4J36 Invar with near-zero thermal expansion, MP35N cobalt-nickel for medical and aerospace, 7C27Mo2 premium blade steel and SS716 non-magnetic steel — precision alloys that standard stainless and carbon strip cannot replace. Sourced, processed and documented in Shanghai.
Each material in this range exists because a standard carbon or stainless steel cannot meet the requirement. They are not upgrades — they are the only material that will do the job.
At 35–37% nickel, the iron-nickel lattice undergoes a magnetic volume effect that suppresses thermal expansion near room temperature. No carbon or stainless steel comes close: Invar's CTE is roughly 8–10× lower than carbon steel.
The only choice for dimension-stable precision and optical components.Cobalt-nickel-chromium-molybdenum alloy that combines 1400–1800 MPa tensile with chloride corrosion resistance and biocompatibility. No stainless steel reaches this strength level, and no high-strength carbon steel survives the corrosive environments MP35N handles.
The standard for medical implants and aerospace fasteners.A high-carbon, high-chromium martensitic steel with molybdenum addition, reaching 52–56 HRC after heat treatment. It sits above 4Cr13 in edge retention and corrosion resistance, for premium knives and high-wear blade edges.
The step up from 4Cr13 when edge life justifies the premium.An austenitic steel formulated to maintain low magnetic permeability through forming and service — critical for motor shielding, transformer components and magnetic-sensitive instruments where even mild magnetism would disrupt function.
The choice where magnetic permeability must stay near zero.Four grades, four standards, four defining properties. Equivalents are approximate — special alloys are often specified by a single standard and producer qualification.
| Grade | Standard | Alloy family | Defining property | Primary use |
|---|---|---|---|---|
| 4J36 (Invar) | GB/T 4339 · ASTM F1684 | Fe-Ni low-expansion | CTE ≤1.5×10⁻⁶/°C (20–100°C) | Precision instruments, aerospace, thermostat elements |
| MP35N | ASTM F562 · UNS R30035 | Co-Ni-Cr-Mo | Tensile 1400–1800 MPa + corrosion resistance | Medical implants, aerospace fasteners, high-performance springs |
| 7C27Mo2 | SIS / Uddeholm spec | Martensitic stainless (premium) | 52–56 HRC, Mo-enhanced edge retention | Premium knives, high-wear industrial blades |
| SS716 | GB / producer spec | Austenitic non-magnetic | Low magnetic permeability after forming | Motor shielding, transformer parts, magnetic-sensitive instruments |
7C27Mo2 is also listed on our martensitic stainless strip page — it bridges the stainless and special-alloy ranges. MP35N and SS716 are typically supplied to order; 4J36 and 7C27Mo2 are stocked in standard gauges. All values typical per standard, confirm on MTC.
Chemistry ranges below are typical per the governing standard. For special alloys, chemistry control is tighter than for commodity steels — minor element variations directly affect the defining property (expansion rate, magnetic permeability, strength).
| Element | 4J36 Invar (%) | MP35N (%) | 7C27Mo2 (%) | SS716 (%) |
|---|---|---|---|---|
| Carbon (C) | ≤ 0.05 | ≤ 0.025 | ~0.45 – 0.55 | ≤ 0.12 |
| Silicon (Si) | ≤ 0.30 | ≤ 0.50 | ≤ 1.00 | ≤ 1.00 |
| Manganese (Mn) | ≤ 0.60 | ≤ 0.15 | ≤ 1.00 | ≤ 2.00 |
| Chromium (Cr) | — | 19.0 – 21.0 | ~13.0 – 15.0 | 16.0 – 18.0 |
| Nickel (Ni) | 35.0 – 37.0 | 33.0 – 37.0 | — | 6.0 – 8.0 |
| Cobalt (Co) | ≤ 0.50 | 34.0 – 36.5 | — | — |
| Molybdenum (Mo) | — | 9.0 – 10.5 | ~0.50 – 1.00 | — |
| Phosphorus (P) | ≤ 0.020 | ≤ 0.015 | ≤ 0.035 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.020 | ≤ 0.010 | ≤ 0.030 | ≤ 0.030 |
| Iron (Fe) | Balance | ≤ 1.0 | Balance | Balance |
4J36 per GB/T 4339 / ASTM F1684; MP35N per ASTM F562; 7C27Mo2 per SIS / producer datasheet (indicative); SS716 per GB / producer specification. All values typical per standard — actual heat chemistry confirmed on MTC. "—" indicates the element is not intentionally added or not specified.
