Bolt material and grade introduction

Choose different materials according to the strength grade of the bolt:

CurrentlyQingdao BoltThere are carbon steel, stainless steel, copper and other standard parts on the market.

(1) Carbon steel. We distinguish low-carbon steel, medium-carbon steel, high-carbon steel and alloy steel according to the carbon content of carbon steel materials.

1. Low carbon steel C%60.25%, commonly known as A3 steel in China. There are mainly 1008, 1015, 1018, 1022, etc. abroad. Mainly used for products with no hardness requirements such as grade 4.8 bolts, grade 4 nuts, small screws, etc. (Note: Master driller

1022 kinds of materials are used.

2.Medium carbon steel: 0.25%< c%≤0.45%,="" mainly="" used="" for="" grade="" 8="" nuts,="" grade="" 8.8="" bolts="" and="" grade="" 8.8="" inner="" hexagon="" products="" in="">

3. High carbon steel: C%> 0.45%. Currently not used in the market

4. Alloy steel: Adding alloying elements to ordinary carbon steel, adding some special properties of steel, such as 35, 40 chromium molybdenum, SCM435, 10B38 and other aromatic screws mainly use SCM435 chromium molybdenum alloy steel, the main components are C, Si, Mn , P, S, Cr, Mo.

(2) Stainless steel: performance level: 45, 50, 60, 70, 80

Mainly divided into austenite (18%Cr, 8%Ni) has good heat resistance, corrosion resistance and weldability. A1, A2, A4 martensite, 13% chromium, poor corrosion resistance, high strength and good wear resistance. C1, C2, C4 ferrite stainless steel. Chromium 18% has better upsetting performance and corrosion resistance than martensite. At present, the imported materials in the market are mainly Japanese products. According to the main classification SUS302, SUS304, SUS316.

(3) Copper: Commonly used materials are brass and zinc-copper alloy. H62, H65, and H68 copper are standard parts currently used in the market.

What is the significance of the bolts and nuts of grade 8, 5.8, 8.8, and 10.9? What is the difference with the material?

4.8 grade A3 Q235, Q195 and other low carbon steels, all grade 5.8 materials above Q235 are acceptable without heat treatment

8.8 Thread diameter below 16MM, 35# quenched and tempered heat treatment, 16mm above, 45# and low-carbon alloy steel quenched and tempered, of course medium carbon steel is better, but there are more scraps. Such as 10b21

10.9 grade medium carbon alloy steel 35CRMO 40CR etc.