---
title: "SCM430 Forgings (JIS G4053 Chromium-Molybdenum Steel)"
url: https://www.steelforgepieces.com/Alloy-Steel/SCM430.html
publisher: Jiangyin Jiangnan Metal Co., Ltd.
updated: 2026-09-15
---

# SCM430 Forgings (JIS G4053 Chromium-Molybdenum Steel)

Seamless rolled rings, shafts, flanges, discs, sleeves and bars in SCM430, open-die forged to your drawing and supplied annealed, normalized or quenched and tempered, with an EN 10204 3.1 or 3.2 certificate.

**SCM430 is a chromium-molybdenum low-alloy steel for machine structural use, specified in the Japanese standard JIS G4053 (formerly JIS G4105), with 0.28–0.33% carbon, 0.60–0.90% manganese, 0.90–1.20% chromium and 0.15–0.30% molybdenum.** It is used quenched and tempered. For a 25 mm test piece, JIS G4053 gives a tensile strength of at least 830 MPa, a yield point of at least 685 MPa, at least 18% elongation and a hardness of 241–302 HBW. Its lower carbon makes it tougher and easier to weld than SCM435 or SCM440, with less strength and hardenability. AISI 4130, EN 25CrMo4 (1.7218) and GB 30CrMo are the nearest equivalents, but none of them matches SCM430 exactly.

We are **Jiangyin Jiangnan Metal Co., Ltd.**, an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge SCM430 to customer drawings as seamless rolled rings, shafts, flanges, discs, sleeves, blocks and round bars. The steel is melted by EAF + LF + VD, and every part is heat treated, ultrasonically tested and certified to EN 10204 3.1 or 3.2. For a quotation, send your drawing to [sales@steelforgepieces.com](mailto:sales@steelforgepieces.com?subject=RFQ%20SCM430%20forgings) or call [+86 189 2135 9659](tel:+8618921359659).

## SCM430 key data

| Item | Value |
|---|---|
| Grade | SCM430 (also written SCM 430) |
| Standard | JIS G4053, which replaced JIS G4105 in 2003 |
| Steel type | Medium-carbon Cr-Mo low-alloy steel, heat treatable |
| Nearest equivalents | AISI 4130 (UNS G41300), EN 25CrMo4 (1.7218), GB 30CrMo |
| Tensile strength, quenched and tempered | ≥ 830 MPa (120.4 ksi) |
| Yield point, quenched and tempered | ≥ 685 MPa (99.4 ksi) |
| Hardness, quenched and tempered | 241–302 HBW (≈ 23–32 HRC) |
| Hardening | 830–880 °C, oil quench |
| Tempering | 530–630 °C, rapid cooling |
| Density | 7.85 g/cm³ (0.284 lb/in³) |
| Delivery conditions | Annealed, normalized, or quenched and tempered |
| Steelmaking route | EAF + LF + VD |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 |
| Certificate | EN 10204 3.1; 3.2 third-party witnessed on request |
| Manufacturer | Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, China |

Published by Jiangyin Jiangnan Metal Co., Ltd. Technical data checked against JIS G4053, ASTM A29/A29M, EN 10083-3 and GB/T 3077. Last updated 15 September 2026.

## SCM430 overview and when to use it

The grade name follows the JIS G4053 system. S stands for steel, C for chromium and M for molybdenum. The digit 4 is the code for the main alloy content, and 30 is the nominal carbon content in hundredths of a percent. SCM430 is therefore the 0.30% carbon member of the SCM4xx series, which runs from SCM415 to SCM445.

Chromium and molybdenum raise hardenability, so SCM430 hardens more deeply on quenching than a plain carbon steel with the same carbon content. Molybdenum also reduces susceptibility to temper embrittlement and slows softening during tempering. Holding carbon at 0.28–0.33% gives SCM430 higher toughness, a lower carbon equivalent and better weldability than SCM435 and SCM440, which are chosen when more strength or hardness is needed.

