Both 1.4021 and 1.4028 are 13% chromium martensitic stainless steels. Their hardness and strength can be increased through quenching and tempering. Since both grades are commonly classified within the AISI 420 family, they are sometimes mistaken for the same material during material selection or quotation.
However, the two grades are not identical. Grade 1.4021 offers a better balance of strength, toughness, and machinability, while 1.4028 contains more carbon and can achieve higher hardness and better wear resistance after suitable heat treatment.
The European designation for 1.4021 is X20Cr13, while 1.4028 is designated X30Cr13. As their names indicate, the main difference between the two grades is their carbon content.
Element | ||
Carbon (C) | 0.16%–0.25% | 0.26%–0.35% |
Chromium (Cr) | 12.0%–14.0% | 12.0%–14.0% |
Manganese (Mn) | ≤1.50% | ≤1.50% |
Silicon (Si) | ≤1.00% | ≤1.00% |
Phosphorus (P) | ≤0.040% | ≤0.040% |
Sulfur (S) | ≤0.030% | ≤0.030% |
The chromium ranges are essentially the same, so the two grades offer a similar basic level of corrosion resistance. However, the higher carbon content of 1.4028 allows it to achieve greater hardness and wear resistance after quenching. The trade-off is lower toughness and greater sensitivity during welding and heat treatment.
The performance of martensitic stainless steel depends heavily on its delivery condition and heat-treatment process. The soft-annealed condition is mainly used to facilitate machining and forming, while higher hardness and strength are obtained after quenching and tempering. The material condition must therefore be confirmed before comparing mechanical properties.
Property | ||
Soft-annealed hardness | ≤230 HB | ≤245 HBW |
Soft-annealed tensile strength | ≤760 MPa | ≤800 MPa |
Reference hardness after final heat treatment | Approx. 44–50 HRC | Approx. 45–51 HRC |
Wear resistance | Good | Better |
Toughness | Relatively better | Relatively lower |
Grade 1.4021 is generally the better option when a component requires strength together with good toughness and reliable machinability. Grade 1.4028 is more suitable when higher hardness, wear resistance, or edge retention is the main requirement.
The hardness ranges above are intended only as general guidance during preliminary material selection. Actual results depend on material dimensions, quenching temperature, cooling method, tempering temperature, and component geometry. Final requirements should always be confirmed against the drawing or purchase specification.
Because their chromium contents are similar, 1.4021 and 1.4028 provide comparable corrosion resistance in fresh water, steam, and mildly corrosive environments with little or no chloride exposure. Their main advantage is the ability to combine heat-treatment capability with a basic level of corrosion resistance.
Neither grade is intended for seawater, high-chloride conditions, or strongly corrosive environments, and they should not be treated as direct substitutes for 304 or 316 stainless steel. Heat treatment and surface finish also have a significant effect on martensitic stainless steel. Proper quenching and tempering, together with a finely ground or polished surface, generally improves corrosion performance.
Common Applications of 1.4021Grade 1.4021 provides a well-balanced combination of mechanical properties and is widely used for general machinery and equipment components, including shafts, flanges, valve parts, hydraulic components, pump parts, measuring tools, press plates, and wear-resistant components. It is also used for automotive parts, kitchen utensils, selected cutting tools, surgical instruments, energy equipment, and petrochemical machinery. For components with relatively complex shapes, moderate impact loads, or no need for maximum hardness, 1.4021 usually provides a practical balance between manufacturing performance and service properties. |  |
 | Common Applications of 1.4028Grade 1.4028 is better suited to products requiring higher hardness, wear resistance, and edge retention. Typical applications include kitchen knife blades, food-processing knives, industrial blades, shearing tools, cutting tools, and surgical cutting instruments. It can also be used for wear-resistant mechanical parts, pump and valve components, piston rods, screws, and selected automotive and industrial equipment components. When the main requirement is higher hardness, better wear resistance, and longer-lasting cutting edges, 1.4028 is usually the preferred choice. |
The decision should be based on the performance that matters most to the finished component:
Choose 1.4021 when toughness, balanced mechanical properties, and machining reliability are the priorities.
Choose 1.4028 when hardness, wear resistance, and edge retention are more important.
If welding is required, the application should be evaluated carefully, as 1.4028 is more sensitive to welding and heat-treatment conditions.
If the component will be exposed to salt water, seawater, or high-chloride environments, neither grade should be selected without reassessing the required corrosion-resistance level.
If a drawing specifies only “AISI 420,” the carbon range, required hardness, heat-treatment condition, and applicable standard should be confirmed. AISI 420 covers a relatively broad composition range, so the designation alone is not enough to determine whether the intended material is 1.4021 or 1.4028.
Both 1.4021 (X20Cr13) and 1.4028 (X30Cr13) are within our production capabilities. Customers can select the appropriate grade based on the application, drawing dimensions, required hardness, delivery condition, surface finish, and inspection requirements.
If you are unsure which grade is better suited to your application, please send us the intended use, operating environment, dimensions, quantity, hardness requirement, and heat-treatment specifications. We can help you evaluate the material and confirm a suitable production and delivery plan.
The values in this article are general references based on commonly used standards. Final chemical composition, mechanical properties, and delivery conditions shall be subject to the agreed standard, drawing, purchase order, and material test certificate.
