The manganese spring steel that hardens deeper than plain 65# — C 0.62–0.70%, Mn 0.90–1.20%, quenched and tempered to 42–50 HRC. Supplied spheroidized for blanking diaphragm springs, circlips, washers and agricultural blades.
65Mn sits between plain carbon spring steel (65#, SAE1065) and alloy spring steel (50CrV4). The extra manganese buys deeper hardening without chromium and vanadium cost — why it dominates medium-section spring applications in China and across Asia.
65# steel (0.30–0.60% Mn) hardens only in thin sections — above ~1.5 mm the core stays soft. 65Mn's 0.90–1.20% Mn pushes the critical diameter up, giving through-hardening in sections up to ~3–4 mm. For diaphragm springs and washers over 1.5 mm thick, 65Mn is the correct call.
65# for thin strip; 65Mn for thicker sections.50CrV4 adds Cr and V for deeper hardening and superior fatigue life — the grade for automotive valve springs and suspension coils under millions of cycles. 65Mn is the leaner, lower-cost choice for flat springs, washers and blades where fatigue cycles are moderate.
65Mn for flat springs & washers; 50CrV4 for high-fatigue coils.SAE1078 (0.72–0.85% C) is optimized for saw blades and cutting edges where maximum hardness matters. 65Mn prioritizes hardenability and toughness over peak hardness — the better choice for springs that must flex without cracking.
65Mn for springs; 1078 for blades and edges.The elevated manganese is the defining feature — it improves hardenability and refines the pearlite structure. Actual heat chemistry confirmed on MTC.
| Element | 65Mn (%) | Notes |
|---|---|---|
| Carbon (C) | 0.62 – 0.70 | Primary hardening and spring-force element |
| Silicon (Si) | 0.17 – 0.37 | Deoxidizer; contributes to elastic limit |
| Manganese (Mn) | 0.90 – 1.20 | Key alloying element — improves hardenability vs. plain 65# |
| Phosphorus (P) | ≤ 0.035 | Residual; controlled for toughness and fatigue |
| Sulfur (S) | ≤ 0.035 | Residual; controlled for shear-face quality |
Reference: GB/T 1222. Values typical per standard, actual confirmed on MTC. Compare with other spring grades in our spring steel standards comparison.
Supplied in two conditions: spheroidized for blanking and forming, or hardened-and-tempered for finished spring properties.
| Condition | Hardness (typ.) | Tensile (typ.) | Typical use |
|---|---|---|---|
| Spheroidized (soft annealed) | ≤ 220 HB | 540 – 650 MPa | Fine blanking, cold forming — part quenched afterwards |
| Hardened & tempered | 42 – 50 HRC | 1,000 – 1,300 MPa | Diaphragm springs, washers, circlips, blades |
Indicative only. Hardness depends on section size, quench medium and tempering. Elevated Mn ensures through-hardening in sections up to ~3–4 mm (oil quench). Typical per standard, actual confirmed on MTC.
65Mn's manganese content is higher than most plain-carbon spring equivalents. Confirm hardenability against your governing standard before substitution.
| Standard | Grade | Notes |
|---|---|---|
| GB (China) | 65Mn | Base reference (GB/T 1222) |
| ASTM (USA) | A682 Grade 1065 (approx.) | Plain carbon spring steel; lower Mn than 65Mn — confirm hardenability |
| JIS (Japan) | SUP6 (approx.) | JIS G4801; Si-Mn spring steel with similar hardenability |
| DIN (Germany) | 65Mn4 (approx.) | Manganese spring steel; confirm against EN standards |
Equivalents are approximate. 65Mn's Mn content (0.90–1.20%) is higher than AISI 1065 (0.30–0.60%), so hardenability differs. For safety-critical springs, confirm full chemistry and hardenability against your governing spec and the MTC.
2.0–4.0 mm 65Mn strip, blanked into diaphragm spring shapes with finger slots, then quenched and tempered to 44–48 HRC. The manganese-enhanced hardenability ensures the full section hardens evenly — critical for consistent diaphragm spring force. See our clutch disc spring guide.
0.3–1.5 mm strip, stamped into wave or conical washer shapes, then Q&T to 45–50 HRC for maximum set resistance. 65Mn is preferred over plain carbon because through-hardening gives uniform spring force across the washer cross-section, preventing permanent set under repeated compression.
0.5–2.0 mm spheroidized strip, fine-blanked to circlip geometry, then hardened and tempered. The clean shear face from the spheroidized condition ensures the circlip seats properly in the groove, and the 65Mn hardness gives the radial spring force needed for secure retention.
1.5–3.0 mm 65Mn strip for sickle sections, mower blades and cutter bars. Blanked and formed in the soft state, then Q&T to 45–50 HRC for a tough, wear-resistant cutting edge that resists chipping in field use. 65Mn's toughness makes it more durable than higher-carbon blade steels in impact-loaded cutting. See our saw blade steel guide.
Full cycle conditioning the carbide structure for clean fine blanking and cold forming. Read more in our spheroidizing guide.
Multi-pass rolling to your gauge tolerance, with controlled surface finish. Thickness tolerances agreed per order and documented on the MTC.
Width tolerance and burr managed on our line — coils for progressive dies, sheets for blanking feeders. Narrow widths from 6 mm.
H&T strip to a specified hardness band for finished spring properties. Flatness managed through tension leveling; decarburization depth controlled and reported.
For 65Mn spring strip and hardened parts: burr height limits by thickness, flatness and camber tolerances, surface roughness Ra, dimensional accuracy and inspection methods — the quality metrics that determine whether your spring and blanking parts meet specification.
These grade families share material, processing or application territory with 65Mn.
65Mn / 50CrV4 / C67S / C75S grades with high elastic limit and fatigue resistance for springs and washers.
SAE1070 / SAE1078 / SK5 grades with higher carbon for saw blades, cutting edges and spring components.
42CrMo / 40Cr grades with Cr-Mo alloying for deep hardening and high fatigue strength.
Include thickness × width, quantity, condition (spheroidized or H&T) and destination port. Reply within one working day.