SS 420J2 — Stainless Steel (SS) Grade Specification, Properties & Equivalents
SS 420J2 is a high-carbon martensitic stainless steel widely recognized in India for its exceptional hardness, wear resistance, and the ability to hold a sharp edge. With a nominal chromium content of around 13%, SS 420J2 offers adequate corrosion resistance for many applications
SS 420J2 is a high-carbon martensitic stainless steel widely recognized in India for its exceptional hardness, wear resistance, and the ability to hold a sharp edge. With a nominal chromium content of around 13%, SS 420J2 offers adequate corrosion resistance for many applications, especially when polished and hardened. It is heat-treatable, allowing fabricators and manufacturers across India to achieve a wide range of mechanical properties tailored to specific needs, from brittle sharpness to a tougher, strong state. Key industries in India, including surgical instrument manufacturers, cutlery makers, and precision engineering firms, rely heavily on SS 420J2 for components demanding superior cutting ability and durability. Its cost-effectiveness compared to higher alloyed steels makes SS 420J2 a preferred choice for demanding, yet budget-conscious, B2B procurement.
Chemical Composition of SS 420J2
SS 420J2 - Chemical Composition
| Element | % Range | |
| Carbon (C) | 0.30 - 0.40 | |
| Manganese (Mn) | ≤ 1.00 | |
| Silicon (Si) | ≤ 1.00 | |
| Phosphorus (P) | ≤ 0.040 | |
| Sulfur (S) | ≤ 0.030 | |
| Chromium (Cr) | 12.0 - 14.0 | |
Note: Chemistry is indicative of JIS G4303 standard for SUS420J2, commonly mirrored in other specifications.
Mechanical Properties of SS 420J2
SS 420J2 - Mechanical Properties
| Property | Value (Hardened & Tempered) |
| Ultimate Tensile Strength (UTS) | 850 - 1100 MPa |
| Yield Strength (YS) (0.2% offset) | 650 - 900 MPa |
| Elongation at Break | 10 - 15 % |
| Hardness (HRC) | 48 - 55 |
| Hardness (HB) (Annealed) | 170 - 210 HB |
| Modulus of Elasticity | 190 - 200 GPa |
| Density | 7.75 g/cm³ |
Note: valores are typical for fully hardened and tempered SS 420J2; specific values depend on heat treatment.
Available Forms in India for SS 420J2
| Shape | Typical Sizes (mm) | Standard Length (m) |
| Round Bars | 6.0 - 100.0 OD | 3 - 6 |
| Flat Bars / Strips | 3.0 x 15.0 to 10.0 x 50.0 | 3 - 6 |
| Sheets / Plates | 0.8 - 5.0 (Thickness) | 1.2 x 2.4 / 1.5 x 6.0 |
| Wire Rod | 2.0 - 6.0 Dia | Coils |
Availability of specific sizes for SS 420J2 can vary; custom lengths are often possible.
Real-world Applications of SS 420J2
- Surgical & Dental Instruments: SS 420J2 is used for scalpels, forceps, and bone saws due to its hardness and corrosion resistance after hardening.
- Cutlery & Knife Blades: High hardness makes SS 420J2 ideal for kitchen knives, pocket knives, and industrial blades requiring a sharp edge.
- Scissors & Shears: The ability to achieve a fine, durable edge makes SS 420J2 a common choice for various types of scissors.
- Needle Valves & Pump Parts: In moderately corrosive environments, SS 420J2 finds use in components requiring wear resistance.
- Shafts & Spindles: For applications needing good strength and surface hardness, SS 420J2 is employed in shafts and spindles.
- Moulds & Dies: Its workability and hardness make SS 420J2 suitable for certain types of plastic injection moulds and stamping dies.
- Measuring Instruments: Precision tools like calipers and micrometers benefit from the dimensional stability and wear resistance of SS 420J2.
- Metalworking Tools: Punches, dies, and other stamping tools utilize the hardness of SS 420J2 for extended service life.
