Les portes à volets roulants dépendent fortement de leurs systèmes à ressorts pour fonctionner en toute sécurité et en douceur.. Qu'il soit utilisé dans les entrepôts commerciaux, garages, or industrial loading bays, the spring is responsible for counterbalancing the door’s weight — allowing it to open and close effortlessly. Because these springs experience constant torsion, cycling, and stress, selecting the right steel strip is critical.
In this blog, we analyze the most commonly used materials for roller shutter springs and explain which steel strip delivers the best performance, durability, and stability.
1. What Makes a Steel Strip Suitable for Roller Shutter Springs?
Roller shutter springs must withstand:
- High torsional stress
- Continuous cycling (tens of thousands of opening/closing cycles)
- Fatigue loading over long periods
- Occasional overload or impact
- Corrosion in outdoor environments
Therefore, an ideal steel strip should offer:
- High elastic limit
- Excellent fatigue resistance
- Strong tensile strength
- Reliable toughness
- Consistent hardness
- Stable microstructure after heat treatment
This eliminates ordinary mild steel and points to special high-carbon spring steels.
2. Common Steel Grades Used for Roller Shutter Door Springs
The three most widely used steel grades in global production are:
① 65Mn — High-Carbon Manganese Spring Steel
65Mn is one of the most popular choices for shutter springs, due to its:
- High elasticity
- Excellent tensile strength
- Good fatigue resistance
- Strong wear resistance
- Stable performance after quenching and tempering
It offers a great balance between performance and cost.
Typical properties for spring use:
- Hardness: 42–48 HRC
- Tensile strength: 1500–1700 MPa
- Elongation: Good for repeated torsional cycling
This makes 65Mn extremely suitable for medium to heavy-duty roller doors.
② C75S — High-Carbon Steel with Stable Elasticity
C75S (0.75% carbon) is another reliable grade for spring manufacturing.
Advantages include:
- Strong elasticity after tempering
- Predictable and consistent mechanical properties
- High strength-to-weight ratio
- Lower cost than alloy steels
This grade is widely used for:
- Residential garage door springs
- Medium-load shutter systems
Although its fatigue resistance is slightly lower than 65Mn, C75S remains a highly economical and stable option.
③ SK85 / SAE1075 — Premium Spring Steel for High-Cycle Applications
SK85 (or equivalent 1075 steel) is a Japanese-grade high-carbon steel with:
- Exceptional hardness uniformity
- Improved fatigue performance
- Good tempering response
It is often selected by manufacturers who require very high cycle life, such as commercial roller shutters used 50–100 times per day.
3. Which Steel Strip Is the Best Choice?
For most roller shutter door springs:
✅ 65Mn is the best all-round performer.
It offers the highest combination of:
- Elasticity
- Strength
- Fatigue resistance
- Durability
- Cost efficiency
Its manganese alloy content improves hardenability, allowing the spring to maintain performance even after long-term torsional stress.
For cost-efficient residential shutter systems:
⭐ C75S is an excellent and stable choice.
- Reliable elasticity
- Good performance for moderate loads
- Affordable pricing
- Easy to process and heat treat
For high-end commercial or industrial shutters with very high cycle requirements:
? SK85 / 1075 provides premium performance.
- Higher fatigue life
- Tighter hardness tolerance
- More stable microstructure
4. Why Heat Treatment Matters More Than the Grade Alone
Even the best steel grade performs poorly without proper heat treatment.
Critical heat treatment steps include:
- Controlled quenching
- Uniform tempering
- Precise hardness range (usually 42–48 HRC)
- Avoiding decarburization
- Ensuring straightness and consistent thickness
Suppliers like Jiaxiao MTC specialize in producing hardened & tempered spring steel strips with:
- Stable hardness
- High dimensional accuracy
- Clean, bright surface
- Excellent fatigue performance
These qualities directly impact spring life and customer safety.
5. Final Recommendation
After comparing all grades:
? Best Overall Choice: 65Mn Spring Steel Strip
Ideal for most roller shutter applications due to high fatigue resistance and strong elasticity.
? Best Cost–Performance Choice: C75S Steel Strip
Suitable for residential and medium-load shutters.
? (Premium Option) SK85 / SAE1075 Steel Strip
For industrial environments with heavy cycling demands.
Conclusion
Choosing the right steel strip for roller shutter door springs is essential to ensure long service life, reliability, and smooth door operation. While several materials can be used, 65Mn stands out as the most versatile and dependable grade, delivering outstanding performance across a wide range of shutter systems.
Manufacturers like Jiaxiao MTC provide high-quality spring steel strips in 65Mn, C75S, SK85, and other grades — all processed with precise heat treatment and strict quality control to meet global industry demands.