SCM430 has medium hardenability, so a heavy forging will not reach the JIS test-piece values at its center. See [properties of SCM430 in large forgings](https://www.steelforgepieces.com/Alloy-Steel/SCM430.html#large-sections).

### Specify SCM430 when

- The part needs a quenched-and-tempered tensile strength of about 830 MPa together with good impact toughness.
- The part will be welded, weld repaired or clad, and SCM435 or SCM440 would need more demanding preheat.
- The ruling section is moderate enough for an oil quench to harden it through, or lower properties at the core are acceptable.
- The drawing calls for a JIS grade, or allows a 4130-type chromium-molybdenum steel.

### Specify another grade when

- Higher strength or hardness is needed in the same section. Use SCM435, [SCM440](https://www.steelforgepieces.com/Alloy-Steel/SCM440.html) or [42CrMo4](https://www.steelforgepieces.com/Alloy-Steel/42CrMo4.html).
- A large section must reach full strength at the core. Use a nickel-chromium-molybdenum steel such as 34CrNiMo6 or AISI 4340.
- The part is a code-stamped pressure component. Order it to the forging specification listed in the design code, not to SCM430.
- Sustained load at elevated temperature governs the design. Use a creep-resistant chromium-molybdenum grade such as ASTM A182 F11 or F22.

## Chemical composition of SCM430

The limits below are the SCM430 ranges in JIS G4053, heat (ladle) analysis, in weight percent, with iron as the balance. Carbon content is the only composition difference between SCM430, SCM435 and SCM440.

**Table 1. SCM430 chemical composition limits to JIS G4053, weight %**

| Element | Min % | Max % | Role in SCM430 |
|---|---|---|---|
| Carbon (C) | 0.28 | 0.33 | Sets quenched-and-tempered strength. SCM435 is 0.33–0.38 and SCM440 is 0.38–0.43 |
| Silicon (Si) | 0.15 | 0.35 | Deoxidizer; adds some solid-solution strength |
| Manganese (Mn) | 0.60 | 0.90 | Adds hardenability and strength; combines with sulfur |
| Phosphorus (P) | — | 0.030 | Impurity; held low to protect toughness |
| Sulfur (S) | — | 0.030 | Impurity; held low to limit sulfide inclusions |
| Chromium (Cr) | 0.90 | 1.20 | Main hardenability element; resists softening in tempering |
| Molybdenum (Mo) | 0.15 | 0.30 | Adds hardenability; reduces temper embrittlement |
| Nickel (Ni) | — | 0.25 | Residual element, not an intentional addition |
| Copper (Cu) | — | 0.30 | Residual element |

Every certificate reports the heat analysis. Product analysis on the finished forging is available on request. If you need phosphorus, sulfur or residual elements below the JIS limits, state the limits on the enquiry.

### Carbon equivalent of SCM430

Using the IIW formula CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, the carbon equivalent of SCM430 is 0.59 at the minimum JIS limits, about 0.69 at mid-range chemistry with no residual nickel or copper, and 0.82 at the maximum limits including residuals. At that level the heat-affected zone hardens as it cools, so welding forging-sized SCM430 sections needs preheat, low-hydrogen consumables and post-weld heat treatment.

## Mechanical properties of SCM430

JIS G4053 gives the following properties for SCM430 after quenching from 830–880 °C in oil and tempering at 530–630 °C with rapid cooling, measured on a 25 mm test piece.

**Table 2. SCM430 mechanical properties, quenched and tempered, 25 mm test piece (JIS G4053)**

| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | ≥ 830 MPa | ≥ 120,400 psi |
| Yield point (yield strength) | ≥ 685 MPa | ≥ 99,400 psi |
| Elongation | ≥ 18% | ≥ 18% |
| Reduction of area | ≥ 55% | ≥ 55% |
| Charpy impact value, U-notch | ≥ 108 J/cm² | — |
| Brinell hardness | 241–302 HBW | ≈ 23–32 HRC |

The JIS impact value is absorbed energy per unit area on a U-notch test piece and cannot be converted directly to Charpy V-notch joules. If the design needs KV values at a stated temperature, put them on the order.

