strength of the bolt, which means that the tensile strength of this grade of bolt must reach the level of 1000 MPa, which may be higher than 1000 MPa in practice.
GB/T3098.1 rules the smaller tensile strength of this grade of bolts must be greater than 1040MPa. After the decimal point, the yield strength ratio is indicated, that is, the bolt's (yield strength/tensile strength)=0.9, that is, the yield strength=1000*0.9=900MPa, and the yield strength of this grade of bolt must be higher than 900MPa to be qualified.
Generally, we call the nuts of the three grades of 8.8, 10.9, and 12.9 as high-strength nuts.
It should be noted that GB/T3098.1 does not give detailed values ​​of yield strength for these three grades of bolts. This is because for high-strength bolts 0.8 and 0.9 are the smaller yields regulated by this grade. Strength ratio. Because high-strength bolts are used for very important links, there is no spot on the market. It is necessary to make an order with the bolt manufacturer. Therefore, the detailed yield ratio is usually produced by the buyer with a detailed value.