JIS G4305 SUS440A Steel Plate | 440A Stainless Steel
What is JIS G4305 SUS440A Steel Plate?
As a stainless steel supplier and China mill-direct exporter, SHH STEEL supplies JIS G4305 SUS440A Steel Plate, also known as 440A stainless steel. SUS440A is a high-carbon martensitic grade of JIS G4305:2021, the Japanese Industrial Standard for cold-rolled stainless steel plate, sheet and strip. It contains 0.60 – 0.75 % carbon and 16.00 – 18.00 % chromium, and is supplied annealed for machining and forming, then hardened by the user.
JSSA describes SUS440A as having higher quenched hardness than SUS420J2 and better corrosion resistance than SUS420J2. GB/T 20878 cross-references it to UNS S44002, to the Chinese grade 68Cr17 (ISC S44070) and to EN 1.4040 in brackets. Type 440A is not listed in ASTM A240; compare JIS G4305 SUS420J2 steel plate and ASTM A240 Type 420 sheet and plate.
This page summarises the requirements of JIS G4305:2021 for SUS440A: chemical composition, mechanical properties, surface finishes, standard sizes and the informative heat-treatment conditions of Annex JA. Hot-rolled plate of the same grade is ordered to JIS G 4304:2021, which also lists SUS440A. SHH STEEL quotes either standard and confirms the edition named on the drawing before an order is placed.
SUS440A material specification and SHH STEEL supply scope
| Item | JIS G4305:2021 requirement | SHH STEEL supply |
|---|---|---|
| Standard | JIS G 4305:2021, cold-rolled stainless steel plate, sheet and strip | Full compliance; JIS G 4304:2021 for hot-rolled plate |
| Grade | SUS440A (martensitic) | Confirmed by heat analysis on the certificate |
| Standard plate sizes (Table 16) | Thickness 0.30 – 20.0 mm; 1 000 × 2 000, 1 219 × 2 438, 1 219 × 3 048 and 1 524 × 3 048 mm | Other sizes by agreement, as Table 16 allows |
| Standard strip thickness (Table 17) | 0.30 – 6.0 mm | Coil and slit strip |
| Surface finish (Table 15) | No.2D, No.2B, BA, HL; polished finishes by the manufacturer’s method | Finish written into the mill order |
| Inspection document | JIS G 0415, inspection certificate 3.1, unless otherwise specified | 3.1 standard; 3.2 with third-party witness on request |
Mechanical properties in JIS G4305 apply to thickness 0.30 mm and above, and the standard notes that properties after heat treatment carried out by the user are not specified. Hardness after quenching and tempering is specified in Table 13; the annealed properties are in Table 12.
Chemical composition of JIS G4305 SUS440A (heat analysis, %)
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.60 – 0.75 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulphur (S) | ≤ 0.030 |
| Nickel (Ni) | ≤ 0.60 |
| Chromium (Cr) | 16.00 – 18.00 |
| Molybdenum (Mo) | ≤ 0.75 |
The high carbon content gives the grade its hardenability; chromium of 16 – 18 % gives better corrosion resistance than the 13 % chromium martensitic grades.
Mechanical properties of SUS440A in the annealed condition (JIS G4305 Table 12) and after quenching and tempering (Table 13)
| Property | Requirement |
|---|---|
| 0.2 % proof stress (annealed) | ≥ 245 N/mm² |
| Tensile strength (annealed) | ≥ 590 N/mm² |
| Elongation (annealed) | ≥ 15 % |
| Hardness (annealed) | ≤ 255 HBW or ≤ 25 HRC |
| Hardness (quenched and tempered) | ≥ 40 HRC |
The quenched-and-tempered hardness in Table 13 is measured on test pieces heat treated to Annex JA conditions; parts made by the customer depend on their own heat treatment.