### Properties of SCM430 in large forgings

The values in Table 2 are for a 25 mm test piece, not for a finished forging. In a thick section the core cools more slowly during quenching, so strength and hardness at the center are lower, and impact toughness is usually lower than in fully hardened material. For each SCM430 forging we agree the acceptance values, the test-piece location (for example 1/4 thickness or 1/3 radius) and the test direction with the buyer before production, and we report the results on the EN 10204 3.1 certificate.

## Heat treatment of SCM430

SCM430 forgings are delivered in one of three conditions. Annealed material is soft for machining. Normalized material has a refined, uniform grain structure. Quenched and tempered material has the JIS strength and is the usual service condition. The tempering temperature is set within the range to meet the hardness or strength on the order.

**Table 3. SCM430 forging and heat treatment temperatures**

| Process | Temperature | Cooling | Purpose |
|---|---|---|---|
| Hot forging | 1,200 °C to 950 °C | Slow cooling after forging | Shapes the part and breaks down the cast structure; reheat rather than forge below 950 °C |
| Normalizing | 870–900 °C | Still air | Refines grain after forging and gives a uniform structure before hardening or machining |
| Annealing | 830–860 °C | Slow furnace cooling | Softens the steel and relieves forging stress for machining |
| Hardening | 830–880 °C | Oil quench | Transforms the structure to martensite and bainite, depending on section size |
| Tempering | 530–630 °C | Rapid cooling in water or oil | Sets the final strength, hardness and toughness |
| Stress relieving | Below the final tempering temperature | Slow cooling | Relieves machining or welding stress without lowering strength |

Hardening and tempering ranges are those given in JIS G4053. Forging, normalizing, annealing and stress-relieving temperatures are typical practice for 4130-type chromium-molybdenum steel and are fixed for each order in the heat treatment procedure.

### Sour (H₂S) service and the JIS hardness range

NACE MR0175 / ISO 15156-2 limits low-alloy steels such as SCM430 to a maximum hardness of 22 HRC (about 237 HBW) for sulfide stress cracking resistance. That limit is below the 241–302 HBW range JIS G4053 gives for quenched-and-tempered SCM430, so sour-service forgings are tempered at a higher temperature, usually at or above the top of the JIS range, and reach lower strength. State the NACE requirement on the order.

## Physical properties of SCM430

**Table 4. Nominal physical properties of SCM430, room temperature unless noted**

| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting point | ≈ 1,432 °C | ≈ 2,610 °F |
| Modulus of elasticity | 190–210 GPa | 27,600–30,500 ksi |
| Shear modulus | ≈ 80 GPa | ≈ 11,600 ksi |
| Poisson's ratio | 0.27–0.30 | 0.27–0.30 |
| Thermal conductivity at 100 °C | 42.7 W/(m·K) | 296 BTU·in/(h·ft²·°F) |
| Mean thermal expansion, 20–100 °C | 11–12 × 10⁻⁶ /K | 6.1–6.7 × 10⁻⁶ /°F |
| Magnetic behavior | Ferromagnetic | Ferromagnetic |

Nominal values for 4130-type chromium-molybdenum steel compiled from published data, for design screening only. Because SCM430 is ferromagnetic, forgings can be surface-inspected by magnetic particle testing. If a physical property is used in a design calculation, ask for the value at the design temperature in writing.

## SCM430 equivalent grades

SCM430 is often listed as equivalent to AISI 4130, EN 25CrMo4 and GB 30CrMo. Table 5 compares their composition ranges.

