45# Carbon Steel Seamless Round Pipe For Connecting rod, bolt, gear and shaft under alternating load

45# seamless steel tube after tempering parts have good comprehensive mechanical properties, widely used in a variety of important structural parts, especially those working under alternating load connecting rod, bolt, gear and shaft, etc.. But the surface hardness is low, not wear-resistant. The surface hardness of parts can be improved by quenching and tempering.

45# is GB,JIS called :S45C,ASTM called 1045,080M46,DIN called :C45.

Its chemical composition of carbon (C) content is 0.42~0.50%, Si content is 0.17~0.37%, Mn content is 0.50~0.80%, Cr content <=0.25%

Recommended heat treatment temperatures: normalizing 850, quenching 840, tempering 600.

No. 45 steel is high quality carbon structure steel, hardness is not high, easy cutting, mold is often used as template, pin, guide column, but must be heat treatment.

1. No. 45 steel is qualified for hardness greater than HRC55 (up to HRC62) before tempering after quenching.

The maximum practical hardness is HRC55 (high-frequency hardening HRC58).

2. No. 45 steel should 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 various important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads. But the surface hardness is low, not wear-resistant. The surface hardness of parts can be improved by quenching and tempering.

Carburizing treatment is generally used for surface wear-resistant, impact-resistant core heavy-duty parts, and its wear resistance is higher than quenching and tempering + surface quenching. Its surface carbon content is 0.8-1.2%, the core is generally 0.1-0.25% (under special circumstances, 0.35%). After heat treatment, the surface can obtain 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 advantage of carburizing treatment will be lost. The use of carburizing process of materials, carbon content is not high, to 0.30% core strength can be very high, rarely seen on the application. Never seen examples, only introduced in textbooks. The process of quenching and tempering + high frequency surface hardening can be adopted, and the wear resistance is slightly worse than carburizing.

According to the GB/T699-1999 standard, the recommended heat treatment system of 45 steel is 850℃ normalizing, 840℃ quenching and 600℃ tempering. The yield strength of 45 steel is greater than or equal to 355MPa.

GB/T699-1999 standard 45 steel tensile strength is 600MPa, yield strength is 355MPa, elongation is 16%, area reduction is 40%, impact energy is 39J.

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