Surface finishes for SUS440A sheet and plate
| Finish (Table 15) | Description |
|---|---|
| No.2D | Cold rolled, heat treated and pickled (or equivalent); may include a final light pass on dull rolls |
| No.2B | Cold rolled, heat treated, pickled, then lightly cold rolled for a suitable lustre |
| BA | Bright annealed after cold rolling |
| HL | Polished with abrasive of suitable grit to give continuous polishing lines |
JIS G4305 leaves polished finishes such as No.3, No.4, #240, #320 and #400 to the manufacturer’s method, so SHH STEEL writes the finish, the grit and any protective film into the purchase order. For martensitic sheet, No.2D and No.2B are the usual finishes.
Heat treatment and delivery condition of SUS440A
| Treatment | Condition (Annex JA, Table JA.4) |
|---|---|
| Annealing | 800 – 900 °C slow cooling, or about 750 °C rapid cooling |
| Quenching | 1 010 – 1 070 °C, rapid cooling |
| Tempering | 150 – 400 °C, air cooling |
Annex JA is informative. The annealed condition is the delivery condition; quenching and tempering are normally carried out by the user after machining.
Table 19 of JIS G4305 gives a basic mass of 7.70 kg/(mm·m²) for SUS440A, which is used to calculate plate weight (equivalent to a density of 7.70 g/cm³). Lead time from the mill is normally 30 – 40 days after order confirmation, depending on size, finish and rolling schedule.
Key characteristics of 440A stainless steel
- Carbon 0.60 – 0.75 % with 16 – 18 % chromium.
- JSSA: higher quenched hardness and better corrosion resistance than SUS420J2.
- Annealed hardness ≤ 255 HBW for machining; ≥ 40 HRC after quenching and tempering.
- Not listed in ASTM A240.
- Magnetic in all conditions.
- Density 7.70 g/cm³ (JIS G4305 Table 19).
SUS440A equivalent grades
| System | Grade | Comment |
|---|---|---|
| UNS | S44002 (Type 440A) | Cross-referenced in GB/T 20878 Table C.1; not in ASTM A240 |
| China | 68Cr17, ISC S44070 | Cross-referenced in GB/T 20878 Table C.1 |
| EN | (1.4040), shown in brackets | Related number |
For lower-carbon martensitic sheet, see JIS G4305 SUS420J1 steel plate.
Applications of JIS G4305 SUS440A Steel Plate
The Japan Stainless Steel Association lists the main uses of SUS440A as:
- Bearings
- Valves
- Cutlery and blades
SHH STEEL supplies SUS440A in the annealed condition; final hardening is done by the customer.
SUS440A compared with related JIS G4305 grades
The table compares SUS440A with the JIS G4305:2021 grades that buyers most often consider alongside it. Chemistry is taken from Tables 3 – 7 and the minimum mechanical properties from Tables 8 – 14 of the standard, all in the condition in which the grade is normally supplied.
| JIS G4305 grade | Cr % | Ni % | Mo % | Other | 0.2 % proof stress, N/mm² | Tensile, N/mm² | Elongation, % |
|---|---|---|---|---|---|---|---|
| JIS G4305 SUS410 | 11.50 – 13.50 | – | – | C ≤ 0.15 | 205 | 440 | 20 |
| JIS G4305 SUS420J1 | 12.00 – 14.00 | – | – | C 0.16 – 0.25 | 225 | 520 | 18 |
| JIS G4305 SUS420J2 | 12.00 – 14.00 | – | – | C 0.26 – 0.40 | 225 | 540 | 18 |
| SUS440A | 16.00 – 18.00 | ≤ 0.60 | ≤ 0.75 | C 0.60 – 0.75 | 245 | 590 | 15 |
Values are for the annealed condition (Table 12). SUS440A has the highest carbon and chromium of the martensitic grades and the highest annealed tensile strength. SHH STEEL can quote the grades in this table side by side when a buyer is still choosing between them.
SUS440A to JIS G4305 (cold rolled) or JIS G4304 (hot rolled)?