**Table 5. SCM430 compared with its international equivalents, weight %**

| Grade | Standard | C | Mn | Cr | Mo | Difference from SCM430 |
|---|---|---|---|---|---|---|
| SCM430 | JIS G4053 | 0.28–0.33 | 0.60–0.90 | 0.90–1.20 | 0.15–0.30 | Reference grade |
| AISI 4130 | UNS G41300; ASTM A29/A29M, SAE J404 | 0.28–0.33 | 0.40–0.60 | 0.80–1.10 | 0.15–0.25 | Same carbon; lower manganese, chromium and molybdenum limits |
| 25CrMo4 (1.7218) | EN 10083-3 | 0.22–0.29 | 0.60–0.90 | 0.90–1.20 | 0.15–0.30 | Same alloy ranges; lower carbon |
| 34CrMo4 (1.7220) | EN 10083-3 | 0.30–0.37 | 0.60–0.90 | 0.90–1.20 | 0.15–0.30 | Same alloy ranges; higher carbon, closer to SCM435 |
| 30CrMo | GB/T 3077 | 0.26–0.33 | 0.40–0.70 | 0.80–1.10 | 0.15–0.25 | Similar carbon; lower manganese, chromium and molybdenum limits |

None of them is an exact match, and the differences show up when a mill certificate is checked against the drawing. AISI 4130 shares the carbon range, but its manganese range of 0.40–0.60% meets the SCM430 range of 0.60–0.90% at a single value. 25CrMo4 shares every alloy range but caps carbon at 0.29%. 34CrMo4 matches SCM430 exactly between 0.30% and 0.33% carbon. GB 30CrMo covers the whole SCM430 carbon range but has lower manganese, chromium and molybdenum ceilings.

### Dual certification with SCM430

One heat can carry two grade names only where the composition ranges overlap. Table 6 shows the overlap for each pair, worked out from the heat-analysis limits.

**Table 6. Chemistry windows for dual certification with SCM430, weight %**

| Dual certification | C | Mn | Cr | Mo | Practical |
|---|---|---|---|---|---|
| SCM430 + 34CrMo4 | 0.30–0.33 | 0.60–0.90 | 0.90–1.20 | 0.15–0.30 | Yes |
| SCM430 + 30CrMo | 0.28–0.33 | 0.60–0.70 | 0.90–1.10 | 0.15–0.25 | Yes |
| SCM430 + 25CrMo4 | 0.28–0.29 | 0.60–0.90 | 0.90–1.20 | 0.15–0.30 | Yes, with tight carbon control |
| SCM430 + AISI 4130 | 0.28–0.33 | 0.60 only | 0.90–1.10 | 0.15–0.25 | No; manganese would have to be exactly 0.60% |

Phosphorus, sulfur and silicon must also meet the stricter limit of the two standards; for the EN grades this means phosphorus of 0.025% maximum.

When a drawing specifies SCM430 and the buyer also accepts an EN or GB grade, we can melt the heat inside the overlap and list both designations on one EN 10204 3.1 certificate. Dual certification with AISI 4130 is not practical, so order to one standard and agree any deviation in writing.

## SCM430 vs SCM435 vs SCM440

The three grades have the same manganese, chromium and molybdenum ranges and differ only in carbon. More carbon gives higher strength and hardness, but lower toughness and weldability.

**Table 7. SCM430, SCM435 and SCM440 compared, quenched and tempered, 25 mm test piece (JIS G4053)**

| Property | SCM430 | SCM435 | SCM440 |
|---|---|---|---|
| Carbon, % | 0.28–0.33 | 0.33–0.38 | 0.38–0.43 |
| Tensile strength, min | 830 MPa | 930 MPa | 980 MPa |
| Yield point, min | 685 MPa | 785 MPa | 835 MPa |
| Elongation, min | 18% | 15% | 12% |
| Reduction of area, min | 55% | 50% | 45% |
| Charpy U-notch, min | 108 J/cm² | 78 J/cm² | 59 J/cm² |
| Hardness | 241–302 HBW | 269–331 HBW | 285–352 HBW |
| Carbon equivalent (IIW, mid-range) | ≈ 0.69 | ≈ 0.74 | ≈ 0.79 |
| Choose it for | Toughness and weldability | Balance of strength and toughness | Highest strength and hardness |

Carbon equivalents are calculated at mid-range chemistry with no residual nickel or copper. See also [SCM440 forgings](https://www.steelforgepieces.com/Alloy-Steel/SCM440.html).

