What Is 4Cr5MoSiV1 Steel? GB Grade, Properties and Uses
4Cr5MoSiV1 is a Chinese GB hot-work tool steel commonly selected for dies, molds, and tooling exposed to elevated temperatures. Its designation identifies a chromium-molybdenum-silicon-vanadium alloy, and it is widely compared with H13 tool steel, 1.2344, and JIS SKD61. These grades are often treated as counterparts, but equivalence is not automatic: confirm the applicable standard, chemistry, product form, and delivery condition before substituting one for another.
Click here to get more.
For buyers, the main advantage of 4Cr5MoSiV1 is its balanced combination of hot strength, resistance to thermal fatigue, and toughness when correctly heat-treated. It is not a stainless steel, despite the chromium in its composition. Below, we explain its GB grade, typical chemistry and properties, common uses, and practical points to check when sourcing it.
At a Glance: Key Takeaways
- 4Cr5MoSiV1 is a Chinese-designated hot-work tool steel used for tooling that experiences heat and repeated thermal cycles.
- Its commonly specified composition includes about 5% chromium, with molybdenum, silicon, and vanadium contributing to high-temperature performance and hardenability.
- It is frequently compared with H13, 1.2344, and SKD61, but buyers should verify standard and technical requirements rather than assume interchangeability.
- Final performance depends on steel cleanliness, section size, machining, heat treatment, and the operating conditions of the tool.
What Is 4Cr5MoSiV1 Steel?
4Cr5MoSiV1 is an alloy tool steel listed in Chinese tool-steel standards, including GB/T 1299. It belongs to the chromium hot-work tool steel family, designed for applications where tooling heats during service and may undergo repeated heating and cooling. The grade is typically supplied as steel for machining into dies, molds, inserts, and related components.
The name gives a broad indication of its alloy system, but it does not replace a material certificate or the relevant standard. The initial “4” relates to a nominal carbon level around 0.4%, while the other characters identify principal alloying elements. Exact permissible composition depends on the standard edition and purchase specification, so use the agreed standard and mill documentation for procurement decisions.
Is 4Cr5MoSiV1 stainless steel?
No. 4Cr5MoSiV1 is a tool steel, not a stainless steel grade. Its chromium content supports hardenability, oxidation resistance at elevated temperatures, and other tool-steel characteristics, but it is far below what would generally be expected in a stainless grade. Do not select it where corrosion resistance is the primary requirement.
GB Grade and Typical Chemical Composition
4Cr5MoSiV1 is the GB designation buyers will commonly see on Chinese-origin material documents. It is often described as comparable to AISI H13, DIN/EN 1.2344, and JIS SKD61 because these grades share a similar hot-work alloy concept. However, standards may differ in permitted chemistry, cleanliness requirements, product form, and testing, so a comparison should be treated as a starting point rather than proof of exact equivalence.
| Element | Typical specification range by mass | General role in the alloy |
|---|---|---|
| Carbon (C) | 0.32–0.42% | Contributes to hardness and strength after heat treatment. |
| Chromium (Cr) | 4.75–5.50% | Supports hardenability and high-temperature performance. |
| Molybdenum (Mo) | 1.10–1.75% | Contributes to hot strength and resistance to softening. |
| Silicon (Si) | 0.80–1.20% | Acts as an alloying and deoxidizing element. |
| Vanadium (V) | 0.30–0.60% | Supports wear resistance and high-temperature strength. |
These ranges are commonly associated with the grade, but buyers should check the precise limits in the specified edition of the governing standard. A supplier’s material test certificate should report the actual heat analysis, not simply repeat a grade name. For safety-critical or tightly controlled tooling, specify any additional cleanliness, inspection, or testing requirements before placing the order.
