We are Riddhi Siddhi Impex, a Mumbai-based Stainless Steel 301 Shims manufacturer and supplier, established in 2002. We precision-slit UNS S30100 shim stock manufactured to ASTM A240 / ASME SA-240 and ASTM A666 in thicknesses from 0.03 mm to 5 mm, across every temper from Soft to Full Hard. Our ISO 9001, 14001, and 45001-certified company has a supply capacity of 400 to 500 tons per month.
Stainless Steel 301 Shims are thin, flat spacers slit from an austenitic 17Cr-7Ni alloy that work-hardens fast. During cold rolling, the metastable austenite converts to martensite, so tensile strength climbs from around 515 MPa annealed to 1275 MPa at Full Hard. That behaviour makes Type 301 the grade of choice for spring-tempered and fatigue-loaded stainless steel shims. Material density is firmly at 7.88 g/cm³. Typical uses include stamping into flat springs, diaphragm valves, Belleville washers, and high-fatigue wear spacers for automotive or aerospace assemblies.
We produce every 301 shim in-house on our own slitting lines. Material is supplied to ASTM A240 chemistry requirements and ASTM A666 temper requirements, in any temper from Soft through Quarter, Half, Three-Quarter, and Full Hard. Buyers can specify BA, 2B, Matte, or Skin Pass finishes, with EN 10204 Type 3.1 or 3.2 certificates available on request.
Temper sets the strength and springback of a 301 shim by controlling how far the strip has been cold rolled below its annealed state. We stock Type 301 shims in all five conditions that ASTM A666 defines: Soft (Annealed), Quarter Hard, Half Hard, Three-Quarter Hard, and Full Hard. Each of these tempers carries a standard tensile and hardness minimum, so the figures on our mill test certificates trace straight back to the specification. Harder mill conditions such as spring and extra full hard are available on request, rolled to tensile ranges agreed at order stage rather than to an A666 table. The right choice comes down to how far the shim must flex and recover under load.
Annealed 301 sits at its lowest strength, 515 MPa (75 ksi) minimum tensile with 40% elongation and a hardness of ≈ 85 HRB (typical). This is the temper that slits cleanest and interleaves flat, so we reach for it when a customer needs shims that lie without coil set across a wide blank. It folds and deep-draws without cracking, which lets stampers form it into laminated shim packs, gasket spacers, and align-and-peel sets. Annealed 301 also sits closest to non-magnetic, a point that matters for shims placed near sensors. Strength under sustained clamp load is modest, so where a spacer must hold preload, we move the buyer to a harder temper.
Quarter hard is the temper we quote first when a stamping shop wants more stiffness than annealed gives but still needs to form the part without splitting. ASTM A666 sets its minimum tensile at 860 MPa (125 ksi), with 25% elongation and 25 HRC (typical) hardness. The added strength holds a shim flatter under moderate bolt load while leaving enough ductility for light bends and piercing. Buyers fit it into bracket spacers, adjustment shims, and low-deflection washers where a soft shim would relax. It is the balanced middle option many first-time buyers settle on once they describe the job.
Half hard solves the complaint we hear most about softer shims: spacers that flatten out and lose clamp load after a few thermal cycles. Rolled to a minimum tensile of 1035 MPa (150 ksi) with 760 MPa (110 ksi) yield and 18% elongation per A666, it keeps its set far better under repeated loading. Forming is now limited to gentle bends, so parts are usually blanked rather than deep drawn. Diaphragm backers, valve spacers, and preload shims in vibrating assemblies are the common calls. Its ≈ 32 HRC typical hardness gives wear resistance a soft spacer cannot match.
Spring-loaded assemblies that must return to an exact gap after every stroke are where three-quarter hard 301 earns its place. The temper reaches 1205 MPa (175 ksi) minimum tensile, 930 MPa (135 ksi) yield, and 37 HRC (typical), with elongation down to 12%. At this hardness the strip is close to its forming limit, so we supply it flat or to simple radii and flag tight bends at the order desk. Belleville-style washers, flat springs, and fatigue spacers in actuator stacks use it for the springback. Where a design also needs guaranteed elongation at full strength, 301 stays the right grade to specify rather than a leaner alloy.
Full hard is the strongest condition A666 tabulates for Type 301, and our EN 10204 3.1 certificate records its 1275 MPa (185 ksi) minimum tensile, 965 MPa (140 ksi) yield, and 9% elongation against that standard, with hardness reported for information (typically ≈ 41 HRC). The strip is fully work-hardened, so cold working forms strain-induced martensite and the shim turns noticeably magnetic. Forming is restricted to flat parts and very light radii, and anything sharper will crack. It suits high-fatigue wear spacers, piston-ring shims, and flat springs that see high cycle counts. For strength beyond this, spring and extra full hard 301 exist as mill tempers, rolled to tensile ranges agreed at order and recorded on the certificate rather than drawn from A666.
