What is the hardness of 45# steel without any treatment? What is the hardness after tempering? What is the hardness after quenching
How to change lowe's hardness and cloth's hardness
No.45 steel is called S45C in JIS, 1045,080M46 in ASTM, and C45 in DIN
No. 45 steel is high quality carbon structure steel, hardness is not high free cutting processing, mould is often used as template, pin, guide column, etc., but must be heat treatment.
45 # steel is widely used in the manufacture of machinery and has good mechanical properties. However, this is a medium carbon steel, the quenching performance is not good, no. 45 steel can be hardened to HRC42~46. Therefore, if surface hardness is needed and the superior mechanical properties of 45 # steel are desired, the surface of 45 # steel is often carburized and quenched, so that the required surface hardness can be obtained.
[1]45 steel is qualified if its hardness is greater than HRC55 (up to HRC62) before tempering after quenching.
The maximum hardness in practice is HRC55 (high frequency quenching HRC58).
[2]45 steel shall not adopt the heat treatment process of carburizing and quenching.
After quenching and tempering, the parts have good comprehensive mechanical properties and are widely used in all kinds of important structural parts, especially the connecting rod, bolt, gear and shaft which work under alternating load. But the surface hardness is low, not wear - resistant. The surface hardness of the parts can be improved by quenching and tempering.
Net belt type quenching furnace, roller net belt furnace carburizing treatment is generally used for surface wear resistance, core impact resistance of heavy duty parts, its wear resistance is higher than quench + surface. The surface carbon content is 0.8-- 1.2%, and the core part is generally 0.1-- 0.25% (0.35% in special cases). After heat treatment, the surface can obtain a high hardness (HRC58-62), the core hardness is low, impact resistance.
If 45 steel is carburized, hard and brittle martensite will appear in the core after quenching, and the advantages of carburizing treatment will be lost. At present, materials using carburizing process are not high in carbon content, and the core strength of 0.30% has reached a high level, which is rarely seen in application. 0.35% has never seen an example, which is only introduced in textbooks. Can be used to quench + high frequency surface process, wear resistance is slightly worse than carburizing.
The recommended heat treatment system for 45 steel specified in GB/T699-1999 standard is 850℃ normalization, 840℃ hardening, 600℃ tempering, and the performance achieved is yield strength ≥355MPa
According to GB/T699-1999 standard, 45 steel has tensile strength of 600MPa, yield strength of 355MPa, elongation of 16%, reduction of section of 40% and impact work of 39J
The hardness of no. 45 steel is less than HRC28, so it is soft and does not wear well. After quenching, the hardness (note that it can be) can be greater than HRC55, with good wear resistance.
After quenching, the hardness of no.45 steel can be greater than HRC55. However, it is of small cross section, and the hardness will be reduced if the cross section is larger. And winter cracking may also occur. Pay attention to all these aspects.
Do not use the surface nitriding treatment, although the surface hardness can be improved a lot, but the matrix material hardness will be very low. Although it is wear - resistant, it will press out a small pit.
On 2018-08-08 11:45:46
