Stainless steel is an irrevocable modern alloy of today's economy. Its distinctive characters recreate applications in the era of industrial engineering. Stainless steel is a recycled substantial amalgamation.

Stainless steel alloys are distinguished by the occurrence of chromium that offers superior corrosion resistance. Stainless steel contains 10.5% chromium at least. Levels of chromium, with additional alloying agents like molybdenum, nickel, titanium, etc determine the mechanical properties of stainless steel.

400 series includes Ferritic and Martensitic steel. Grade 420 is martensitic stainless steel.  

Martensitic stainless steel is a high carbon, plain chromium steel with 12-18% chromium. It contains high carbon than ferritic or austenitic stainless steel. It offers strength, moderate corrosion resistance, and wear resistance. Martensitic stainless steel shows good ductility and machinability.

AISI 420 STAINLESS STEEL

Basically, grade 420 is an alteration of grade 410 with higher carbon content to increase hardness, strength, and wear resistance. Grade 420 is a high-carbon and low chromium stainless steel. Like all 400-grade series stainless steel, grade 420 stainless steel can be hardened by heat treatment. It exhibits corrosion resistance and good ductility in annealed conditions. Grade 420 is not weld generally, although welding can be done with precautions. Grade 420 has a hardness of 50HRC. It is the highest level of hardness among all low chromium stainless steel. It has a scaling temperature of around 650°C. 

Grade 420 is martensitic stainless steel. Generally, martensitic steel has high carbon content and poses optimum hardness. Fabrications of martensitic stainless steel required hardening and tempering operations. Grade 420 is not used for temperatures beyond 427°C, as it attains softness and loss of corrosion resistance.

Good corrosion resistance and hardness are the attributes that make it ideal for its application. Grade 420 is widely used in cutlery, bushings, surgical and dental instruments, scissors, pump and valve parts, etc.

COMPOSITION

Grade 420 is high carbon and low chromium stainless steel. It contains 12-14% chromium with nickel, sulfur, and molybdenum in composition.

PHYSICAL PROPERTIES

Grade 420 attains a metric density of 7.74 g/cm3. 

The modulus of elasticity is 200Gpa.

Electrical resistivity is 68 Microhm-cm.

Melting point range: 1454-1510 °C

THERMAL PROPERTIES

Thermal expansion coefficient is 10.2 µm/m° at 1-100°C 

 Thermal conductivity is 24.9 W/mK at 100°C and 28.7 W/mK at 500°C.

MECHANICAL PROPERTIES

In annealed conditions, Grade 416 attains a tensile strength of 655 Mpa and yield strength of 345 Mpa. 

Rockwell Hardness is 88B. 

Elongation is 25% in 50mm.

MAGNETIC PROPERTIES

Grade 420 shows magnetic permeability in annealed and heat-treated conditions.

HEAT TREATMENT

 

Annealing

Grade 420 can be annealed by heating its temperature from 840-900 °C. Then slow furnace cooling takes plate till 600°C, followed by air cool.

 Hardening

Material is heated in a temperature range of 980-1035 °C, followed by oil quenching.

Oil quenching is suggested for heavy segments.

 Tempering

Tempering is done in the temperature range of 150-370°C. Tempering at this temperature enables high hardness and improved mechanical properties.

PROPERTIES

CORROSION RESISTANCE 

Grade 420 attains maximum corrosion resistance under hardened conditions. It offers good corrosion resistance in mild environments. Grade 420 offers corrosion resistance to freshwater, alkalis, air, food, and mild acid. It provides corrosion resistance ammonia, blood, sterilizing solutions, carbonic acids, crude oil, detergents, dilutes nitric acids, steam, and vinegar.

A polished and smooth surface finish tends to give excellent results. The corrosion resistance property of grade 420 falls under annealed conditions. It is not suggested to be used in the annealed condition.

Austenitic grades offer more corrosion resistance than grade 420. 

HEAT RESISTANCE 

Grade 420 has a scaling temperature up to 650°C. Tempering is not recommended above this temperature.

WELDING 

Grade 420 emits limited weldability, as it has a hardened structure. However, welding can be done with some modifications.

Material is pre-heated at 150-320°C and post heated to 610-760°C. 

Grade 309 electrodes or rod are suggested for welding for grade 420.

MACHINABILITY

It is easy to machine grade 420 in the annealed condition. 

APPLICATIONS

Good corrosion resistance and hardness are the attributes that make it ideal for its application. Grade 420 is commonly used in dental and surgical instruments. Grade 420 is also called surgical steel. Other common applications for grade 420 are as follows:

• Shear blades
• Surgical equipment
• Cutlery
• Pump shafts
• Needle valves
• Knife blades
• Hand tools
• Fasteners

 

Ambica steels offer superior fine quality grades 416 bars. Bars are available in round, square, flat, hexagonal, and customized shapes. Inquiry and orders are welcome.