## SCM430 forgings we produce

As an open-die forging plant, we make every SCM430 part to the customer's drawing or sketch. There is no fixed catalog and no tooling charge, and single pieces can be ordered.

- **Seamless rolled rings.** Pierced and ring-rolled with no weld seam, in rectangular or profiled sections for gear rims, bearing housings and flange blanks. See [seamless rolled rings](https://www.steelforgepieces.com/Seamless-Rolled-Rings/Seamless-Rolled-Ring.html).
- **Forged flanges.** Weld neck, slip-on, blind and custom flanges, with dimensions to ASME B16.5 or B16.47 or to your drawing.
- **Shafts and spindles.** Straight, stepped and eccentric shafts for pumps, compressors, gearboxes and hydraulic equipment.
- **Discs and gear blanks.** Upset-forged discs for gears, couplings, covers and blind ends. See [forged disks](https://www.steelforgepieces.com/Forging-Disks/).
- **Sleeves and bushings.** Hollow forged, trepanned or bored, thin or heavy wall. See [forging sleeves](https://www.steelforgepieces.com/Forging-Sleeves/).
- **Valve bodies, bonnets and stems.** Forged blanks for ball, gate, globe, check and plug valves. See [forged valve stems](https://www.steelforgepieces.com/Forged-Valve-Parts/Forged-Valve-Stem.html).
- **Cylinders and hydraulic parts.** Cylinder bodies, heads, end caps and manifold blocks. See [forged cylinders](https://www.steelforgepieces.com/Forged-Cylinders/Forged-Cylinder.html).
- **Round bars, blocks and hollow bars.** Forged and peeled or rough turned, and cut to length.

**Table 8. Open-die forging capability for carbon and alloy steels**

| Item | Capability |
|---|---|
| Outside diameter (rings, discs) | 80–6,000 mm |
| Length (shafts, bars) | Up to 12,000 mm |
| Single-piece weight | 10–15,000 kg |
| Forging equipment | 1 t, 3 t, 5 t and 9 t open-die hammers; 5,000 t hydraulic press |
| Ring rolling | 3 m and 6 m seamless ring rolling mills |
| Machining allowance | Normally 6–20 mm per surface, or finish machined to drawing |

For SCM430, the practical size of a quenched-and-tempered part is also limited by the section that has to meet the required properties. Heavy sections are quoted with property values agreed at the test location.

## How SCM430 forgings are made

1. **Steelmaking.** Electric arc furnace melting, ladle furnace refining and vacuum degassing (EAF + LF + VD). Vacuum degassing lowers the hydrogen content, which protects heavy chromium-molybdenum forgings from hydrogen flaking.
2. **Material check.** Heat chemistry is confirmed by spectrometer against the SCM430 limits before the ingot or billet is heated.
3. **Open-die forging and ring rolling.** The stock is forged between 1,200 °C and 950 °C on hammers or the 5,000 t press with a controlled reduction ratio. Rings are pierced and rolled seamless on the ring mills.
4. **Cooling and preliminary heat treatment.** Slow cooling after forging, then normalizing or annealing to refine the grain and prepare the part for machining.
5. **Rough machining.** Parts are rough machined before hardening, so the quench acts on a section close to final size and ultrasonic testing can be done on clean surfaces.
6. **Quenching and tempering.** Oil quenching from 830–880 °C and tempering at 530–630 °C, or the delivery condition on the order.
7. **Testing.** Tensile, impact and hardness tests at the agreed location, ultrasonic testing, magnetic particle testing and dimensional inspection.
8. **Certification and dispatch.** EN 10204 3.1 certificate as standard, or 3.2 with a third-party inspector. Parts are marked, preserved and packed for sea or air freight.

