Characteristics and applications of high carbon steel pipes

High carbon steel is often called tool steel, with a carbon content ranging from 0.60% to 1.50%, which can be quenched and tempered. Hammers, crowbars, etc. are made of steel with a carbon content of 0.75%; cutting tools such as drills, taps, reamers, etc. are made of steel with a carbon content of 0.90% to 1.00%.

Performance characteristics of high carbon steel pipes:

Advantages:

1. After heat treatment, high hardness (HRC60-65) and good wear resistance can be obtained.
2. The hardness is moderate in the annealing state and has good machinability.

3. Raw materials are easy to obtain and the production cost is low.

The disadvantages are:

1. Poor hot hardness. When the working temperature of the tool is greater than 200°C, its hardness and wear resistance drop sharply.
2. Low hardenability. The diameter of complete hardening during water quenching is generally only 15-18mm; the maximum diameter or thickness of complete hardening during oil quenching is only about 6mm, and it is easy to deform and crack.

Application fields of high carbon steel pipes:

‌High carbon steel pipes are mainly used in the following fields:

‌1. Mechanical manufacturing ‌
High carbon steel pipes are widely used in mechanical manufacturing. Many mechanical equipment and parts require the use of high carbon steel pipes to ensure the overall rigidity and strength of the equipment.

Applicable scenarios: hydraulic props, heavy machinery transmission shafts and other parts that require high compressive strength.

Hydraulic cylinder/oil cylinder: used in the hydraulic system of heavy machinery (such as excavators and injection molding machines), using the high compressive strength of high carbon steel (up to 800MPa or more) to withstand frequent high-pressure shocks.
Drive shaft, connecting rod: high hardness (HRC 50~60) is suitable for low-speed and high-torque transmission parts, but surface quenching treatment is required to improve fatigue life.
Mold guide sleeve: such as the guide sleeve of the cold stamping mold, the wear resistance is better than ordinary carbon steel.

2. Mining industry
Wear-resistant equipment and mining machinery: slurry conveying pipelines (lifespan is 3 to 5 times longer than ordinary steel pipes), crusher liners, ball mill accessories (high hardness and wear resistance).

3. Automobile industry
Suspension parts:
High-stress suspension arms of some commercial vehicles (need to be tempered to improve toughness).

Clutch shaft:
High-rigidity seamless pipes are used for high-torque transmission, but welding should be avoided (flange connection should be used instead).

‌4. Construction industry‌
High carbon steel pipes are also used for structural supports, brackets and other parts of the construction industry, using their high strength and plasticity to meet the needs of various complex shapes and loads. ‌

5. Military and aerospace‌
In the military and aerospace fields, high carbon steel pipes are used to manufacture weapons, ammunition and certain parts of aerospace vehicles, using their high strength and good processability‌.

6. Oil and gas industry‌

In the field of oil and gas transportation, high carbon steel pipes have become an ideal choice for transporting oil and natural gas due to their good mechanical properties and pressure resistance. ‌

7. Special industries
Drill rods, saw blade backing (high torsional strength).
Agricultural machinery tools: such as harvester blades, saw blade backing, and caliper sleeves, rely on the dimensional stability of high carbon steel.

Bearing ring blanks:

GCr15 and other high carbon chromium steel seamless pipes are forged to make bearing rings.

The hardness and strength of high carbon steel mainly depend on the amount of solid dissolved carbon in the steel, and increase with the increase of solid dissolved carbon. When the solid dissolved carbon content exceeds 0.6%, the hardness will no longer increase after quenching, but the number of excess carbides will increase, the wear resistance of the steel will increase slightly, and the plasticity, toughness and elasticity will decrease. For this reason, different steel grades are often selected according to the use conditions and the matching of the strength and toughness of the steel. For example, to manufacture springs or spring-type parts with little force, 65 steel with a lower carbon content can be selected. Generally, high carbon steel can be produced by electric furnaces, open furnaces, and oxygen converters. When higher quality or special quality is required, electric furnace smelting plus vacuum consumable or electroslag remelting can be used. During smelting, the chemical composition, especially the content of sulfur and phosphorus, is strictly controlled. In order to reduce segregation and improve isotropic properties, the steel ingot can be subjected to high-temperature diffusion annealing (especially important for tool steel). During hot processing, the stop forging (rolling) temperature of hypereutectoid steel is required to be low (about 800℃). After forging and rolling, the precipitation of coarse network carbides should be avoided. Attention should be paid to slow cooling below 700℃ to prevent cracks caused by thermal stress. Surface decarburization should be prevented during heat treatment or hot processing (especially important for spring steel). There should be a sufficient compression ratio during hot processing to ensure the quality and performance of the steel.

Conclusion:
The core advantages of high carbon steel pipes are high strength, high wear resistance, seamless safety, and are suitable for hydraulic machinery, mining equipment, precision tools and other fields. However, its low toughness and difficult welding characteristics limit its application in corrosive, low temperature or impact environments. Reasonable material selection + appropriate heat treatment can maximize its performance advantages.

Read more: Carbon steel tube material and use or Characteristics and application of low carbon steel pipe