SS420

Grade 420 stainless steel is a high-carbon steel with a minimum chromium content of 12%. Like any other stainless steel, grade 420 can also be hardened through heat treatment. It offers good ductility in its annealed state and excellent corrosion resistance properties when the metal is polished, surface grounded or hardened. This grade has the highest hardness - 50HRC - among all the stainless steel grades with 12% chromium. Stainless steel grades that are similar to grade 420 stainless steels include martensitic steels such as the other versions of grade 420, having vanadium, sulphur and molybdenum in their composition, and the grade 440 series. Non-standard grade 420C has carbon content that is little higher than that of grade 420. Martensitic stainless steels are ones with high hardness and high carbon content. These steels are generally fabricated using methods that require hardening and tempering treatments. The operating conditions of martensitic steels are affected by loss of material’s strength at high temperatures, and decrease in ductility at negative temperatures.

Key Properties

The following properties are mentioned for bar products in ASTM A276. The specification may not necessarily be similar for other forms, such as forgings and plate.

Heat Resistance

Grade 420 stainless steels have a scaling resistance at temperatures of up to 650°C. However, temperatures above standard tempering temperature are not suitable for this grade.

Heat Treatment

Annealing – Grade 420 stainless steels can be heated at temperatures from 840 to 900°C, followed by slow furnace cooling at 600°C and then air-cooling.

Process Anneal – Grade 420 can be annealed at 735 to 785°C and air-cooled.

Hardening – This process involves heating grade 420 steels at 980 to 1035°C, followed by air or oil quenching. Oil quenching is usually preferred for heavy metal sections. Tempering is performed at 150 to 370°C to achieve high hardness and good mechanical properties. Grade 420 should not be tempered between 425 and 600°C.

Welding

Grade 420 stainless steels are welded using welding rods, coated with grade 420 metals, to achieve high-strength joints. During the process, steels are pre-heated at 150 to 320°C and post-heated to 610 to 760°C. In the “as welded” condition, parts are welded using grade 309 filler rods to achieve ductile joints. However, grade 309 electrodes or rods are recommended for welding grade 420 steels by AS 1554.6.

Machining

Grade 420 steels can be easily machined in their annealed state, but they are difficult to machine having a hardness greater than 30HRC. One of the most readily available machined alternatives is the free-machining grade 416 steels.

Applications

The key applications of grade 420 stainless steels include

• Shear blades

• Needle valves

• Surgical equipment

• Cutlery

SS410

Grade 410 stainless steels are general-purpose martensitic stainless steels containing 11.5% chromium, which provide good corrosion resistance properties. However, the corrosion resistance of grade 410 steels can be further enhanced by a series of processes such as hardening, tempering and polishing. Quenching and tempering can harden grade 410 steels. They are generally used for applications involving mild corrosion, heat resistance and high strength. Martensitic stainless steels are fabricated using techniques that require final heat treatment. These grades are less resistant to corrosion when compared to that of austenitic grades. Their operating temperatures are often affected by their loss of strength at high temperatures, due to over-tempering and loss of ductility at sub-zero temperatures.

Key Properties

The properties displayed below are applicable to bar products of ASTM A276. Other products such as forgings, wire and plate may not have similar properties.

Heat Resistance

Grade 410 steels have good scaling resistance at temperatures of up to 650 °C. However, the mechanical properties of the material will tend to reduce at temperatures ranging from 400 to 580 °C.

Heat Treatment

Annealing – Grade 410 steels can be fully annealed at temperatures from 815 to 900 °C, followed by slow furnace cooling and air-cooling. Process annealing of grade 410 steels can be carried out at temperatures ranging from 650 to 760 °C and air-cooled

Process Anneal – Grade 420 can be annealed at 735 to 785°C and air-cooled.

Hardening – Hardening of grade 410 steels can be performed at 925 to 1010 °C, followed by air and oil quenching. Heavy sections of grade 410 need to be oil quenched. Tempering, to enhance the mechanical properties and hardness of grade 410 steels, follows this process. It is not recommended to perform tempering at temperatures from 400 to 580 °C

Welding

Grade 410 steels can be welded using all conventional welding techniques, but the materials should pre-heated at 150 to 260 °C followed by post-weld annealing treatment, to mitigate cracking. Grade 410 welding rods are recommended for tempering and post-hardening. In the "as welded" conditions, grade 309 filler rods can be used to achieve a ductile joint.

According to AS 1554.6 standards, grade 309 electrodes or rods are preferred for welding 410 steels.

Machining

Grade 410 steels can be easily machined in highly tempered or annealed conditions. However, it is hard to machine grade 410 steels if they are hardened above 30HRC. Free machining grade 416 is the best alternative.

Applications

Grade 410 stainless steels find applications in the following:

• Bolts, screws, bushings and nuts

• Petroleum fractionating structures

• Shafts, pumps and valves

• Gas turbines

• Mine ladder rungs

SS410S

Stainless steels are high-alloy steels with good corrosion resistance due to large amounts of chromium present in them. Most of the stainless steels contain about 10% of chromium.Stainless steels are available in three different groups based on their crystalline structure. These groups include martensitic, austenitic and ferritic. The combination of martensitic and ferritic steels forms a fourth group of stainless steels known as precipitation-hardened steels.Grade 410S stainless steel is a non-heat treatable version of grade 410 stainless steel.

Grade 410S stainless steel is annealed at 649-760°C (1200-1400°F) and then cooled in airCold Working

Commonly used cold working methods are used for grade 410S stainless steel.

Hot Working

Hardening

Grade 410S stainless steel does not respond to hardening by heat treatment.

Welding

Grade 410S stainless steel can be welded by commonly used welding methods. The workpiece is preheated to 177-204°C (350-400°F) to prevent cracking

Machinability

Grade 410S stainless steel can be machined in the annealed condition though better results are obtained in heat treated and cold drawn conditions.

SS420S2

SUS420J2 is a martensitic stainless steel known for its hardenability through heat treatment, making it suitable for applications requiring high hardness and wear resistance. It's a versatile material used in various fields, often found in components like medical knives, hinges, and springs. When shipped annealed, it has spheroidized carbides, which allows for easy processing.

Key Characteristics

• HardenableSUS420J2 can be hardened by quenching and tempering, achieving high hardness levels.

• Martensitic Belonging to the martensitic stainless steel family, it offers a good balance of strength, hardness, and corrosion resistance.

• Wear Resistant The high hardness achievable through heat treatment makes it suitable for applications where wear resistance is crucial.

• Versatile Its properties make it useful in various applications, including medical instruments, cutting tools, and components requiring good mechanical properties.

• Good Polishability It can be polished to a high gloss finish.

• Corrosion Resistance While not as corrosion-resistant as austenitic stainless steels like 304, it offers good corrosion resistance, especially when polished or hardened.

Applications

• MedicalSurgical instruments, lancets, and medical knives

• Cutting Tools Razors and other cutting implements.

• Industrial Hinges, doctor blades, and springs

• Other Scale, reed, spinning machine components, soldering irons, and scrapers.

• Good Polishability It can be polished to a high gloss finish.

• Corrosion Resistance While not as corrosion-resistant as austenitic stainless steels like 304, it offers good corrosion resistance, especially when polished or hardened.

Composition

• It's a high-carbon steel with a minimum of 12% chromium.

• Other elements like manganese, silicon, and sometimes molybdenum or vanadium can be present in small amounts.

Heat Treatment

• SUS420J2 can be hardened through quenching and tempering

• Achieves its highest hardness after heat treatment

• Annealed condition provides good ductility for processing.