DIN 931 Galvanized Carbon Steel Hex Bolts Half-Thread White Blue Color

About the Products:

    Although the hexagonal half thread bolts are not as frequently used as the hexagonal full thread bolts, they are also widely used in the production, installation and maintenance of various machinery and equipment, electronic products, communication equipment, furniture equipment, construction industry and other industries.

    Half-Thread Hexagon socket bolts are divided into three different grades, A, B and C. Grade A and B hexagon bolts are mostly used in machinery and equipment with smooth, bright surfaces and high precision requirements. The coarse threaded hexagon bolts are commonly used, the fine threaded ones are usually marked or have special instructions, the fine threaded hexagon bolts have better self-locking performance.

Products Details:

Drawings about DIN 931-1 - 1987 Standard

Drawings about DIN 931-2 - 2009-B CALSS Standard

Additional Information:

    The definition of carbon steel is any steel with a carbon content of up to 2.1% of its weight. As the carbon content increases, carbon steel bolts tend to become harder. Although the hardness increases after heat treatment, the ductility of the steel decreases after heat treatment. Regardless of the heat treatment applied to carbon steel alloys, the higher carbon content of the material reduces the weldability of mild steel fasteners and also effectively lowers the bolt's melting point, so most carbon steel bolts are usually relatively weak. As a result they also exhibit low hardness. However, mild steel is highly flexible. High ductility is a property that makes the material well suited for machining and welding. The lack of different elements - used as alloying agents rather than other classes of steel - is the reason why nuts and bolts are called low-cost bolts. Carbon steel nuts and bolts grades are divided into three different categories based on the content of low carbon, medium carbon and high carbon steels.

Introduction About low, medium and high Carbon Steel:

    Low carbon steel hexagonal bolts are the most widely used category of all carbon steel groups. Low carbon steel threaded bolts have alloys that typically have a carbon content of less than 0.25% of their total weight. Since this type of carbon steel bolt cannot be hardened by heat treatment to promote martensite formation, the alloy is cold worked.

    In this particular category of low carbon steel is another type of steel called High Strength Low Alloy Steel, or HSLA for short. although HSLA bolts belong to a class of low carbon steel, it can be noted that the alloy of HSLA bolts contains other elements such as copper, nickel, vanadium and molybdenum. The combination of said elements adds up to 10% of the weight of the steel content. As the name implies, HSLA bolts have a higher strength, achieved by heat treatment. These washers remain ductile, making them easy to form and machine, while offering higher corrosion resistance than ordinary mild steel.

Medium carbon steel bolts, anchor bolts, threaded rods, studs, nuts and self-drilling screws have a carbon content between 0.25 - 0.60% and a manganese content between 0.60 - 1.65% of their weight. The mechanical properties of these bolts are improved by heat treatment. The heat treatment process involves austenitizing, followed by quenching and tempering. Undergoing these processes is what gives it its martensitic microstructure. Hardened medium carbon steel bolts have greater strength compared to low carbon steel. However, this is a property that comes at the expense of toughness and flexibility.

    The carbon content of high carbon steel bolts ranges from 0.60 - 1.25%. High-carbon steel has a manganese alloy content in the range of 0.30 - 0.90 percent. Of all three grades, high-carbon steel threaded rod has the highest hardness and toughness, while exhibiting the lowest ductility. The high wear resistance is demonstrated by the fact that these screws are almost always hardened and tempered.

    The two subcategories of tool and die steels, high-carbon steels, contain additional alloying elements such as chromium, molybdenum, vanadium and tungsten. The addition of these minerals results in very hard, strong and wear-resistant hexagonal bolts due to the formation of carbide compounds; for example, tungsten carbide (WC).

Introduction About Grade A, B and C:

    Hexagonal bolts are divided into three grades: Grade A, Grade B and Grade C. Bolt connection is divided into two categories: ordinary bolt connection and high strength bolt connection. Ordinary bolts have A, B, C grade. Here A, B, C grade refers to the tolerance grade of the bolt, A grade is the precision grade, B grade is the general grade, and C grade is the looser grade.

    Grade A and B are refined bolts and grade C is rough bolts. The difference between A and B grade refined bolts is only the length of the bolt rod, and C grade bolts are generally used in the connection of tension along the bolt rod axis, as well as the secondary structure of the shear connection or temporary fixing during installation.

    Grade A is used for important, high precision assembly and subject to large shock, vibration or variable load. grade A is used for bolts with d=1.6-24mm and l≤10d or l≤150mm. grade B is used for bolts with d>24mm or l>10d or l≥150mm, thin rod grade B is M3-M20 hexagonal flange face bolts with better anti-loosening performance. grade C is between M5-M64. Grade C hexagonal bolts are mainly used in the appearance of rougher, not high precision requirements of steel construction machinery, equipment, commonly used connection is generally selected C level of accuracy.