SUS440A is listed in both JIS G4305:2021 (cold-rolled plate, sheet and strip) and JIS G4304:2021 (hot-rolled plate, sheet and strip). The chemistry and the mechanical property tables are the same in both standards, but the product range, finish and tolerances differ:
| Item | JIS G4305 (cold rolled) | JIS G4304 (hot rolled) |
|---|---|---|
| Standard plate thicknesses (Table 16) | 0.30 – 20.0 mm | 2.0 – 35.0 mm |
| Standard plate sizes | 1 000 × 2 000, 1 219 × 2 438, 1 219 × 3 048, 1 524 × 3 048 mm | Same four sizes |
| Standard strip thicknesses (Table 17) | 0.30 – 6.0 mm | 2.0 – 9.0 mm |
| Surface finish (Table 15) | No.2D, No.2B, BA, HL | No.1 (hot rolled, heat treated and pickled) |
| Plate thickness tolerance | Table 20, or ET / ST on request | Classes A, B or C (Tables 20 – 22); B and C use an addition to thickness for calculated mass |
As a rule, thin sheet and anything that needs a bright or brushed surface is ordered to JIS G4305, while heavier plate for fabrication is ordered to JIS G4304. Sizes outside the tables are possible by agreement in both standards. SHH STEEL confirms which standard and finish suit the part before quoting.
Corrosion resistance of SUS440A
A common way to rank resistance to pitting is the pitting resistance equivalent number, PREN = %Cr + 3.3 × %Mo + 16 × %N. Calculated from the JIS G4305 limits, SUS440A has a PREN of about 16.0 at the minimum of every range and about 20.5 at the maximum. PREN is a ranking tool, not a guarantee of performance in a given environment, and actual heats normally sit between these values; the certificate analysis gives the real figure for each heat. SHH STEEL can calculate the PREN of the heat offered from its certificate before the order is confirmed.
JSSA rates the corrosion resistance of SUS440A higher than SUS420J2, because of its 16.00 – 18.00 % chromium. Martensitic grades are nonetheless less corrosion resistant than austenitic grades, and their best corrosion resistance is reached in the hardened condition with a clean, ground or polished surface.
Where resistance to intergranular corrosion must be demonstrated, clause 7 of JIS G4305 lets the purchaser specify one of four test methods: JIS G 0571 (oxalic acid etch test), JIS G 0572 (ferric sulphate – sulphuric acid test), JIS G 0573 (65 % nitric acid test) or JIS G 0575 (copper sulphate – sulphuric acid test). One test piece is taken per heat and heat-treatment lot. SHH STEEL writes the chosen method and acceptance criterion into the mill order when a project requires it.
Welding, forming and machining SUS440A
SUS440A is not normally used for welded structures: its high carbon content makes the weld and heat-affected zone very hard and prone to cracking. Where welding cannot be avoided, preheating and post-weld heat treatment are needed and the procedure should be qualified. The grade is supplied annealed (≤ 255 HBW) so that it can be cut, machined and formed before hardening.
Hardening follows Annex JA Table JA.4: quench from 1 010 – 1 070 °C with rapid cooling and temper at 150 – 400 °C with air cooling, to reach at least 40 HRC (Table 13). Grinding after hardening should be done with care to avoid overheating the surface, which would soften it locally. Because hardness and toughness depend on the tempering temperature, the part drawing should state the required hardness range rather than only the grade, so that the heat treater can choose the tempering temperature within the 150 – 400 °C range of the annex.
SHH STEEL can deliver SUS440A cut to size, bevelled or pre-formed through its processing partners, so that the fabricator receives parts ready for welding.
