52100 is a high-carbon chromium bearing steel characterized by high hardness, excellent wear resistance, and good fatigue strength. Its primary application is in the manufacture of bearings (ball bearings and roller bearings). It is also commonly used for cutting tools and cutting edges, as well as gauges, rollers, and other mechanical components that require high hardness and wear resistance. Equivalent grades include China (GB) GCr15, Germany (DIN) 100Cr6 (or 1.3505), and Japan (JIS) SUJ2.

1. Composition of 52100 Bearing Steel¹

2. Properties of 52100 Bearing Steel

This section outlines the key characteristics of AISI/SAE 52100 steel that make it a preferred material in various industries.

Hardness Potential and Heat Treatment Response

One of the standout properties of 52100 bearing steel is its exceptional hardness capability.

• Achievable Hardness: With appropriate heat treatment, 52100 steel consistently achieves a hardness of 60 to 64 HRC throughout its section. For example, a 1-inch-thick piece can reach approximately 60 HRC when tempered around 204°C (400°F).
• Bearing Applications: For critical ball bearing components, a minimum hardness of 62 HRC is typically specified and achieved after hardening and tempering.
• 고온 경도: It’s important to consider that the hot hardness of 52100 steel decreases notably as operating temperatures rise.

2.1 Microstructure Characteristics

The microstructure of 52100 steel after correct heat treatment is fundamental to its performance:

• Typical Structure: It primarily consists of high-carbon martensite with finely dispersed primary (undissolved) spherical carbides. A retained austenite content of 5-10% is also typical.
• Wear Resistance Contribution: For bearing applications, 52100 steel is intentionally austenitized below its Acm temperature. This process encourages the formation of cementite carbide arrays within the final martensitic structure, significantly enhancing wear resistance.
• Cleanliness: A clean microstructure, free from excessive inclusions, is crucial, especially for applications that require highly polished surfaces, such as dies.

2.2 Core Mechanical Strengths of 52100 Steel

52100 alloy steel is engineered for high load-bearing capacity and resilience.

2.3 Fatigue Performance

High fatigue life is a critical property of 52100 bearing steel, particularly for components such as journal bearings subjected to cyclic loading. The fatigue resistance can be influenced by factors such as inclusion content and the precision of heat treatment. Quality control, including fatigue testing, is paramount.

2.4 내마모성

52100 steel demonstrates good wear resistance. This is significantly enhanced by the presence of very small, hard cementite particles that are uniformly distributed within the microstructure after optimal heat treatment. Specialized treatments, like duplex processes, can further improve wear characteristics compared to standard chromizing or other alloy steels like 8620 in certain conditions.

2.5 Hardenability

Thanks to its chromium content, 52100 steel possesses good hardenability. This allows it to achieve consistent hardness through its cross-section in parts up to approximately 1 inch thick. Its hardenability is comparable to that of 5280 steel.

2.6 가공성

For the best machining outcomes and to ensure a uniform response during subsequent hardening processes, a spheroidized microstructure is highly recommended for 52100 steel. This condition improves tool life and surface finish.

2.7 Material Cleanliness and Quality

High-quality 52100 베어링강 is produced with a strong emphasis on internal soundness, cleanliness, and uniform chemical composition.

• Inclusion Control: For critical applications, such as ball bearings, very low levels of non-metallic inclusions (e.g., Types A, B, C, D) and minimal oxygen content are essential.
• Melting Processes: Advanced melting techniques such as consumable-electrode vacuum melting (CEVM) or electroslag remelting (ESR) can provide the exceptionally clean microstructure required for demanding applications like polished dies.
• Casting Considerations: When producing 52100 steel via modern continuous casting, insufficient homogenizing cycles can lead to segregation and undesirable carbide distributions, negatively impacting its properties and heat treatment response.
• Standards: ASTM A 535 covers special quality alloy steel billets, bars, tube rounds, rods, and tubes intended for manufacturing antifriction bearings.

2.8 Dimensional Stability

Achieving very high dimensional stability in 52100 steel components requires precise control over the heat treatment process. It can be sensitive to distortion, and tempering to a lower hardness might be necessary compared to some advanced steels if ultimate stability is the primary goal. Incorrect austenitizing temperatures or tempering practices can lead to cracking.

2.9 Weldability

It is important to note that 52100 bearing steel is generally considered nonweldable due to its high carbon content, which makes it prone to cracking during and after welding.

2.10 Toughness

When correctly oil quenched from around 850°C (1560°F) to achieve a microstructure of dispersed spherical carbides in tempered martensite, 52100 steel exhibits good toughness. This can be assessed using standard tests like Charpy V-notch impact energy and plane-strain fracture toughness (KIc). Studies have shown that 52100 bainite can offer higher impact toughness compared to some powder-forged steels.