Machinability & Weldability of SS 420J2
Machining SS 420J2 requires careful consideration of its heat treatment state. In its annealed condition (typically around HB 200), SS 420J2 machines readily, comparable to other medium-carbon steels. Standard machining practices with appropriate speeds, feeds, and robust tooling are effective. However, after hardening and tempering to achieve high hardness, machinability drops considerably. For hardened SS 420J2, it is often more practical to use grinding techniques for finishing rather than traditional machining. If machining is unavoidable in the hardened state, significantly lower cutting speeds, increased coolant flow, and specialized tooling designed for hard metals are essential. Weldability of SS 420J2 is generally considered poor, especially in the hardened condition. It is prone to cracking in the heat-affected zone due to its high carbon content and martensitic structure. If welding is necessary, SS 420J2 should ideally be welded in the annealed condition using preheating (around 150-250°C) and low-hydrogen electrodes or filler metals, such as matching stainless steel electrodes (e.g., E/ER 420). Post-weld heat treatment, including slow cooling and potentially a tempering cycle (around 600-700°C), is crucial to relieve stresses and minimize cracking risk. However, welding is often avoided in favour of mechanical joining methods for SS 420J2 components.Heat Treatment & Processing of SS 420J2
The processing of SS 420J2 heavily relies on heat treatment to achieve its desired properties. Annealing is typically performed at 800-850°C followed by slow furnace cooling to obtain a soft, machinable structure (approx. 170-210 HB). For hardening, SS 420J2 is heated to 980-1050°C and quenched in oil or air to form a hard martensitic structure. The specific austenitizing temperature and hold time depend on the section thickness and desired hardness. Tempering follows hardening to reduce brittleness and improve toughness, with temperatures ranging from 150°C (maximum hardness, lower toughness) to 300°C (balanced properties). Higher tempering temperatures above 300°C lead to a significant drop in hardness and corrosion resistance, making them generally unsuitable for SS 420J2's primary applications. Normalizing, if required, is typically done around 900-950°C followed by air cooling. Stress relieving can be performed at 600-650°C. Proper heat treatment is critical for unlocking the performance potential of SS 420J2.Sourcing SS 420J2 in India
SS 420J2 is readily available in the Indian market from major domestic producers like Jindal Stainless, SAIL, and smaller specialized rolling mills. Stockists and suppliers in major industrial hubs like Mumbai, Pune, Chennai, and Ahmedabad maintain significant inventories. SS 420J2 is typically sourced in forms such as round bars, flat bars, and sheets. Minimum Order Quantities (MOQs) can range from 100 kg for smaller custom-cut pieces to 500-1000 kg for standard mill lengths or sheets. The price band for SS 420J2 generally falls between INR 250 - 350 per kg, depending on the form, quantity, and prevailing market conditions. Buyers should always expect Mill Test Certificates (MTC) as per IS/JIS standards, confirming chemical composition and mechanical properties, with Positive Material Identification (PMI) available upon specific request.International Equivalents for SS 420J2
| Country/Standard | Grade/Code |
| Japan (JIS) | SUS420J2 |
| USA (ASTM) | 420 (similar properties, slight variations) |
| Europe (EN) | X30Cr13 / 1.4028 |
| China (GB) | 40Cr13 |
FAQs about SS 420J2
What is SS 420J2 stainless steel and what are its key properties?
SS 420J2 is a martensitic stainless steel known for its high hardness, good strength, and moderate corrosion resistance, especially after heat treatment. It contains around 13% Chromium and 0.40% Carbon, allowing it to achieve excellent wear resistance and edge retention, making it a popular choice for cutting tools and instruments in India. Its balance of properties makes SS 420J2 a workhorse for many applications where durability is key.
What are the primary applications of SS 420J2 in India?
SS 420J2 is widely used in India for manufacturing surgical and dental instruments (scalpels, forceps), high-quality cutlery and knife blades, scissors, and various precision tools. Its ability to be hardened to a high degree ensures sharp edges and excellent wear resistance, crucial for these demanding applications. Fabrication using SS 420J2 requires attention to its hardenability.
How is SS 420J2 heat treated to achieve its characteristic hardness?
The hardness of SS 420J2 is typically achieved through heat treatment. After annealing, it can be hardened by heating to 980-1050°C followed by quenching in oil or air. The final hardness depends on the tempering temperature, usually between 150-300°C, which also affects toughness. For SS 420J2, achieving HRC 50+ is common for cutting tools.
What is the corrosion resistance of SS 420J2?
While SS 420J2 offers moderate corrosion resistance due to its chromium content, it is not as resistant as austenitic grades like 304 or 316. It is susceptible to staining in harsher environments. For optimal corrosion resistance in India, SS 420J2 should be used in a hardened and polished condition. It performs best in mildly corrosive atmospheres or when cleanliness is maintained.
Can SS 420J2 be machined and welded?
Yes, SS 420J2 can be machined, but it requires care. In the annealed state, it machines similarly to other medium-carbon steels. However, after hardening, its machinability decreases significantly. It's best to machine SS 420J2 in the annealed or softened condition before hardening and tempering. If machining after hardening is necessary for SS 420J2, slower speeds and robust tooling are recommended. Grinding is often preferred for final finishing.
Tags: grade, stainless steel (ss), ss 420j2