Properties and Performance
4Cr5MoSiV1 is valued for a combination of properties rather than a single maximum value. Chromium, molybdenum, silicon, and vanadium contribute to performance under hot-work conditions, while heat treatment determines the hardness and toughness achieved in a finished tool. As a result, published or quoted values should be interpreted in relation to the test method, sample size, and condition of the material.
Hot strength and thermal fatigue resistance
During hot-work service, a die surface can experience repeated temperature changes, contact pressure, and cooling. 4Cr5MoSiV1 is used in such environments because its alloy system is intended to retain useful strength at elevated temperatures and resist thermal-fatigue damage. Actual service life still depends on factors such as die design, surface condition, cooling practice, and the temperature cycle.
You will get efficient and thoughtful service from Mingchuan.
Hardness, toughness, and wear
After appropriate hardening and tempering, the steel can provide a balance of hardness and toughness for hot-work tooling. Higher hardness may improve resistance to deformation and wear, but it can also increase sensitivity to cracking if the tool design, heat treatment, or service loading is unsuitable. Buyers should define the required hardness range with the heat treater or toolmaker instead of relying on a generic value detached from the application.
Machinability and heat treatment
Machinability depends on the supplied condition, section dimensions, and cutting process. Tool steel is commonly machined before final hardening, with allowance for dimensional change and finishing after heat treatment where required. Because heating and cooling schedules must account for part size and geometry, heat treatment should be performed to a documented procedure appropriate to the component.
Common Uses of 4Cr5MoSiV1
Typical applications include hot-stamping and forging dies, die-casting molds, extrusion tooling, and other dies or inserts subject to elevated temperatures. It may also be considered for plastic-molding components where a hot-work tool steel’s strength and toughness are relevant, subject to the mold’s specific wear, polish, and corrosion requirements. The best grade depends on the actual operating temperature, loading, cooling method, and expected production conditions.
- Hot forging: Dies and tooling exposed to repeated contact with heated workpieces.
- Die casting: Mold components that face thermal cycling and mechanical stress.
- Hot extrusion: Dies and tooling where elevated-temperature strength is important.
- Other mold components: Inserts and cores where a suitable hot-work tool steel is specified.
How to Choose 4Cr5MoSiV1 for a Project
Confirm the grade and delivery condition
Start by stating the required standard and edition, grade, product form, dimensions, and delivery condition. If your drawing names H13, 1.2344, or SKD61, ask the supplier to confirm the proposed substitution against the chemistry and inspection requirements in your specification. Avoid relying on a grade-name match alone, particularly when multiple standards or customer requirements apply.
Match properties to the working conditions
Share the application, tool dimensions, service temperature range, loading, and heat-treatment plan when requesting a quotation. These details help determine whether 4Cr5MoSiV1 is appropriate and whether additional requirements, such as ultrasonic examination or a particular surface condition, are needed. If corrosion resistance is central to the application, evaluate a suitable stainless or corrosion-resistant mold steel instead.
Review traceability and processing support
Request a material test certificate showing the heat number and chemical analysis, and verify that markings or packaging preserve traceability through delivery. Confirm available stock sizes, cutting tolerances, packaging, and export documentation with the supplier before finalizing the order. At Mingchuan, we can review your grade, dimensions, and application details to discuss suitable supply options and documentation for your sourcing requirements.
Conclusion
4Cr5MoSiV1 is a GB hot-work tool steel used for dies, molds, and tooling that must cope with elevated temperatures and repeated thermal cycles. Its typical alloy profile includes approximately 0.32–0.42% carbon and 4.75–5.50% chromium, alongside molybdenum, silicon, and vanadium. Although it is commonly compared with H13, 1.2344, and SKD61, buyers should verify the applicable standard, actual chemistry, delivery condition, and heat-treatment requirements before treating grades as interchangeable.
To assess whether it fits your project, prepare the required standard, dimensions, application conditions, and any inspection or certification requirements. Mingchuan can use these details to help clarify available material options and prepare a quotation for your review. A precise specification is the most useful next step toward reliable procurement.