For special alloys, the property that matters is often not tensile strength but thermal expansion, magnetic permeability or corrosion resistance. The table below captures each grade's defining parameters.
| Property | 4J36 Invar | MP35N | 7C27Mo2 | SS716 |
|---|---|---|---|---|
| Density (g/cm³) | 8.10 | 8.43 | ~7.75 | ~7.93 |
| Tensile strength (MPa) | 450–550 (annealed) | 790–1000 (annealed) / 1400–1800 (CW+aged) | ≥900 (quenched & tempered) | ≥520 (annealed) |
| Yield strength (MPa) | 250–350 | 300–500 (annealed) / 1200–1600 (CW+aged) | ≥700 | ≥205 |
| Elongation (%) | 30–40 | 40–55 (annealed) / 8–15 (CW+aged) | ≥8 | ≥40 |
| Hardness | ≤160 HB (annealed) | — | 52–56 HRC (quenched) | ≤200 HB |
| CTE (×10⁻⁶/°C, 20–100°C) | ≤ 1.5 | ~12.0 | ~10.5 | ~16.0 |
| Magnetic permeability | Ferromagnetic (Curie ~230°C) | Essentially non-magnetic | Magnetic (martensitic) | Low (austenitic, non-magnetic) |
| Thermal conductivity (W/m·K) | ~13 | ~14 | ~28 | ~16 |
All values typical per standard and producer datasheets — indicative for material selection only. MP35N mechanical properties depend strongly on cold-work reduction and aging treatment; 7C27Mo2 hardness depends on quench and temper cycle. Actual tested values confirmed on MTC per heat and delivery condition. CTE = coefficient of thermal expansion; CW = cold worked.
4J36 strip and sheet for gauge blocks, dial gauge components, coordinate measuring machine fixtures and precision scale arms. The near-zero CTE ensures dimensional readings stay accurate across laboratory temperature swings — carbon steel would drift by microns per degree.
4J36 for satellite and aerospace optical benches, laser mirror mounts and antenna support structures where thermal distortion would disrupt alignment. The low expansion rate keeps optical systems calibrated through launch and orbital temperature cycles.
4J36 as the low-expansion layer in bimetallic strips for thermostats, circuit breakers and temperature-activated switches. Bonded to a high-expansion alloy, the composite bends predictably with temperature — the foundation of mechanical temperature control.
MP35N strip and wire for cardiovascular stents, orthopedic fixation components, surgical instrument springs and implantable electronic housings. The combination of ultra-high strength, chloride corrosion resistance and biocompatibility meets ASTM F562 for permanent implant service.
MP35N for high-strength aerospace fasteners, landing gear springs and actuator components where 1400+ MPa tensile must coexist with salt-spray and stress-corrosion resistance. Cold-worked and aged to the required strength band per drawing.
7C27Mo2 strip for high-end kitchen knives, outdoor cutting tools and industrial slitter blades where 52–56 HRC plus molybdenum-enhanced edge retention outperforms standard 4Cr13. Supplied annealed for blanking, then quenched and tempered by the knife maker.
SS716 non-magnetic strip for motor end shields, transformer clamping structures, magnetic relay housings and current transformer components. The austenitic structure maintains low magnetic permeability after stamping and forming, preventing magnetic field distortion.
SS716 for housings and structural parts in compasses, magnetic sensors, NMR equipment and electron beam instruments where even ferromagnetic fasteners would disrupt measurement. Supplied with magnetic permeability verified on request.
Multi-pass rolling to your gauge for 4J36, 7C27Mo2 and SS716. MP35N rolling is managed to control cold-work reduction for target strength — the reduction percentage directly determines final tensile after aging.
Annealing for 4J36 and SS716 to control grain structure and magnetic properties; solution annealing and aging for MP35N; soft annealing for 7C27Mo2 blanking stock. Cycles matched to the grade and your downstream process.
Slitting to your coil width with managed burr and camber — critical for 4J36 bimetallic elements and MP35N medical components where edge integrity affects fatigue life. Width tolerance documented on the delivery certificate.
Chemistry verified per heat; mechanical and physical properties tested where the standard requires; CTE testing available for 4J36 critical applications. Full Mill Test Certificate issued with every shipment.
The quench-hardening family — 4Cr13, SUS420J2, 2Cr13 — including 7C27Mo2 for premium blades. Compare hardening mechanisms and choose the right stainless family for your part.
View martensitic stainless strip →SUS301 / 12Cr17Ni7 / S30100 work-hardening austenitic strip for springs and connectors — the standard stainless complement to our special alloy range.
View austenitic stainless strip →Carbon and alloy strip in the full cold-rolled range — the commodity complement to special alloys for non-critical structural and forming applications.
View cold-rolled strip →Special alloy MTCs carry more data than commodity steel certificates — chemistry, mechanicals, physical properties and sometimes CTE or magnetic permeability. This guide explains what to verify.
Read the guide →A comprehensive guide to specifying precision strip — tolerances, tempers, surface finishes, edge conditions and documentation requirements — including special alloy considerations.
Read the handbook →Application page covering blade steel selection for surgical and medical instruments — including 4Cr13 and 7C27Mo2, with heat treatment and surface finish guidance.
View application →Include grade, thickness × width, quantity, required standard and destination port. Our engineers reply within one working day.