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20.Jan.2026

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Comparison of S65C, SK85, and SK95 for Strip Steel Applications

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Characteristics, Applications, and Material Selection Guidelines for High-Carbon Steels

1. Introduction

Our company offers three grades of high-carbon steel for strip steel applications: S65C, SK85, and SK95.

Because springs, cutting tools, and precision components each require different mechanical properties,

understanding the characteristics of each steel grade is essential for proper material selection.
This article compares the key properties of these steels such as hardness, toughness, fatigue strength, and wear resistance and provides practical guidelines to support engineers and designers in making appropriate material choices.

2. Characteristics Comparison of S65C, SK85, and SK95 (Revised)

Steel Grade	Steel Grade haracteristics (Technical Perspective)	Characteristics (Technical Perspective) Typical Applications
S65C	• Easily forms martensite while being less prone to excessive hardening. • Stable fatigue properties; uniform hardness can be achieved even in thin strips. • Good resistance to press forming and bending, suitable for small bending radii.	Springs, mainsprings, hinges, washers, spacers
SK85	•Higher carbon content, offering a good balance between sharpness and elastic recovery. • Higher toughness than S65C, suitable for components subjected to repeated impact loads. • Relatively small dimensional change after quenching.	Hand saws, cutters, clutch components, washers, spring
SK95	•High-carbon steel capable of achieving the highest quench hardness. • High-temperature tempering reduces toughness; best suited for applications requiring high hardness maintained by low-temperature tempering. • Ideal for cutting tools requiring strong edge retention.	cutters

Polish Finish		Chemical Conposion(%)
JIS	SAE	C	Si	Mn	P	S	Cu	Ni	Cr
S65C		0.60 ~ 0.70	0.15 ~ 0.35	0.60 ~ 0.90	≦0.030	≦0.035	≦0.30	≦0.20	≦0.20
SK85		0.80 ~ 0.90	0.10 ~ 0.35	0.10 ~ 0.50	≦0.030	≦0.035	≦0.30	≦0.20	≦0.20
SK95		0.90 ~ 1.00	0.10 ~ 0.35	0.10 ~ 0.50	≦0.030	≦0.035	≦0.25	≦0.25	≦0.30
SKS51		0.75 ~ 0.85	≦0.35	≦0.50	≦0.030	≦0.030	≦0.25	1.30 ~2.00	0.20 ~ 0.50
SKS5		0.75 ~ 0.85	≦0.35	≦0.50	≦0.030	≦0.030	≦0.25	0.70 ~ 1.30	0.20 ~ 0.50

3. Material Selection Guidelines
3.1 Required Hardness and Edge Retention

Cutting tools, hand saws, and blades (SK95)
Practical hardness range: HRC 50–55 (HV approx. 520–600)
Above HRC 55, the following issues increase significantly:
- Reduced toughness
- Processing cracks (micro-chipping during shearing or punching)
- Chipping and fracture during service
  Therefore, HRC 55 is generally considered the upper design limit.
The advantage of SK95 lies in its ability to easily achieve high hardness, providing stable edge retention and wear resistance around HRC 55.
Components requiring moderate hardness with toughness (SK85)
Practical hardness range: HRC 48–53 (HV approx. 500–560)
Offers a well-balanced combination of sharpness and impact resistance, making it suitable for applications where impact and wear coexist, such as hand saws, clutch components, and washers.
Components requiring high cyclic bending fatigue life (S65C)
Practical hardness range: HRC 42–50 (HV approx. 430–520)
Rather than excessive hardness, stability in cyclic bending fatigue life (S–N characteristics) is the critical factor for these applications.

3.2 Why Hardness Above HRC 60 Is Not Recommended

Although high-carbon steel (SK95) can theoretically reach HRC 60 through quenching:
- Martensite becomes finer, reaching peak hardness while toughness drops sharply.
Hand saws and cutting tools are subjected to combined tensile, bending, and torsional stresses, greatly increasing the risk of brittle fracture.
In thin strip steels (0.1–3.0 mm), fracture during processing becomes more frequent:
- Edge chipping during shearing
- Cracking during slitting
- Microcrack formation during bending
For these reasons, most manufacturing sites operate with HRC 55 as the practical upper limit.