## Applications of SCM430 forgings

**Table 9. Typical SCM430 forged components by industry**

| Industry | SCM430 forged components |
|---|---|
| Oil and gas | Valve bodies, bonnets and stems; wellhead and christmas-tree components; flanges and hubs where a 4130-type chromium-molybdenum steel is specified |
| Pumps and compressors | Plunger-pump and compressor shafts, sleeves and couplings |
| Hydraulics | Cylinder heads, end caps, glands and manifold blocks |
| Power transmission | Shafts, gear blanks, hubs and couplings for moderately loaded drives |
| Mining and construction machinery | Pins, bushings, sleeves and rings, including parts that may later be weld repaired |
| General heavy machinery | Spindles, rings, discs and blocks machined into structural components |

## Welding and machining SCM430

### Welding

- Use low-hydrogen processes and consumables matched to the strength required.
- Preheat and hold the interpass temperature, typically in the 150–300 °C range, rising with section thickness and restraint. The welding procedure specification sets the exact values.
- Post-weld heat treat below the final tempering temperature, or re-quench and temper the whole part when full properties are needed across the weld.
- Weld repair of a quenched-and-tempered forging needs a qualified procedure and the buyer's approval.

### Machining

- Annealed or normalized SCM430 machines readily. 4130-type steel is rated at about 70% of AISI 1212 in the annealed and cold-drawn condition.
- Rough machine before quenching and tempering, then finish machine after heat treatment.
- Near the top of the quenched-and-tempered range, around 30 HRC, use carbide tooling and rigid setups.

## Testing, inspection and certification

- **Chemical analysis.** Heat analysis on every certificate; product analysis on the forging on request.
- **Mechanical testing.** Tensile strength, yield point, elongation and reduction of area; Charpy impact with U or V notch at the temperature ordered; Brinell hardness.
- **Metallography.** Grain size to ASTM E112 and non-metallic inclusions to ASTM E45 on request.
- **Ultrasonic testing.** EN 10228-3, SEP 1921 or ASTM A388, to the acceptance class on the order.
- **Magnetic particle testing.** EN 10228-1 or ASTM A275.
- **Dimensional inspection.** Checked against the drawing and recorded on the certificate.
- **Certification.** EN 10204 3.1 as standard; EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request, with heat-number traceability and hard stamping.

## Frequently asked questions about SCM430

### What is SCM430 steel?

SCM430 is a Japanese chromium-molybdenum low-alloy steel for machine structural use, specified in JIS G4053 (formerly JIS G4105). It contains 0.28–0.33% carbon, 0.60–0.90% manganese, 0.90–1.20% chromium and 0.15–0.30% molybdenum, and is used quenched and tempered for shafts, rings, flanges, valve parts and other forgings that need strength, toughness and moderate weldability.

### Is SCM430 the same as AISI 4130?

No, but it is close. Both grades have 0.28–0.33% carbon. SCM430 allows 0.60–0.90% manganese and 0.90–1.20% chromium, while AISI 4130 allows 0.40–0.60% manganese and 0.80–1.10% chromium, and its molybdenum ceiling is 0.25% against 0.30% for SCM430. The two manganese ranges meet only at 0.60%, so one heat cannot practically be certified to both. Order to one standard and agree any substitution in writing.

### What is the equivalent of SCM430 in European and Chinese standards?

The nearest European grade is 25CrMo4 (1.7218) to EN 10083-3, which has the same manganese, chromium and molybdenum ranges as SCM430 but 0.22–0.29% carbon. 34CrMo4 (1.7220) overlaps SCM430 at 0.30–0.33% carbon. The nearest Chinese grade is 30CrMo to GB/T 3077, with 0.26–0.33% carbon and lower manganese and chromium ranges.

### What is the difference between SCM430, SCM435 and SCM440?

The difference is carbon: 0.28–0.33% for SCM430, 0.33–0.38% for SCM435 and 0.38–0.43% for SCM440, with the same manganese, chromium and molybdenum ranges. After quenching and tempering, JIS G4053 gives minimum tensile strengths of 830, 930 and 980 MPa respectively. SCM430 is the toughest and most weldable of the three; SCM440 is the strongest and hardest.