Dimensional tolerances for SUS440A plate and sheet (JIS G4305)
JIS G4305:2021 clause 9 sets the tolerances for cold-rolled plate, sheet and strip, and SHH STEEL checks thickness at the positions the standard defines before shipment. Thickness tolerances for plate are given in Table 20 and depend on thickness and width:
| Thickness (mm) | Width < 1 250 mm | Width 1 250 – 1 600 mm |
|---|---|---|
| 0.30 – < 0.60 | ± 0.05 | ± 0.08 |
| 0.60 – < 0.80 | ± 0.07 | ± 0.09 |
| 0.80 – < 1.00 | ± 0.09 | ± 0.10 |
| 1.00 – < 1.25 | ± 0.10 | ± 0.12 |
| 1.25 – < 1.60 | ± 0.12 | ± 0.15 |
| 1.60 – < 2.00 | ± 0.15 | ± 0.17 |
| 2.00 – < 2.50 | ± 0.17 | ± 0.20 |
| 2.50 – < 3.15 | ± 0.22 | ± 0.25 |
| 3.15 – < 4.00 | ± 0.25 | ± 0.30 |
| 4.00 – < 5.00 | ± 0.35 | ± 0.40 |
| 5.00 – < 6.00 | ± 0.40 | ± 0.45 |
| 6.00 – < 8.00 | ± 0.50 | ± 0.50 |
| 8.00 – < 10.0 | ± 0.60 | ± 0.60 |
| 10.0 – < 16.0 | ± 0.70 | ± 0.70 |
| 16.0 – 25.0 | ± 0.80 | ± 0.80 |
Tighter thickness tolerances can be ordered with the symbols ET (Table 22) or ST (Table 23), and narrower width tolerances with EW (Table 26). Plate width tolerance (Table 24) is +10 / 0 mm for lengths up to 3 500 mm, and plate length tolerance (Table 27) is +10 / 0 mm for thickness under 10 mm and lengths up to 3 500 mm. Flatness is measured on request: Table 28 allows 15 – 20 mm per 3 500 mm length, or 3 – 6 mm when the special flatness symbol EF is ordered.
For hot-rolled SUS440A plate ordered to JIS G 4304, the tolerances of that standard apply. SHH STEEL states the tolerance symbols on the quotation so that the buyer knows exactly which table the plate will be measured against.
Testing, inspection and marking of SUS440A
Clause 11 of JIS G4305 sets the test rules. Chemical analysis follows JIS G 0404 and JIS G 0320, and a product (check) analysis to JIS G 0321 can be requested by the purchaser. For mechanical tests, one sample is taken from plate or strip of the same heat and the same heat-treatment condition, and one test piece is used for each test.
- Tensile test to JIS Z 2241 at 23 ± 5 °C, using test piece No. 4, No. 10 or No. 13B (No. 14A, 14B or 5 also allowed).
- Hardness test to JIS Z 2243-1 (Brinell), JIS Z 2244-1 (Vickers) or JIS Z 2245 (Rockwell), at 23 ± 5 °C.
- Bend test to JIS Z 2248 where the grade has a bend requirement; the manufacturer may omit it, but the material must still meet it, and it must be done if the purchaser asks.
- Inspection of chemistry, mechanical properties, surface finish, dimensions and appearance under clause 12; corrosion resistance only when specified.
Under clause 13 each plate or bundle is marked with the grade symbol, dimensions, any special tolerance or flatness symbols (ET, ST, EW, EF), the surface finish, the heat-treatment symbol where applicable, the manufacturer’s name or mark, and the heat or inspection number. Clause 14 makes the inspection document JIS G 0415 type 3.1 unless another type is ordered; SHH STEEL checks the marking against the certificate before shipment, and a third-party inspector arranged by SHH STEEL can witness the tests when a 3.2 document is required.
How to order SUS440A plate and sheet
A complete enquiry avoids delays and wrong deliveries. For SUS440A we recommend stating:
- Standard and edition: JIS G 4305:2021 (cold rolled) or JIS G 4304:2021 (hot rolled), grade SUS440A.
