What are the common materials for fasteners?
What are the common materials for fasteners?
Currently, fasteners on the market mainly include four raw materials: stainless steel, carbon steel, copper, and aluminum alloy.
1. Carbon steel. Low carbon steel, medium carbon steel, high carbon steel and alloy steel are distinguished by the carbon content in the carbon steel material.
(1) Low carbon steel C% ≤ 0.25% is generally called A3 steel in China. Overseas, they are basically called 1008, 1015, 1018, 1022, etc. Mainly used in products without strength standards such as grade 4.8 screws, grade 4 nuts, and small screws. (Note: Drill tail screws are generally made of 1022 raw material.)
(2) Medium carbon steel 0.25% 0.60%. There is basically no application of this material on the market at present.
(3) Alloy steel: Add alloy components to ordinary carbon steel to add some special features to construction steel: such as 35, 40 chromium molybdenum, SCM435, 10B38. Grade 12.9 screws use SCM435 chromium molybdenum alloy steel, and the key components are C and Si , Mn, P, S, Cr, Mo.
2. Stainless steel. Property levels: 45, 50, 60, 70, 80 are mainly divided into martensite (18% Cr, 8% Ni) with good temperature resistance and good corrosion resistance. A1, A2, and A4 martensite (13% Cr) have weak corrosion resistance, high strength, and good wear resistance. C1, C2, C4430 stainless steel. 18% Cr is better for upsetting and has better corrosion resistance than austenite. The raw materials currently on the market are mainly divided into SUS302, SUS304 and SUS316 according to their grades.
3. Copper. Common materials are brass and copper alloy. In the market, H62, H65, and H68 copper are generally used as standard products.
4. Aluminum alloy has low density, but very high compressive strength, which is close to or even exceeds that of heat-resistant cast iron. It has good plasticity and can be made into various aluminum profiles. It has good electrical conductivity, heat transfer and corrosion resistance. Industrially It is widely used and its usage is second only to steel.
5. Alloy steel also refers to chromium-molybdenum alloy steel, such as SCM435, etc.
Common raw materials for fasteners
(I) Carbon steel, alloy steel, special steel
1. Bolts, screws, and screws of grades 3.6, 4.6, 4.8, 5.6, 5.8, and 6.8 generally use carbon steel, and no heat treatment process is required; grades 8.8 and 9.8 generally use low-carbon environmentally friendly alloy steel or medium carbon steel, quenched and tempered; grades 10.9 generally use low- and medium-carbon alloy steel or alloy steel, quenched and tempered; grades 12.9 generally use alloy steel, quenched and tempered.
2. Nuts Grades 4, 5, and 6 generally use carbon steel, and can also be made of free-cut steel, without the need for heat treatment process; grades 8 and 9 generally use medium carbon steel, quenched and tempered; grades 10 and 12 are to improve physical properties. If necessary, alloy components can be added, quenched and tempered.
3. Set screws 14H are generally made of carbon steel, and no heat treatment process is required; 22H and 33H are generally made of carbon steel, quenched and tempered; 45H is generally made of alloy steel, quenched and tempered.
4. Flat washers HV140 are generally made of low carbon steel; HV300 are generally made of medium carbon steel, and heat treatment process is required.
5. Self-tapping screws/drill nails are generally made of medium carbon steel such as SWRCH22A, and the surface must be carburized.
6. Toothed and serrated locking washers, I-shaped and wave-shaped elastic washers are generally made of 65Mn
7. Elastic washers are generally made of tool steel 70/ 65Mn/60Si2Mn, quenched and tempered.
8. Pins can generally be made of carbon steel 35#, quenched and tempered HRC28-38, 45#, quenched and tempered HRC38-46; alloy steel 30CrMnSiA, quenched and tempered HRC35-41; special steel 1Cr13/2Cr13, Cr17.i2, 1Cr18.I9Ti
(II) Stainless steel raw materials
Stainless steel material: The material of stainless steel bolts is composed of Q215 and Q235, as well as 25 and 45 steel materials. The threads between the bolts sometimes need important connecting parts. At this time, 15Cr and 20Cr and 30CrMri steel alloys can be selected to improve the mechanical properties of the bolts. It contains 9 chemical components, namely Ni, Cu, C, S, Si, P, Mn, and Cr. Stainless steel materials:
201, 304, 316, 304L, 316L, 2205, 2507, 310S, 321, 904L, 667, etc.
Introduction to types: 302HQ is mainly used for tapping; SUS304, A2 is another name for it, the main production material for stainless steel bolts, stainless steel screws, stainless steel washers and stainless steel nuts, with a slightly higher strength grade; SUS316 and SUS316L, that is, A4, are more corrosive than A2, and the production of stainless steel bolts, stainless steel screws, stainless steel washers and stainless steel nuts can have the same strength grade as A2 or be stronger than A2.
