JIS G4305 SUS329J4L Steel Plate | 329J4L Stainless Steel
What is JIS G4305 SUS329J4L Steel Plate?
As a stainless steel supplier and China mill-direct exporter, SHH STEEL supplies JIS G4305 SUS329J4L Steel Plate, also known as 329J4L stainless steel. SUS329J4L is a super-duplex (austenitic-ferritic) grade of JIS G4305:2021, the Japanese Industrial Standard for cold-rolled stainless steel plate, sheet and strip. It is a low-carbon, nitrogen-alloyed duplex grade with 24.00 – 26.00 % chromium, 5.50 – 7.50 % nickel, 2.50 – 3.50 % molybdenum and 0.08 – 0.30 % nitrogen.
SUS329J4L sits above JIS G4305 SUS329J3L steel plate in chromium and nickel. GB/T 20878 cross-references it to UNS S31260 and to the Chinese grade 022Cr25Ni7Mo3N (ISC S22583), with EN 1.4481 shown in brackets as a related number. JSSA groups SUS329J3L and SUS329J4L together and rates them above JIS G4305 SUS329J1 for corrosion resistance, especially pitting resistance, and for strength.
This page summarises the requirements of JIS G4305:2021 for SUS329J4L: 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 SUS329J4L. SHH STEEL quotes either standard and confirms the edition named on the drawing before an order is placed.
SUS329J4L 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 | SUS329J4L (austenitic-ferritic (duplex)) | 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. Clause 7 makes intergranular corrosion testing a matter for agreement.
Chemical composition of JIS G4305 SUS329J4L (heat analysis, %)
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.030 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.50 |
| Phosphorus (P) | ≤ 0.040 |
| Sulphur (S) | ≤ 0.030 |
| Nickel (Ni) | 5.50 – 7.50 |
| Chromium (Cr) | 24.00 – 26.00 |
| Molybdenum (Mo) | 2.50 – 3.50 |
| Nitrogen (N) | 0.08 – 0.30 |
Using PREN = %Cr + 3.3 × %Mo + 16 × %N, the minimum limits give about 33.5. JSSA quotes a pitting index (Cr + 3.3 Mo) of 32.0 – 35.0 for the SUS329J3L/J4L group.
Mechanical properties of SUS329J4L in the solution-treated condition (JIS G4305 Table 10)
| Property | Requirement |
|---|---|
| 0.2 % proof stress | ≥ 450 N/mm² |
| Tensile strength | ≥ 620 N/mm² |
| Elongation | ≥ 18 % |
| Hardness | ≤ 302 HBW, or ≤ 32 HRC, or ≤ 320 HV |
These are the same minimums as for SUS329J3L, and about 2.5 times the 175 N/mm² proof stress of SUS316L in Table 8.
Surface finishes for SUS329J4L 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 duplex grades, No.2B and No.2D are the usual finishes for sheet and strip; HL and polished finishes are used where appearance matters.
Heat treatment and delivery condition of SUS329J4L
| Treatment | Condition (Annex JA, Table JA.2) |
|---|---|
| Solution treatment | 950 – 1 100 °C, rapid cooling |
Annex JA is informative. Rapid cooling after solution treatment keeps the austenite-ferrite structure free of the brittle intermetallic phases that can form in duplex steels held at intermediate temperatures, so SHH STEEL asks the mill to record the solution-treatment temperature on the certificate.
Table 19 of JIS G4305 gives a basic mass of 7.80 kg/(mm·m²) for SUS329J4L, which is used to calculate plate weight (equivalent to a density of 7.80 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 329J4L stainless steel
- Chromium 24 – 26 % with 2.50 – 3.50 % molybdenum and 0.08 – 0.30 % nitrogen.
- PREN about 33.5 at the minimum limits.
- Proof stress ≥ 450 N/mm², tensile strength ≥ 620 N/mm².
- Low carbon (≤ 0.030 %) for welded construction.
- Magnetic, like all duplex grades.
- Density 7.80 g/cm³ (JIS G4305 Table 19).
SUS329J4L equivalent grades
| System | Grade | Comment |
|---|---|---|
| ASTM / UNS | UNS S31260 (ASTM A240) | Close; A240 adds Cu 0.20 – 0.80 % and W 0.10 – 0.50 %, N 0.10 – 0.30 %, Mn ≤ 1.00 %, Si ≤ 0.75 % |
| China | 022Cr25Ni7Mo3N, ISC S22583 | Cross-referenced in GB/T 20878 Table C.1 |
| EN | (1.4481), shown in brackets in GB/T 20878 | Related; not a listed EN 10088-2 grade. Compare EN 10088-2 1.4410 plate |
Note that the IMOA duplex guide lists SUS 329J4L against S32750 (2507) in its cross-reference table; the JIS G4305 limits for SUS329J4L (Mo 2.50 – 3.50 %, N 0.08 – 0.30 %) do not match S32750 (Mo 3.0 – 5.0 %, N 0.24 – 0.32 %), whose JIS G4305:2021 counterpart is JIS G4305 SUS327L1. Because ASTM A240 S31260 requires copper and tungsten that JIS G4305 does not, dual certification is possible only for a heat that meets both. Where a drawing allows another super-duplex grade, ASTM A240 Type 2507 sheet and plate and ASTM A240 Type 2205 sheet and plate are commonly compared.