- Product form: plate, sheet, coil or strip; thickness, width and length, or coil inner diameter and weight.
- Tolerance and flatness symbols if tighter than standard (ET, ST, EW, EF).
- Surface finish from Table 15 (No.2D, No.2B, BA, HL) or a polished finish with grit and protective film.
- Heat-treatment condition, and any intergranular corrosion test method (JIS G 0571 – 0575).
- Inspection document type (JIS G 0415 3.1 by default, 3.2 if third-party witness is needed).
- Any dual certification required, for example to ASTM A240 or EN 10088-2, and any product analysis or PMI.
- Packing, marking and destination port; SHH STEEL can add customer marking or bar codes on request.
SHH STEEL reviews every enquiry against these points and confirms in writing anything that the mill cannot meet before the order is placed.
How to calculate the weight of SUS440A plate
Table 18 of JIS G4305 calculates plate mass from the basic mass in Table 19, which for SUS440A is 7.70 kg per mm of thickness per m² of area. The basic mass is multiplied by the thickness in millimetres to give the unit mass in kg/m², then by the plate area in m², and the result is rounded as the table specifies.
| Example | Calculation | Mass |
|---|---|---|
| SUS440A, 3.0 × 1 219 × 2 438 mm | 7.70 × 3.0 × (1.219 × 2.438) | about 68.7 kg per sheet |
Invoiced weight may be calculated (theoretical) or actual (weighed), and this should be agreed at the order. SHH STEEL states which method is used on the quotation, and the SHH STEEL packing list shows both the calculated and the actual weight of each bundle.
Why choose SHH STEEL for SUS440A
As a SUS440A supplier, we find that buyers usually worry less about price than about getting the right material on time. The table below lists the concerns we hear most often and how SHH STEEL deals with each one.
| Buyer concern | Risk | How SHH STEEL handles it |
|---|---|---|
| Wrong condition | Hardened material is delivered and cannot be machined. | Annealed delivery and the hardness limit are written into the order. |
| Carbon level | Carbon near 0.60 % gives lower hardness after hardening. | Carbon is checked on the certificate. |
| Edge cracking | Shearing high-carbon sheet causes cracks. | Cutting method is agreed; SHH STEEL can cut to size. |
| Minimum order | Mills set high minimums for less common grades. | Orders are consolidated so smaller lots can join a mill rolling where the mill makes the grade. |
| Delivery tracking | Delays at rolling, annealing or testing are found too late. | A dedicated person follows the schedule and reports progress at each stage. |
SHH STEEL also offers steel cutting services, bending and forming services, a third-party testing service with partner laboratories, and a worldwide shipping service. See our full range of stainless steel sheets and plates.
FAQ
- What is SUS440A equivalent to?
- GB/T 20878 Table C.1 cross-references SUS440A to UNS S44002 (Type 440A), to the Chinese grade 68Cr17 (ISC S44070) and to EN 1.4040 in brackets. Type 440A is not listed in ASTM A240, so American purchase orders for flat product usually name the UNS number or a proprietary specification. Any substitution must be approved by the designer. SHH STEEL compares the limits and can supply SUS440A or 68Cr17 with the matching certificate. Every SUS440A plate shipped by SHH STEEL carries an inspection document to JIS G 0415, type 3.1 by default. Purchase orders should name JIS G4305, its edition, the grade, the thickness and the inspection document required, so the certificate can be checked against the same tables. The figures quoted are the limits of JIS G4305; the actual values for a given heat are those reported on the mill test certificate.
- What is the chemical composition of JIS G4305 SUS440A?