### What are the mechanical properties and hardness of SCM430?

Quenched from 830–880 °C in oil and tempered at 530–630 °C, SCM430 has a minimum tensile strength of 830 MPa, a minimum yield point of 685 MPa, at least 18% elongation, at least 55% reduction of area, a Charpy U-notch value of at least 108 J/cm² and a hardness of 241–302 HBW (about 23–32 HRC). These JIS values are for a 25 mm test piece; large forgings reach lower values at the core.

### How is SCM430 heat treated?

SCM430 is hardened by heating to 830–880 °C and quenching in oil, then tempered at 530–630 °C and cooled rapidly. Forgings are normally normalized at 870–900 °C or annealed at 830–860 °C first, to refine the grain and allow rough machining. The tempering temperature is chosen within the range to meet the hardness or strength on the order.

### Can SCM430 be welded?

Yes, with precautions. The IIW carbon equivalent of SCM430 is about 0.69 at mid-range chemistry, so the heat-affected zone hardens as it cools. For forging-sized sections, use low-hydrogen consumables, preheat and interpass temperatures typically in the 150–300 °C range, and post-weld heat treatment below the final tempering temperature, all under a qualified welding procedure.

### Which standard covers SCM430: JIS G4105 or JIS G4053?

JIS G4053. SCM430 was originally specified in JIS G4105, the Japanese standard for chromium-molybdenum steels. In 2003 JIS G4105 was consolidated with the other low-alloy machine structural steel standards into JIS G4053, which is the current standard. Certificates that still cite JIS G4105 refer to the same grade, but new orders should cite JIS G4053.

### Can SCM430 forgings be used in sour (H₂S) service?

Yes, if they meet NACE MR0175 / ISO 15156-2. That standard limits low-alloy steels such as SCM430 to a maximum hardness of 22 HRC (about 237 HBW), which is below the 241–302 HBW range JIS gives for quenched-and-tempered SCM430. Sour-service forgings are therefore tempered at a higher temperature, with lower strength, and the NACE requirement must be stated on the order.

### What sizes of SCM430 forgings can you supply?

We forge carbon and alloy steels, including SCM430, in outside diameters from 80 mm to 6,000 mm, lengths up to 12,000 mm and single-piece weights from 10 kg to 15,000 kg. Our plant has 1 t, 3 t, 5 t and 9 t open-die hammers, a 5,000 t hydraulic press and 3 m and 6 m ring rolling mills. Single pieces can be ordered and there is no tooling charge. The properties a part can reach depend on its section size, so please send the drawing together with the property requirements.

### What certificate comes with SCM430 forgings?

Every SCM430 forging we ship has an EN 10204 3.1 inspection certificate with the heat number, chemical analysis, heat treatment, mechanical test results, ultrasonic test results and dimensions. EN 10204 3.2 certification witnessed by TÜV, BV, LR, SGS or DNV is available if requested when the order is placed.

### Where are your SCM430 forgings made?

All our SCM430 forgings are made at the Jiangyin Jiangnan Metal Co., Ltd. plant at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The same plant forges other alloy steels, carbon steels, tool steels, stainless steels and nickel alloys, and we export worldwide. Contact [sales@steelforgepieces.com](mailto:sales@steelforgepieces.com) or [+86 189 2135 9659](tel:+8618921359659).

## Request a quotation for SCM430 forgings

Send a drawing, a sketch, or just the dimensions and quantity. Please include, where available, the grade and standard (SCM430 to JIS G4053, or an accepted alternative), product form, dimensions and machining allowance, quantity, delivery condition, mechanical requirements with the test location, ultrasonic testing standard and class, certificate type (EN 10204 3.1 or 3.2) and the required delivery date.

