Stainless steels are an integral part of modern industry, engineering, and construction. Among the wide range of stainless steel grades, SS 420 stands out as one of the most popular martensitic stainless steels due to its excellent strength, wear resistance, and moderate corrosion resistance. One of the most widely used product forms of this alloy is the SS 420 round bar, which finds applications across various industries such as automotive, aerospace, construction, medical equipment, and general engineering.
This article provides a comprehensive guide on everything you need to know about SS 420 round bars, including their chemical composition, mechanical properties, manufacturing process, applications, advantages, and sourcing tips.
SS 420 round bar is a cylindrical bar manufactured from grade 420 stainless steel. Classified as a martensitic stainless steel, SS 420 is known for its high hardness and excellent polishability. It contains a higher carbon content compared to austenitic grades, which allows it to achieve remarkable strength after heat treatment.
420 stainless steel round bars are widely available in hot rolled, cold drawn, peeled, and centerless ground conditions. They are produced in various diameters, tolerances, and surface finishes to meet the demands of different industries.
The composition of SS 420 is carefully balanced to provide the required mechanical and corrosion resistance properties. Typical composition includes:
Carbon (C): 0.15% – 0.40%
Chromium (Cr): 12% – 14%
Manganese (Mn): up to 1%
Silicon (Si): up to 1%
Phosphorus (P): up to 0.04%
Sulfur (S): up to 0.03%
Iron (Fe): Balance
The high chromium content gives SS 420 its stainless properties, while carbon enhances hardness and strength.
When heat treated properly, SS 420 round bars can reach impressive hardness levels. The mechanical properties typically include:
Tensile Strength: 700 – 950 MPa
Yield Strength: 400 – 600 MPa
Elongation: 15 – 20%
Hardness (Brinell): 180 – 230 HB (annealed), up to 500 HB (hardened)
These properties make SS 420 round bars suitable for high-stress and wear-resistant applications.
The production process of SS 420 round bars involves several steps:
Melting and Casting: Raw materials are melted in an electric arc or induction furnace, then cast into billets.
Hot Rolling: Billets are hot rolled into round shapes of various sizes.
Heat Treatment: Annealing, quenching, and tempering improve hardness and toughness.
Cold Working: Cold drawing or peeling is used to achieve precise dimensions and better surface finish.
Finishing: Centerless grinding, polishing, or machining ensures a smooth surface for critical applications.
Inspection: Every batch is tested with ultrasonic, mechanical, and chemical analysis to meet international standards.
Heat treatment is the most critical step in enhancing the properties of SS 420 round bars:
Annealing: Heated to 840 – 900°C followed by slow cooling. Improves machinability.
Hardening: Heated to 980 – 1030°C and quenched in oil or air. Increases hardness.
Tempering: Reheating at 150 – 370°C reduces brittleness while maintaining strength.
This versatility allows manufacturers to tailor SS 420 round bars for specific applications.
Due to their strength, durability, and resistance to wear, SS 420 round bars are used in a wide range of industries:
Automotive Industry: Shafts, gears, and valve components.
Aerospace: Turbine blades, fasteners, and mechanical parts.
Medical Instruments: Surgical tools, dental equipment, and scissors.
Construction: Structural supports, fasteners, and decorative hardware.
Industrial Tools: Knives, cutting tools, and measuring instruments.
Marine Applications: Pump shafts and propeller components (with protective coatings).
SS 420 round bars offer several benefits that make them an attractive choice for manufacturers and engineers:
High hardness and tensile strength.
Good wear and abrasion resistance.
Moderate corrosion resistance in fresh water and mild atmospheres.
Excellent polishability, making them ideal for decorative and surgical applications.
Cost-effective compared to higher alloyed stainless steels.
While versatile, SS 420 does have some limitations:
Lower corrosion resistance compared to austenitic grades like 304 or 316.
Not suitable for highly acidic or chloride-rich environments.
Requires heat treatment to achieve optimal properties.
Lower toughness at sub-zero temperatures.
SS 420 round bars are manufactured according to international standards to ensure quality and consistency. Some common specifications include:
ASTM A276 / A479: Stainless steel bars and shapes.
EN 10088-1 / 3: Stainless steels for general purposes.
DIN 1.4021 / 1.4034: German standards equivalent to SS 420.
JIS SUS420J1 / SUS420J2: Japanese standards.
These ensure that the round bars meet global requirements for chemical composition, mechanical properties, and dimensions.
Depending on the application, SS 420 round bars are available in various surface finishes:
Black (Hot Rolled): Scaled surface, used in general engineering.
Bright (Cold Drawn): Smooth surface, better tolerance.
Peeled or Turned: Improved finish and dimensional accuracy.
Ground and Polished: Used for precision engineering and aesthetic purposes.
When sourcing SS 420 round bars, quality, certification, and reliability are key. As a global stainless steel supplier, sakysteel provides high-quality SS 420 round bars that meet ASTM, EN, and JIS standards. With strict quality control, professional packaging, and on-time delivery, customers can be assured of receiving premium materials for their projects.
Whether you need small quantities for testing or bulk orders for industrial applications, sakysteel ensures consistent quality and competitive pricing.
Before purchasing, consider these factors:
Application Requirement: Check if hardness or corrosion resistance is the priority.
Size and Tolerance: Choose appropriate diameter and tolerance.
Heat Treatment Condition: Select annealed, hardened, or tempered as per requirement.
Certification: Ensure EN 10204 3.1 / 3.2 test certificates are provided.
Supplier Reliability: Work with trusted suppliers with proven track records.
Although SS 420 round bars have stainless properties, proper care enhances their service life:
Avoid prolonged exposure to strong acids and chlorides.
Regular cleaning helps maintain corrosion resistance.
Use protective coatings for marine applications.
Store in dry and ventilated areas to prevent rusting.
The demand for SS 420 round bars is expected to increase due to the growth of the automotive, medical, and construction industries. Rising infrastructure projects, advanced surgical tools, and precision engineering will further boost consumption. With advancements in processing technologies, SS 420 round bars will continue to evolve to meet the stringent requirements of modern industries.
SS 420 round bars are a versatile and reliable stainless steel product with a wide range of applications. Their balance of hardness, strength, and polishability makes them suitable for everything from surgical instruments to industrial tools. By understanding their properties, manufacturing process, and usage, buyers can make informed decisions when sourcing these products.
For engineers, manufacturers, and distributors looking for a cost-effective yet high-performance stainless steel solution, SS 420 round bars are an excellent choice.