We provide ASTM A240 Type 301 Shims in the full temper range, with four surface finishes and three edge options.
| Parameter | Details |
|---|---|
| Standard | ASTM A240 / ASME SA-240 and ASTM A666 |
| Thickness | 0.03 mm to 5 mm |
| Width | 3 mm to 2000 mm |
| Width Tolerance | ±0.1 mm |
| Temper | Soft (Annealed), 1/4 Hard, 1/2 Hard, 3/4 Hard, Full Hard |
| Surface Finish | BA (Bright Annealed), 2B, Matte, Skin Pass |
| Edge | Slit edge, Deburred edge, Round edge |
| Supply Form | Cold Rolled |
Chromium and nickel set this grade apart. Type 301 Shims carry 16.0 to 18.0% chromium and a lean 6.0 to 8.0% nickel, and that low nickel drives the high work-hardening rate. The full composition per ASTM A240 appears below.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.15 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 0.75 max |
| Chromium (Cr) | 16.0 to 18.0 |
| Nickel (Ni) | 6.0 to 8.0 |
| Nitrogen (N) | 0.10 max |
301 Spring Temper Shims cover a wide strength band. Cold work raises minimum tensile strength from 515 MPa annealed to 1275 MPa at Full Hard, while elongation falls from 40% to 9%. Each temper is defined by tensile strength and Rockwell hardness per ASTM A666, so buyers match spring-back and fatigue needs precisely.
| Temper | Tensile Strength (min) | Yield Strength 0.2% (min) | Elongation (min) | Hardness |
|---|---|---|---|---|
|
Soft (Annealed)
|
515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% | 85 HRB max |
|
1/4 Hard
|
860 MPa (125 ksi) | 515 MPa (75 ksi) | 25% | 25 HRC min |
|
1/2 Hard
|
1035 MPa (150 ksi) | 760 MPa (110 ksi) | 18% (above 0.38 mm) | 32 HRC min |
|
3/4 Hard
|
1205 MPa (175 ksi) | 930 MPa (135 ksi) | 12% | 37 HRC min |
|
Full Hard
|
1275 MPa (185 ksi) | 965 MPa (140 ksi) | 9% | 41 HRC min |
International buyers can cross-reference UNS S30100 Shims against their regional standard below. Our SUS 301 Shims match every designation listed here.
| Country / Standard | Designation |
|---|---|
| USA (UNS) | S30100 |
| Europe (EN) | X10CrNi18-8 |
| Germany (W.Nr) | 1.4310 |
| Japan (JIS) | SUS 301 |
| China (GB) | 06Cr17Ni7 |
These 4 industries specify most of the 301 SS Shims we slit. Buyers select the grade for spring action, fatigue resistance, or dimensional stability under load.
Aerospace assemblers fit 301 shims in actuator housings, gyroscope mounts, and instrument stacks where clearances must hold through vibration. The grade's high fatigue resistance suits high-cycle service. A shim slit to ±0.1 mm installs ready, keeping stack-up calculations accurate.
Automotive plants use 301 shims in gasket packs, spring assemblies, and precision spacing between mating faces. The grade's spring-back holds preload under repeated thermal and mechanical cycling. Harder tempers resist deformation where a softer spacer would relax, keeping clamp loads stable.
Spring makers and bellows fabricators specify Half Hard to Full Hard 301 shims for their strength and fatigue life. The work-hardened structure returns to shape after flexing, which matters in diaphragms and piston rings. Tight thickness control keeps spring rates consistent.
Instrumentation builders fit thin 301 shims to align sensors, set air gaps, and pack connector stacks. Annealed shims stay nearly non-magnetic, while cold-worked tempers turn slightly magnetic through strain-induced martensite. The temper choice matches the magnetic requirement.
Export orders leave from Mumbai and Taloja, packed in wooden cases or on pallets for sea freight.
| Parameter | Details |
|---|---|
| Packaging | Wooden cases, pallet packing |
| Incoterms | FOB, CIF, CFR, EXW Mumbai |
| Dispatch Points | Mumbai and Taloja warehouses |
| Standard Lead Time | 4 to 5 days |
| Urgent Dispatch | 2 to 3 days |
| Payment Terms | Advance, credit, LC |
| Certification | EN 10204 Type 3.1 / 3.2 on request |
The price of Stainless Steel 301 shims in India typically run around ₹200-₹350 per kg for standard items, with premium or precision shims up to about ₹350-₹450 per kg and for global market it range around $4.20-$5.40 per kg. Temper, thickness, width, quantity, and finish all move the figure. Call or WhatsApp us for today's rate.
We slit 301 shim stock from 0.03 mm to 5 mm thick and to any width between 3 mm and 2000 mm, held to ±0.1 mm. Anything thinner falls under our Stainless Steel 301 foils range.
We supply SS 301 Shims across the full temper ladder: Soft (Annealed), Quarter Hard, Half Hard, Three-Quarter Hard, and Full Hard. Each temper is specified by tensile strength and Rockwell hardness per ASTM A666.
SS301 Shims are close to non-magnetic in the annealed condition. Cold working to harder tempers forms strain-induced martensite, which makes the shim slightly magnetic, so the temper you choose changes the magnetic response.
The main difference between grade 301 Shims hold lower nickel at 6 to 8% than 304, giving 301 a higher work-hardening rate and greater tensile strength in cold-worked tempers. 304 offers better general corrosion resistance when annealed.
You can source Stainless Steel 301 Shims in India from us at Riddhi Siddhi Impex. Our Mumbai warehouse holds 301 shim stock on the shelf, ready for dispatch. As a manufacturer, stockist, and exporter, we serve buyers across India and export overseas. For quotation requests, please reach us via phone or WhatsApp.
