what is 65mn steel？
65Mn steel is a common spring steel specified by Chinese standards, primarily developed for the knife manufacturing industry. This steel exhibits several advantageous properties, including high wear resistance, the ability to achieve a lamellar microstructure after heat treatment, ease of sharpening, and a reasonable level of elasticity. Comprising mainly high carbon and manganese, 65Mn falls into the category of medium-high carbon steel, with a carbon content of approximately 0.65% and manganese content between 1.1% and 1.2%. Compared to low carbon steels, 65Mn possesses higher hardness and strength, making it a popular choice in demanding applications.
For more information about the industry applications of 65Mn steel, please click here.
Chemical Composition
The chemical composition of 65Mn is critical for understanding its mechanical properties and performance in various applications. The key elements are outlined below:
| Element | Composition (%) |
| C | 0.62-0.70 |
| Si | 0.17-0.37 |
| Mn | 0.90-1.20 |
| P | ≤0.025 |
| S | ≤0.025 |
| Cr | ≤0.25 |
| Ni | ≤0.25 |
| Cu | ≤0.25 |
| Fe | Balance |
This precise chemical formulation enables 65Mn to achieve considerable hardness after heat treatment while maintaining good toughness.
Mechanical Properties
The mechanical properties of 65Mn further illustrate its suitability for various applications:
| Property | Value |
| Tensile Strength σb (MPa) | ≥ 980 |
| Yield Strength σ0.2 (MPa) | ≥ 720 |
| Elongation δ5 (%) | ≥ 14 |
| Reduction of area ψ (%) | ≥ 30 |
| Hardness | ≤ 302 HB |
These properties indicate that 65Mn is capable of enduring substantial mechanical stress while exhibiting resilience.
Equivalent Grade
For global contexts, 65Mn has several equivalent grades across various standards, as outlined below:
| Country/Region | Standard |
| China | GB /T 699-2015 |
| USA | AISI/SAE |
| Germany | DIN 17221 |
| Japan | JIS G 4401 |
| Russia | GOST 14959-79 |
| UK | BS 970-1:1983 |
| Europe | EN 10083-2 |
This cross-referencing allows for easier selection and substitution of materials in international projects.
Equivalent Grade Chemical Composition
To further illustrate the similarities between 65Mn and its equivalents, the following table provides the chemical compositions of comparable grades:
| Grade | C | Mn | Si | P | S | Ni | Cr | Cu% |
| 65Mn | 0.62-0.70% | 0.90-1.20% | 0.17-0.37% | ≤0.030% | ≤0.030% | ≤0.030% | ≤0.250% | ≤0.250% |
| 1065 | 0.60-0.70% | 0.60-0.90% | 0.15-0.35% | ≤0.040% | ≤0.050% | ≤0.250% | ≤0.250% | ≤0.250% |
| 1.0605 | 0.62-0.70% | 0.70-1.00% | 0.17-0.37% | ≤0.030% | ≤0.035% | ≤0.030% | ≤0.250% | ≤0.250% |
| SUP 6 | 0.60-0.70% | 0.60-0.90% | 0.15-0.35% | ≤0.030% | ≤0.030% | ≤0.250% | ≤0.250% | ≤0.250% |
| 65G | 0.62-0.70% | 0.90-1.20% | 0.17-0.37% | ≤0.035% | ≤0.035% | ≤0.250% | ≤0.250% | ≤0.250% |
| 080A67 | 0.60-0.70% | 0.60-1.00% | 0.10-0.35% | ≤0.050% | ≤0.050% | ≤0.250% | ≤0.250% | ≤0.250% |
| 65Mn4 | 0.62-0.70% | 0.70-1.00% | 0.17-0.37% | ≤0.035% | ≤0.035% | ≤0.250% | ≤0.250% | ≤0.250% |
This cross-referencing allows for easier selection and substitution of materials in international projects.
Classification
The classification of 65Mn steel can vary based on several parameters, including thickness, surface characteristics, bendability, heat treatment performance, surface hardness, surface treatment, and typical applications:
| Ion | Common Thickness (MM) | Surface Color | Bendability | Heat Treatment Performance | Surface Hardness | Surface Treatment | Typical Applications |
| Cold Rolled and Cut Plate | 0.2-5.0 | Metallic Silver | Good, 90-degree | Better than hot rolled | 160 HV (approx. 0 HRC) | Nickel, chrome plating | Wire cutters, retaining clips |
| Hot Rolled and Cut Plate | 2.0-12 | Bluish-gray | Limited to <60° | Normal | 10-20 HRC | Galvanized, spray-painted | Furniture backs, branch cutters |
| Hot Rolled Medium Plate | 14-60 | Bluish-gray (oxidized scale) | Essentially non-bendable | 20-30 HRC | Medicinal knives, molds |
Cold-rolled steel is characterized by its thinner profile, higher cost, excellent bendability, and superior surface quality. In contrast, hot-rolled steel is moderately thick, more affordable, and has rougher surface characteristics.
Applications Overview
65Mn carbon steel is renowned for its versatility and durability in various cutting tool applications. This high-carbon steel is commonly used in the production of gardening tools, palm knives, and crushing equipment. Its ability to achieve significant hardness after heat treatment allows for sharp, long-lasting edges, making it ideal for tasks that require precision and reliability
Cutting Tools
For cutting tools, 65Mn can achieve a cutting edge hardness of up to 50 HRC and an overall hardness of 48-50 HRC. It exhibits excellent sharpness and toughness, making it suitable for agricultural implements, slicing knives, and crushing blades.
Steel Characteristics
The high carbon content facilitates heat treatment, enhancing hardness but also increasing brittleness. For instance, ordinary hot-rolled 65Mn can crack if bent beyond 60 degrees. The presence of manganese provides a degree of elasticity and fatigue resistance, classifying it as a type of spring steel. 65Mn steel plates produced by Chinese steel mills are recognized in global markets for their wear resistance, comparable to NM400.
Heat Treatment Specifications
Heat treatment is vital for enhancing the performance characteristics of 65Mn. The following outlines the recommended processes:
Quenching Process
- Quenching Temperature: 830℃
- Cooling Medium: Oil quenching (recommended)
- Hardness Requirement: Above 61 HRC
Tempering Process
| Tempering Temperature (°C) | Target Hardness (HRC) | Applicable Range |
| 550-650 | 33-20 | High elasticity, good toughness |
| 400-450 | 45-39 | Good elasticity, high strength |
| 150-250 | 61-55 | Wear-resistant, high hardness knives |
Important Notes
- Temperatures in the 250-400°C and 450-550°C ranges may lead to increased brittleness in the workpiece. Quick cooling is required for tempering at 550-650°C.
Common Heat Treatment Quality Issues and Solutions
Issue 1: Brittleness Post-Treatment
- Solution: Verify that the hardness meets 65Mn specifications, and adjust the heating temperature, cooling medium, and tempering time as necessary.
Issue 2: Maximum Achievable Hardness
- Typically, quenching can achieve hardness levels above 61 HRC, while high-frequency processing may reach up to 65 HRC. Recommended hardness should align with customer requirements.
Issue 3: Differences in Quenching Methods
| Method | Advantages | Disadvantages |
| Water Quenching | Convenient, inexpensive, high hardness | High brittleness |
| Oil Quenching | Good toughness | Higher cost |
0 Comments