Applications of JIS G4305 SUS329J4L Steel Plate
The Japan Stainless Steel Association lists the main uses of the SUS329J3L/J4L group as:
- Water storage tanks (vapour-phase zone)
- Seawater heat exchangers
- Chemical equipment
- Oil-well tubes
- Water-pipe bridges
For lower alloy needs, JIS G4305 SUS329J3L steel plate is the usual alternative. SHH STEEL supplies both.
SUS329J4L compared with related JIS G4305 grades
The table compares SUS329J4L 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 SUS329J1 | 23.00 – 28.00 | 3.00 – 6.00 | 1.00 – 3.00 | no N range | 390 | 590 | 18 |
| JIS G4305 SUS329J3L | 21.00 – 24.00 | 4.50 – 6.50 | 2.50 – 3.50 | N 0.08 – 0.20 | 450 | 620 | 18 |
| SUS329J4L | 24.00 – 26.00 | 5.50 – 7.50 | 2.50 – 3.50 | N 0.08 – 0.30 | 450 | 620 | 18 |
| JIS G4305 SUS327L1 | 24.00 – 26.00 | 6.00 – 8.00 | 3.00 – 5.00 | N 0.24 – 0.32 | 550 | 795 | 15 |
| JIS G4305 SUS316L | 16.00 – 18.00 | 12.00 – 15.00 | 2.00 – 3.00 | C ≤ 0.030 | 175 | 480 | 40 |
SUS329J4L shares the strength of SUS329J3L but has more chromium (24 – 26 %) and nickel and a wider nitrogen range. SUS327L1 is the higher-molybdenum, 2507-type step up. SHH STEEL can quote the grades in this table side by side when a buyer is still choosing between them.
SUS329J4L to JIS G4305 (cold rolled) or JIS G4304 (hot rolled)?
SUS329J4L 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 SUS329J4L
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, SUS329J4L has a PREN of about 33.5 at the minimum of every range and about 42.3 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.
Duplex steels such as SUS329J4L combine chromium, molybdenum and nitrogen with a two-phase structure. The IMOA duplex guide reports that duplex grades resist chloride stress corrosion cracking much better than Type 304L and 316L in accelerated laboratory tests, which is one of the main reasons they are chosen for warm chloride service. The same guide warns that sigma phase can form between about 700 and 1 000 °C and that nitrides and carbides can form between 450 and 800 °C, so correct annealing and rapid cooling are essential to keep the corrosion resistance shown by PREN. JSSA quotes a pitting index of 32.0 – 35.0 for the SUS329J3L/J4L group.
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.
Physical properties of SUS329J4L
| Property | Typical value (IMOA duplex guide, S31260) |
|---|---|
| Density | 7.80 g/cm³ |
| Modulus of elasticity at 20 °C | 200 GPa |
| Specific heat at 20 °C | 502 J/(kg·K) |
JIS G4305 Table 19 gives a basic mass of 7.80 kg/(mm·m²) for SUS329J4L. The other values are typical producer data for S31260 quoted by the IMOA duplex guide and are for design guidance only. On request, SHH STEEL can pass on the producing mill’s own data sheet for the heat supplied.
Welding, forming and machining SUS329J4L
SUS329J4L is welded with the usual arc processes. The IMOA duplex guide notes that duplex weld metal resists hot cracking much better than austenitic weld metal, but that the procedure must let the heat-affected zone cool quickly to avoid intermetallic phases. As a general guideline it limits the interpass temperature to 150 °C for lean and standard duplex grades, and recommends that this limit be fixed when the procedure is qualified and monitored in production. Modern duplex grades are balanced to about 40 – 50 % ferrite, and the procedure should keep the weld and heat-affected zone close to this balance.
For joining duplex to duplex, the IMOA guide lists E2209 (standard duplex) or E2594 (super-duplex) filler metals. Because of 475 °C embrittlement of the ferrite, duplex steels should not be used for long periods above the temperatures allowed by the pressure-vessel design code; IMOA quotes 315 °C as the ASME limit for common duplex grades. In cold forming, duplex plate needs more force than 316L and shows more springback because of its higher proof stress, and its relative machinability is lower than that of austenitic grades, so tool settings should be adjusted.
SHH STEEL can deliver SUS329J4L cut to size, bevelled or pre-formed through its processing partners, so that the fabricator receives parts ready for welding.
- Qualify the procedure with an interpass limit and monitor it in production.
- Avoid long holds between 700 and 1 000 °C.