- **Company:** Jiangyin Jiangnan Metal Co., Ltd.
- **Business:** Open-die forging factory
- **Address:** No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- **Telephone / WhatsApp:** [+86 189 2135 9659](tel:+8618921359659)
- **Email:** [sales@steelforgepieces.com](mailto:sales@steelforgepieces.com?subject=RFQ%20SCM430%20forgings)
- **Website:** [www.steelforgepieces.com](https://www.steelforgepieces.com/)

## Summary

SCM430 (JIS G4053, formerly JIS G4105) is a medium-carbon chromium-molybdenum steel with 0.28–0.33% C, 0.15–0.35% Si, 0.60–0.90% Mn, 0.90–1.20% Cr and 0.15–0.30% Mo, with P and S 0.030% max, Ni 0.25% max and Cu 0.30% max. After oil quenching from 830–880 °C and tempering at 530–630 °C, a 25 mm test piece has at least 830 MPa tensile strength, 685 MPa yield point, 18% elongation and 55% reduction of area, with a hardness of 241–302 HBW. The closest equivalents are AISI 4130, EN 25CrMo4 (1.7218) and GB 30CrMo, but none is identical. Jiangyin Jiangnan Metal Co., Ltd. in Jiangyin, China forges SCM430 rolled rings, shafts, flanges, discs, sleeves and bars up to 6,000 mm in diameter and 15,000 kg, with ultrasonic testing and EN 10204 3.1 or 3.2 certificates.

## Standards referenced on this page

- **JIS G4053**: low-alloyed steels for machine structural use (SCM430, SCM435, SCM440)
- **JIS G4105**: former Japanese standard for chromium-molybdenum steels, replaced by JIS G4053
- **ASTM A29/A29M and SAE J404**: chemical composition of AISI/SAE 4130
- **EN 10083-3**: alloy steels for quenching and tempering (25CrMo4, 34CrMo4)
- **GB/T 3077**: Chinese alloy structural steels (30CrMo)
- **NACE MR0175 / ISO 15156-2**: materials for H₂S-containing environments in oil and gas production
- **EN 10228-1 and EN 10228-3**: magnetic particle and ultrasonic testing of steel forgings
- **ASTM A388/A388M and ASTM A275/A275M**: ultrasonic and magnetic particle examination of steel forgings
- **SEP 1921**: Stahl-Eisen-Prüfblatt ultrasonic test method with acceptance classes such as C/c, D/d and E/e
- **EN 10204**: types of inspection documents for metallic products (3.1 and 3.2)

## Related grades and product forms

### Chromium-molybdenum steels we forge

- [AISI 4130 forgings](https://www.steelforgepieces.com/Alloy-Steel/AISI-4130.html)
- [34CrMo4 forgings](https://www.steelforgepieces.com/Alloy-Steel/34CrMo4.html)
- [1.7220 forgings](https://www.steelforgepieces.com/Alloy-Steel/1.7220.html)
- [AISI 4135 forgings](https://www.steelforgepieces.com/Alloy-Steel/AISI-4135.html)
- [SCM440 forgings](https://www.steelforgepieces.com/Alloy-Steel/SCM440.html)
- [AISI 4140 forgings](https://www.steelforgepieces.com/Alloy-Steel/AISI-4140.html)
- [42CrMo4 forgings](https://www.steelforgepieces.com/Alloy-Steel/42CrMo4.html)
- [AISI 8630 forgings](https://www.steelforgepieces.com/Alloy-Steel/AISI-8630.html)

### By product form

- [Seamless rolled rings](https://www.steelforgepieces.com/Seamless-Rolled-Rings/Seamless-Rolled-Ring.html)
- [Forged rings](https://www.steelforgepieces.com/Forging-Rings/)
- [Forged disks](https://www.steelforgepieces.com/Forging-Disks/)
- [Forging sleeves](https://www.steelforgepieces.com/Forging-Sleeves/)
- [Forged parts](https://www.steelforgepieces.com/Forged-Parts/Forged-Part.html)
- [All products](https://www.steelforgepieces.com/Products/)

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© 2026 Jiangyin Jiangnan Metal Co., Ltd. All rights reserved. Technical data on this page is compiled from JIS G4053, ASTM A29/A29M, EN 10083-3, GB/T 3077 and published alloy steel literature, and is offered for guidance only. The inspection certificate supplied with each forging governs acceptance.