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Comparison of S65C, SK85, and SK95 for Strip Steel Applications

Characteristics, Applications, and Material Selection Guidelines for High-Carbon Steels

1. Introduction

Our company offers three grades of high-carbon steel for strip steel applications: S65C, SK85, and SK95.

Because springs, cutting tools, and precision components each require different mechanical properties,

2. Characteristics Comparison of S65C, SK85, and SK95 (Revised)

Steel Grade

Steel Grade haracteristics (Technical Perspective)

Characteristics (Technical Perspective) Typical Applications

S65C

• Easily forms martensite while being less prone to excessive hardening. • Stable fatigue properties; uniform hardness can be achieved even in thin strips. • Good resistance to press forming and bending, suitable for small bending radii.

Springs, mainsprings, hinges, washers, spacers

SK85

•Higher carbon content, offering a good balance between sharpness and elastic recovery. • Higher toughness than S65C, suitable for components subjected to repeated impact loads. • Relatively small dimensional change after quenching.

Hand saws, cutters, clutch components, washers, spring

SK95

•High-carbon steel capable of achieving the highest quench hardness. • High-temperature tempering reduces toughness; best suited for applications requiring high hardness maintained by low-temperature tempering. • Ideal for cutting tools requiring strong edge retention.

cutters

3. Material Selection Guidelines 3.1 Required Hardness and Edge Retention

Cutting tools, hand saws, and blades (SK95)

Practical hardness range: HRC 50–55 (HV approx. 520–600)

Above HRC 55, the following issues increase significantly:

Reduced toughness

Processing cracks (micro-chipping during shearing or punching)

Chipping and fracture during service Therefore, HRC 55 is generally considered the upper design limit.

The advantage of SK95 lies in its ability to easily achieve high hardness, providing stable edge retention and wear resistance around HRC 55.

Components requiring moderate hardness with toughness (SK85)

Practical hardness range: HRC 48–53 (HV approx. 500–560)

Offers a well-balanced combination of sharpness and impact resistance, making it suitable for applications where impact and wear coexist, such as hand saws, clutch components, and washers.

Components requiring high cyclic bending fatigue life (S65C)

Practical hardness range: HRC 42–50 (HV approx. 430–520)

Rather than excessive hardness, stability in cyclic bending fatigue life (S–N characteristics) is the critical factor for these applications.

3.2 Why Hardness Above HRC 60 Is Not Recommended

Although high-carbon steel (SK95) can theoretically reach HRC 60 through quenching:

Martensite becomes finer, reaching peak hardness while toughness drops sharply.

Hand saws and cutting tools are subjected to combined tensile, bending, and torsional stresses, greatly increasing the risk of brittle fracture.

In thin strip steels (0.1–3.0 mm), fracture during processing becomes more frequent:

Edge chipping during shearing

Cracking during slitting

Microcrack formation during bending

For these reasons, most manufacturing sites operate with HRC 55 as the practical upper limit.

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Inquriy

Steel Grade
haracteristics (Technical Perspective)

Characteristics (Technical Perspective)
Typical Applications

• Easily forms martensite while being less prone to excessive hardening.
• Stable fatigue properties; uniform hardness can be achieved even in thin strips.
• Good resistance to press forming and bending, suitable for small bending radii.

•Higher carbon content, offering a good balance between sharpness and elastic recovery.
• Higher toughness than S65C, suitable for components subjected to repeated impact loads.
• Relatively small dimensional change after quenching.

•High-carbon steel capable of achieving the highest quench hardness.
• High-temperature tempering reduces toughness; best suited for applications requiring high hardness maintained by low-temperature tempering.
• Ideal for cutting tools requiring strong edge retention.

3. Material Selection Guidelines
3.1 Required Hardness and Edge Retention

Chipping and fracture during service
Therefore, HRC 55 is generally considered the upper design limit.