- Pickle and passivate after welding.
Dimensional tolerances for SUS329J4L 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 SUS329J4L 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 SUS329J4L
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 SUS329J4L plate and sheet
A complete enquiry avoids delays and wrong deliveries. For SUS329J4L we recommend stating:
- Standard and edition: JIS G 4305:2021 (cold rolled) or JIS G 4304:2021 (hot rolled), grade SUS329J4L.
- 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 SUS329J4L plate
Table 18 of JIS G4305 calculates plate mass from the basic mass in Table 19, which for SUS329J4L is 7.80 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 |
|---|---|---|
| SUS329J4L, 3.0 × 1 219 × 2 438 mm | 7.80 × 3.0 × (1.219 × 2.438) | about 69.5 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 SUS329J4L
As a SUS329J4L 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 duplex grade | SUS329J3L is supplied against a SUS329J4L order. | Chromium, nickel and nitrogen are checked against Table 4 and by PMI. |
| Phase balance | Slow cooling harms toughness and corrosion resistance. | Solution treatment and rapid cooling are recorded on the certificate. |
| Dual certification | A heat lacks the Cu and W that A240 S31260 requires. | Both sets of limits are checked before the order. |
| 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 SUS329J4L equivalent to?
- GB/T 20878 Table C.1 cross-references SUS329J4L to UNS S31260 and to the Chinese grade 022Cr25Ni7Mo3N, ISC S22583, with EN 1.4481 shown in brackets as a related number. The match with S31260 is close but not exact: ASTM A240 adds copper (0.20 – 0.80 %) and tungsten (0.10 – 0.50 %), sets nitrogen at 0.10 – 0.30 % and limits manganese to 1.00 % and silicon to 0.75 %. EN 10088-2 has no listed equivalent, though 1.4410 is often compared. SHH STEEL compares the limits for each order. Every SUS329J4L 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.
- What is the chemical composition of JIS G4305 SUS329J4L?
- JIS G4305:2021 sets the following heat-analysis limits for SUS329J4L: Carbon (C) ≤ 0.030; Silicon (Si) ≤ 1.00; Manganese (Mn) ≤ 1.50; Phosphorus (P) ≤ 0.040; Sulphur (S) ≤ 0.030; Nickel (Ni) 5.50 – 7.50; Chromium (Cr) 24.00 – 26.00; Molybdenum (Mo) 2.50 – 3.50; Nitrogen (N) 0.08 – 0.30. Nitrogen of 0.08 – 0.30 % is what makes the grade strong and resistant to pitting. 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. Where a project specification adds requirements beyond JIS G4305, they should be written into the enquiry so the mill can confirm them before rolling.
- What are the mechanical properties of SUS329J4L plate?
- In the solution-treated condition, JIS G4305 Table 10 requires SUS329J4L to have a 0.2 % proof stress of at least 450 N/mm², a tensile strength of at least 620 N/mm² and an elongation of at least 18 %. Hardness must not exceed 302 HBW, 32 HRC or 320 HV; only one hardness method is needed, chosen by the manufacturer unless the order specifies it. These values apply to thickness 0.30 mm and above, and proof stress applies when the purchaser asks for it. These are the same minimums as SUS329J3L. SHH STEEL checks the tensile and hardness results on the 3.1 inspection certificate for every heat before the material is released. 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.
- How is SUS329J4L heat treated?
- Annex JA of JIS G4305 gives solution treatment at 950 – 1 100 °C with rapid cooling as the example heat treatment for SUS329J4L. 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. Rapid cooling matters because duplex steels held at intermediate temperatures can form brittle phases. SHH STEEL supplies SUS329J4L 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. 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 sizes and finishes of SUS329J4L 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 SUS329J4L, then offers cut-to-size blanks, slit coil or full plates. Lead time is normally 30 – 40 days. The figures quoted are the limits of JIS G4305; the actual values for a given heat are those reported on the mill test certificate.
- Is SUS329J4L magnetic?
- Yes. SUS329J4L is a duplex (austenitic-ferritic) stainless steel, and the ferrite in its two-phase structure makes it magnetic, unlike the solution-treated 300-series austenitic grades. The magnetic response does not indicate a defect or a wrong grade; it is normal for duplex steel. For this reason a magnet cannot be used to tell SUS329J4L from ferritic or martensitic steels, and grade checks should rely on the certificate and positive material identification (PMI). Its higher chromium and nickel compared with SUS329J3L do not change this behaviour. Magnetic response can also vary slightly with the ferrite content, which depends on chemistry and heat treatment. SHH STEEL carries out PMI on request before shipment. 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.
Conclusion
JIS G4305 SUS329J4L Steel Plate (329J4L stainless steel) is a 25 % chromium, nitrogen-alloyed duplex grade with 450 N/mm² minimum proof stress and a PREN of about 33.5, used for seawater heat exchangers and chemical equipment. 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 SUS329J4L requirement.
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