Nuts And Bolts Material

DT Fastener provides fasteners mainly made by carbon steel, supplemented by stainless steel. We handle everything from low carbon steel to alloy materials and everything in between. We can either supply it off our stock or we can make it if it is not available.

Common Fastener Material from DT 

1. Fastener Materials For External Threads Such As Bolts

a. For some low-strength carbon steel fasteners with no mechanical performance requirements or ISO Class 4.8, SAE Grade, 1-2., Q235A SAE 1015 DIN C15 is sufficient, no heat treatment is required at all, and it is directly cold-worked, while the grade is slightly lower. Higher fasteners such as ISO Class 6.8 SAE Grade 3-4 should use steel with a carbon content of more than 0.2%, such as C1020 C1022 M120 ML35, etc. Such screws do not need any heat treatment, and the cold working strength is completely acceptable fulfil requirements. In fact, the higher the carbon content, the more difficult the cold forming will be.

b. The most commonly used screws are ISO Class 8.8 SAE Grade 5 screws, generally using "medium carbon steel, ML35 SAE 1035 DIN 35 JIS SWRCH35K after heat treatment (quenching and tempering), SAE5140 40Cr, etc. can also be used. The increase of alloy elements is of great help to the hardenability of heat treatment, so alloy nut bolt raw material can be used for large-sized screws, so that the use of medium carbon steel will not cause the central part that we often say "hardenable". The existence of the phenomenon of penetration.

c. ISO Class 9.8, 10.9 SAE Grade 8 should use low to medium alloy nut bolt material, after heat treatment (quenching + tempering), the alloy material has a good combination of material mechanical properties. Commonly used raw materials for this nut bolt manufacturing are 40Cr, 35CrMo, SAE5140, SCM435, SAE4135, SAE4137, JIS SCr440(H), DIN 41Cr4, etc. In fact, 45# can also meet the required mechanical properties, but it is slightly better than alloy steel in terms of comprehensive mechanical properties. inferior.

d. ISO Class12.9 ASTM A574 is a high-strength bolt with high requirements for mechanical properties. It should be heat treated (quenched + tempered) with medium carbon alloy steel, such as SCM435, 35CrMo, SAE 4137, SAE4135, DIN 34CrMo4, If the surface treatment of such high-strength bolts is subject to the process of pickling, hydrogen embrittlement will occur, so there must be a process of dehydrogenation.

2. Fastener Materials For Internal Threads Such As Nuts

a. For those with no mechanical property requirements or ISO Class 5-6, SAE Grade 3-4 generally use C1010 Q235A or C15, no heat treatment, cold working. ISO Class 8, SAE Grade 5, generally use M135, SAE1035, DIN C35, small size nuts can achieve the required mechanical properties without heat, large sizes need to undergo heat treatment (quenching + tempering).

b. ISO Class 10, SAE Grade 8 generally uses medium carbon steel to meet its strength requirements after heat treatment. Such as medium carbon steel such as SAE1035. One thing everyone must pay attention to is that nuts and bolts are different, and their force is mainly compression rather than an extension. Therefore, the strength of the nut is not only related to the material but also related to many factors, including accuracy, pitch, nut inner chamfer and nut thickness, etc.