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3. Heat Treatment

52100 steel is a prominent bearing steel, valued for achieving high hardness. This hardness is primarily developed through the formation of martensite in its microstructure, a result of precise heat treatment of 52100 steel. Understanding these thermal processes is key to optimizing your 52100 steel components.

3.1 Austenitizing

The austenitizing stage involves heating the 52100 steel to transform its structure. For optimal results, the austenitizing temperature for 52100 steel should be meticulously controlled, ideally around 855 +/- 5°C. Using temperatures such as 840°C or 850°C before quenching is also noted. It is important to avoid heating 52100 steel above this specific range (overheating), as this can lead to excessive retained austenite and an increased risk of cracking upon quenching.

3.2 Quenching

Following austenitizing, 52100 steel is rapidly cooled (quenched). Common quenching media for 52100 steel include Oil and Salt Bath.

Martempering is another technique used for 52100 steel. This typically involves quenching in a hot salt bath, followed by cooling in still air, a method chosen to minimize distortion.

3.3 Tempering

After the hardening process, tempering is a crucial step in the heat treatment cycle of 52100 steel. Tempering is performed at temperatures below the steel’s Ac1 (lower critical) point. Its primary purpose is to enhance toughness and relieve internal stresses within the 52100 steel.

Tempering Temperatures and Resulting Hardness

The choice of tempering temperature directly influences the final properties of 52100 steel.

A double temper is often employed for 52100 강철, sometimes with an intermediate subzero (cryogenic) treatment. This helps ensure that any retained austenite is transformed and that stresses are effectively relieved.

3.4 Annealing 52100 Steel

When 52100 강철 needs to be softened, for instance, before machining, annealing is the appropriate 52100 steel heat treatment.

Annealing Processes and Outcomes for 52100 Steel

Spheroidizing, achieved through controlled cooling rates during annealing, produces globular carbides in a ferrite matrix, which significantly enhances the machinability of 52100 강철.

4. Surface Treatment of 52100 Steel

To significantly enhance the performance of 52100 steel components, particularly their surface hardness and wear resistance, various advanced surface treatment technologies can be employed.

Chromizing is a commonly used surface treatment method. For superior wear resistance, a composite process known as Duplex Treatment can be employed. This process ingeniously combines ‘chromizing’ with Plasma Nitriding, delivering wear resistance far exceeding that of chromizing alone.

5. 응용 프로그램

Primarily, 52100 steel is used for manufacturing ball bearings and is a classic grade for rolling bearing steel. Its critical role in high-performance bearing components is further highlighted by its specification in ASTM A295 (for hot-rolled alloy steel bars for anti-friction bearings) and ASTM A535 (for special quality ball and roller bearing steel).

After heat treatment, 52100 steel is well-suited for applications demanding High load-bearing capacity, Excellent wear resistance, and Long fatigue life.

Consequently, it is successfully applied in electric motors, gearboxes, gas turbine aeroengine main shafts, helicopter transmissions, and steel rolling mill support bearings. These varied 52100 steel applications demonstrate its versatility.

Beyond bearings, its uses extend to specialized manufacturing processes. For instance, it is employed as a cladding material in plasma transferred arc (PTA) powder deposition welding. A 52100 steel layer cladding a substrate, such as AISI 1022M, provides significant resistance to wear and fatigue, with the critical area for fatigue life designed within this cladding.

Furthermore, its properties make 52100 steel valuable for certain tool steel applications. Categorized as a semi-high-speed steel, it can achieve hardness in the 62–64 HRC range. While its tempering and wear resistance may be lower than some true high-speed steels, it is used for some cold work tools or mechanical components. For dies up to 50 mm (2 inches) in diameter, consumable-electrode vacuum-melted or electroslag remelted 52100 steel is utilized. Heat-treated to 59-61 HRC, this material provides optimum die life and is suitable for photochemical etching to create polished, low-relief die surfaces.

6. AISI 52100 Equivalent Standards

• AISI/SAE: 52100
• China(GB): GCr15
• UNS: G52986
• DIN (W-Nr): 3505 (also known as 100Cr6)
• JIS: SUJ2

6. 공급 형태 및 치수

The 52100 bearing steel we supply is available in various forms, including round bars, sheet plates, slabs, flat bars, square bars, and blocks. The dimensions of the flat bar range from: width 20–600 mm × thickness 20–400 mm × length 1,000–5,500 mm. The dimensions of the round bar range from a diameter of 20–400 mm × a length of 1,000–5,500 mm. The block dimensions are obtained by cutting the flat bar.

UT 테스트: 1921-84년 9월 D/d, E/e. 

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Delivery time: 30-45 days. 

1. ASM International. (1990). ASM handbook: Vol. 1. Properties and selection: Irons, steels, and high-performance alloys. ASM 인터내셔널. ↩︎

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