420 stainless steel is a common stainless steel material, its main components are chromium (12%~14%), carbon (0.15%~0.40%), silicon (less than 1%), manganese (less than 1%), phosphorus (0.04 % or less), sulfur (less than 0.03%), etc. 420 stainless steel has high hardness and wear resistance, as well as good corrosion resistance, and can be used to manufacture knives, blades, surgical instruments, bearing components, assembly parts, etc. The material is also easy to process and plastic, and can be easily processed into products of various shapes and sizes through cutting, forging, heat treatment and other processes.

Chemical composition of 420 stainless steel

material

420

chemical composition

C

Mn

Si

P

S

Cr

≧0.15

≦1.00

≦1.00

≦0.040

≦0.03

12.0-14.0

Mechanical properties of 420 stainless steel

material

420

mechanical properties

Tensile Strength (MPa)

Yield Strength
0.2% Proof (MPa)

Elongation (% in 50mm)

Hardness Brinell (HB)

Impact Charpy V (J)

655

345

25

241 max

–

Physical properties of 420 stainless steel

material

420

Physical Properties

 

Density (kg/m3)

Elastic Modulus (GPa)

Mean Coefficient of Thermal Expansion
(μm/m/°C)

Thermal Conductivity
(W/m.K)

Specific Heat 0-100°C
(J/kg.K)

Electrical Resistivity (nΩ.m)

0-100°C

0-315°C

0-538°C

at 100°C

at 500°C

7800

200

10.3

10.8

11.7

24.9

–

460

550

The main characteristics of 420 stainless steel

420 stainless steel is a high carbon stainless steel with the following key properties:

High hardness: 420 stainless steel has high hardness, which can be obtained through heat treatment. This makes it widely used in the manufacture of knives, surgical instruments and industrial parts.

Good corrosion resistance: 420 stainless steel has good corrosion resistance and can resist the attack of many chemicals, including some acids and salt solutions. However, compared with other stainless steels, 420 stainless steel has relatively low corrosion resistance.

Easy to process: 420 stainless steel has good plasticity and machinability before heat treatment, and it is easy to perform processing operations such as forging, cold drawing, milling and cutting.

Excellent grinding properties: 420 stainless steel has good grinding properties, so it can be used in the manufacture of knives and blades and other applications that require sharp cutting edges.

Medium strength and wear resistance: 420 stainless steel has moderate tensile strength and wear resistance, making it widely used in the manufacture of parts that require wear resistance.

It should be noted that due to the high carbon content and low chromium content, 420 stainless steel may have corrosion problems in some extreme environments (such as high temperature and strong corrosive environments). Therefore, it needs to be evaluated and selected according to specific application scenarios.

Heat resistance of 420 stainless steel

420 stainless steel is a medium carbon (0.15% to 0.40%) chromium stainless steel with good heat resistance. Its heat resistance depends on the content of its alloy elements and heat treatment process.

Generally, 420 stainless steel has limited heat resistance and is more suitable for low temperature working environments. Its maximum operating temperature is usually 650°C. Beyond this temperature range, stainless steel will begin to precipitate nitrides, resulting in excessive grain growth and intergranular corrosion, and in severe cases, it will increase the thermal embrittlement of the material.

If it is necessary to improve the heat resistance of 420 stainless steel, heat treatment processes such as solution treatment and quenching annealing can be performed. These treatments can improve the material’s grain boundary structure and grain size, thereby improving its heat resistance.

In general, the heat resistance of 420 stainless steel is lower compared with other heat-resistant stainless steels, and it is suitable for use in low temperature environments. In high temperature applications, it is recommended to choose stainless steel materials with better heat resistance.

Heat Treatment of 420 Stainless Steel

420 stainless steel is a high carbon content stainless steel with excellent corrosion resistance and mechanical properties. It can further improve its properties by heat treatment. Grade 420 stainless steel is heated to 840 to 900°C using an annealing process, followed by slow furnace cooling at 600°C and finally air cooling. For process annealing, 420 grade steel is heated to 735 to 785°C and then air cooled. During hardening, grade 420 steel is heated to 980 to 1035°C and then air or oil quenched. Temper at 150 to 370°C for high hardness and good mechanical properties, but avoid tempering between 425 and 600°C.

Welding of 420 stainless steel

For high-strength joints, rod-welded 420-grade stainless steel is used, coated with 420-grade metal. The steel is preheated at 150°C to 320°C and then heated at 610°C to 760°C. During welding, grade 309 filler rods are used for filling to obtain a good ductile joint. However, grade 309 electrodes or wires are used to weld grade 420 steel, as recommended by AS 1554.6.

Processing of 420 stainless steel

420 stainless steel is a high carbon stainless steel, 420 grade steel is easy to machine in the annealed state, but difficult to machine when the hardness is greater than 30HRC. The following are common processing methods for 420 stainless steel:

Cutting: 420 stainless steel is cut using a shear, cutter or EDM. Make sure the cutter has the proper cutting power and the knives are sharp.

Welding: Use a welding method suitable for stainless steel, such as TIG welding or MIG welding. Pay attention to temperature control during the welding process to avoid annealing or oxidation of the steel.

Bending: Bending 420 stainless steel sheet or rod into the desired shape using a mechanical bending machine or hand bending tools. Pay attention to choosing an appropriate bending radius to avoid cracks during bending.

Milling: 420 stainless steel is milled using a milling machine or gantry machining center. Choose the right tool and cutting parameters to ensure a smooth cutting process and smooth surfaces.

Grinding: Grind the 420 stainless steel surface to the desired finish using a grinder, polisher, or hand sandpaper. Choose grinding wheels or sandpaper with different grain sizes according to your needs.

Drilling: Drilling operations are performed using a drill press or a hand-held electric drill. Use cobalt or titanium drills to ensure stable cutting and cooling lubrication.

Turning: 420 stainless steel is turned using a lathe. Select the proper turning tool, cutting speed and feed to achieve the desired precision and surface finish.

Before any processing, be sure to select the appropriate process and equipment according to the specific situation, and follow the corresponding safety operating procedures.

Application fields of 420 stainless steel

420 stainless steel is a high carbon stainless steel mainly composed of chromium, carbon and molybdenum, which has good corrosion resistance and strength. It has a wide range of applications in many industries, including:

Knife manufacturing: 420 stainless steel has good cutting performance and hardness, and is often used in the manufacture of medical devices such as blades, handles, knives, and scalpels.

Pressure vessel: Due to its excellent corrosion resistance and high strength, 420 stainless steel is widely used in the manufacture of pressure vessels, storage tanks and pipelines in chemical, petroleum, natural gas and other fields.

Food processing equipment: 420 stainless steel meets hygienic standards, has excellent corrosion resistance and easy machinability, and is often used in the manufacture of food processing equipment, knives and cutting utensils.

Aerospace: The strength and corrosion resistance of 420 stainless steel make it an important material in the aerospace industry, where it is used to make aircraft parts, propellers, shafts, and more.

Chemical equipment: Because 420 stainless steel can resist the erosion of strong acid, alkali, salt and other corrosive media, it is widely used in the chemical industry to manufacture chemical equipment, storage tanks, pipelines, etc.

Medical equipment: 420 stainless steel has good corrosion resistance, high temperature strength and low temperature toughness, and is widely used in the manufacture of medical equipment, surgical equipment, dental equipment, etc.

All in all, 420 stainless steel has a wide range of applications, including tool manufacturing, pressure vessels, food processing equipment, aerospace, chemical equipment, and medical equipment.