What Are Shortcomings of Carbon Steel As the Material of Fasteners?

1. Hardenability is low. For the fastener parts that of the diameter of greater than 20 ~ 25mm, water cooling can not be hardened, as a result, the part sections after air-hardening are not uniform. In addition, the rapid quenching can cause deformation or cracking of fasteners, like the countersunk head knurled body rivet nut.

2. Strength and hardness is low, resulting in bulky components, furthermore, the inefficient use of strength is a shortcoming as well. Such as the carbon steel σs / σb = 0.5-0.6, alloy steel is 0.8-0.9.

3. Tempering stability is poor, which is an obstacle to get excellent comprehensive mechanical properties.

4. It is a relatively fragile material that can not meet some special performance requirements, such as heat resistance, wear resistance and corrosion resistance.

The only effective solution of getting rid of those disadvantages is to make the alloy. Alloying elements are added to improve the mechanical properties of steel and make steel fasteners-steel rivet nuts to obtain some special physical and chemical properties.