- JIS G4305:2021 sets the following heat-analysis limits for SUS440A: Carbon (C) 0.60 – 0.75; Silicon (Si) ≤ 1.00; Manganese (Mn) ≤ 1.00; Phosphorus (P) ≤ 0.040; Sulphur (S) ≤ 0.030; Nickel (Ni) ≤ 0.60; Chromium (Cr) 16.00 – 18.00; Molybdenum (Mo) ≤ 0.75. The 0.60 – 0.75 % carbon is what gives SUS440A its high hardness after quenching. Elements not listed are not added intentionally; where the standard asks for the content of optional elements to be reported, it appears on the inspection certificate. SHH STEEL checks every certificate against these limits before shipment and can arrange an independent check analysis by a partner laboratory. If a drawing names more than one standard, the material must meet each of them, and the certificate should state every standard it claims.
- What are the mechanical properties of SUS440A plate?
- In the annealed condition, JIS G4305 Table 12 requires SUS440A to have a 0.2 % proof stress of at least 245 N/mm², a tensile strength of at least 590 N/mm² and an elongation of at least 15 %, with hardness not above 255 HBW or 25 HRC. After quenching and tempering, Table 13 requires at least 40 HRC on test pieces treated to the Annex JA conditions. The annealed values matter for machining and forming; the hardened value shows what the steel can reach. SHH STEEL checks the annealed results on the 3.1 certificate for every heat. Where a project specification adds requirements beyond JIS G4305, they should be written into the enquiry so the mill can confirm them before rolling.
- How is SUS440A heat treated?
- Annex JA of JIS G4305 gives annealing at 800 – 900 °C with slow cooling (or about 750 °C with rapid cooling), quenching from 1 010 – 1 070 °C and tempering at 150 – 400 °C as the example heat treatment for SUS440A. The annex is informative, so it shows typical conditions rather than mandatory limits, and the mill applies its own qualified practice within the requirements of the standard. Users normally harden the parts after machining. SHH STEEL supplies SUS440A in the heat-treated condition stated on the order and asks the mill to record the treatment on the inspection certificate, so the fabricator knows the starting condition of the material. Any supplementary test, such as a product analysis or a corrosion test, has to be agreed at the enquiry stage because it cannot be added after delivery.
- What sizes and finishes of SUS440A can SHH STEEL supply?
- JIS G4305 lists standard plate thicknesses from 0.30 mm to 20.0 mm and sheet sizes from 1 000 × 2 000 mm to 1 524 × 3 048 mm; strip is listed from 0.30 mm to 6.0 mm. The standard finishes are No.2D, No.2B, BA and HL, with polished finishes made by the manufacturer's method. Other sizes are possible by agreement, and hot-rolled plate is ordered to JIS G 4304. SHH STEEL confirms with the mill which sizes it can roll in SUS440A, then offers cut-to-size blanks, slit coil or full plates. Lead time is normally 30 – 40 days. Any supplementary test, such as a product analysis or a corrosion test, has to be agreed at the enquiry stage because it cannot be added after delivery.
- Is SUS440A harder than SUS420J2?
- According to JSSA, yes: SUS440A reaches a higher quenched hardness than SUS420J2 and also has better corrosion resistance. The reason is its higher carbon (0.60 – 0.75 %) and higher chromium (16.00 – 18.00 %). In JIS G4305 Table 13, SUS440A requires at least 40 HRC after quenching and tempering. The higher carbon also makes it less easy to weld and form, so it is used for wear parts such as bearings, valves and blades rather than for welded structures. SHH STEEL can help a buyer compare the two grades for a given part. The figures quoted are the limits of JIS G4305; the actual values for a given heat are those reported on the mill test certificate. If a drawing names more than one standard, the material must meet each of them, and the certificate should state every standard it claims.
Conclusion
JIS G4305 SUS440A Steel Plate (440A stainless steel) is the high-carbon 17 % chromium martensitic grade of JIS G4305, supplied annealed and hardened by the user to at least 40 HRC for bearings, valves and blades. SHH STEEL supplies it with full JIS G4305 compliance, 3.1 inspection certificates and optional third-party testing, with a normal lead time of 30 – 40 days. Contact SHH STEEL for availability, sizes and a quotation for your SUS440A requirement.
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