Spring Steel Strip

What Makes Steel "Spring Steel"

Spring steel is a material category rather than one grade. Selection depends on the finished spring geometry, stress, environment, forming route, heat treatment and validation method.

For cold-rolled strip applications, buyers should define thickness and width tolerances, delivery condition, hardness or mechanical-property requirements, edge, surface and applicable test methods.

Grade Selection Guide

Grade	Composition reference	Hardness reference	Typical candidate uses	Selection note
65Mn	0.62-0.70C, 0.90-1.20Mn	42-50 HRC	General flat springs, retaining rings	Manganese spring steel for general spring components.
51CrV4 (SUP10)	0.47-0.55C, 0.90-1.20Cr, 0.10-0.25V	44-52 HRC	Automotive springs, fatigue-sensitive applications	Chromium-vanadium spring steel for demanding component requirements.
SK5	0.80-0.90C	44-54 HRC (tempered)	Thin flat springs, clips, snap rings	High-carbon grade used for thin spring and clip applications.
SK7	0.60-0.70C	40-48 HRC	Flexible springs, measuring tapes	Lower carbon = more ductility. Better for deep-draw spring forms.
60Si2Mn	0.56-0.64C, 1.50-2.00Si, 0.60-0.90Mn	44-52 HRC	Heavy-duty leaf springs, valve springs	High silicon resists relaxation (sag) at elevated temperatures.

Table values are general grade references, not guaranteed supply values. Verify chemistry, properties and condition against the governing standard and order specification.

Critical Specifications for Spring Strip

Parameter	Our Capability	Why It Matters
Thickness Tolerance	Confirm against the complete RFQ	Required tolerance and measurement method should be stated together.
Thickness Range	0.1mm – 3.0mm	Covers micro-springs (electronics) to heavy flat springs (automotive).
Width	5mm – 800mm	Narrow slit for individual springs, wide for progressive die stamping.
Hardness Uniformity	Specify the target and test method	Acceptance points and sampling frequency should be agreed.
Surface Condition	Bright, polished, blue tempered	Surface defects are fatigue crack initiators. Clean surface = longer life.
Delivery State	Annealed / Quarter-hard / H&T	Annealed for forming then heat treating. H&T for direct use.

Spheroidized Condition for Forming

For applicable high-carbon grades, carbide shape and distribution can affect forming and subsequent heat-treatment response. The required microstructure, inspection method and acceptance limit should be stated in the order rather than assumed from the grade name.

Forming review: Springs may be bent, coiled or stamped in an annealed condition, but the permissible geometry must be validated for the actual material and process.
Uniform heat treatment response: After forming, springs are hardened and tempered to develop elastic properties. A controlled starting microstructure supports a more consistent response, but finished spring properties and reject rates depend on the customer's forming, heat treatment and inspection controls.

Typical Applications

Flat Springs & Leaf Springs

Electrical contacts, battery clips, suspension components, diaphragm springs. Stamped or formed from strip, heat treated to final hardness.

Retaining Rings & Circlips

Internal and external retaining rings (DIN 471/472). Require precise thickness and hardness for consistent snap force and fatigue life in grooves.

Automotive Springs

Clutch, valve, retractor and wiper components may use different spring-steel families. Automotive quality-system and documentation requirements must be specified by the buyer.

Lock Washers & Wave Springs

Belleville washers, wave springs for preload applications. Require consistent elastic modulus and resistance to relaxation under sustained load.

How to Specify Spring Steel Strip

When requesting a quote, provide these parameters for the most accurate recommendation:

Application: What type of spring? (flat spring, retaining ring, wave spring, etc.)
Thickness and width: With tolerance requirements
Delivery condition: Annealed (you heat treat) or hardened & tempered (ready to use)?
Target hardness: If H&T, specify your HRC range
Quantity: Per month or per order
Standards: JIS, DIN, GB, or customer specification?

Not sure which grade fits your spring?
Send the spring drawing or performance requirements together with the governing standard, dimensions, condition, quantity and destination. We will review candidate materials and confirm what can be quoted.

Request Spring Steel Quote