416s21 stainless steel

416s21 stainless steel is a free-machining martensitic stainless steel grade known for its exceptional machinability and moderate corrosion resistance. This article explores its characteristics, applications, and significance in various industrial sectors.


Material Composition:
The typical chemical composition includes:

Carbon: 0.15% max
Chromium: 12-14%
Sulfur: 0.15% min
Manganese: 1.25% max
Phosphorus: 0.06% max
Silicon: 1.00% max
Added sulfides for improved machinability
Key Properties:

Mechanical Properties:
High tensile strength
Good hardness
Excellent machinability
Moderate corrosion resistance
Magnetic characteristics
Physical Properties:
Specific gravity: 7.64
Modulus of elasticity: 200 GPa
Thermal conductivity: 24.9 W/m·K
Specific heat: 460 J/kg·K
Electrical resistivity: 0.57 μΩ·m
Manufacturing Process:
The production involves several steps:

Raw material selection
Melting and refining
Hot forming
Heat treatment
Annealing
Hardening
Tempering
Surface finishing
Quality control
Industrial Applications:

Automotive Industry:
Valve stems
Pump shafts
Fasteners
Bushings
Nuts and bolts
Manufacturing Equipment:
Machine parts
Cutting tools
Precision components
Wear-resistant parts
Consumer Products:
Appliance components
Hardware items
Kitchen equipment parts
Decorative elements
Industrial Machinery:
Shafts
Gears
Bushings
Mechanical components
Machining Characteristics:
416s21 offers superior machinability due to:

High sulfur content
Controlled hardness
Good chip formation
Excellent surface finish
Extended tool life
Heat Treatment:
Proper heat treatment is crucial:

Annealing:
Temperature: 850-900°C
Slow cooling required
Hardening:
Austenitizing: 925-1010°C
Oil or air quenching
Achievable hardness: 35-45 HRC
Tempering:
Temperature range: 150-370°C
Depends on desired properties
Corrosion Resistance:
While not as corrosion-resistant as austenitic grades:

Adequate for mild environments
Resistant to atmospheric corrosion
Suitable for indoor applications
Requires protection in severe conditions
Market Applications:
Common uses include:

Precision Components:
High-speed automatic screw machine parts
CNC machined components
Custom fabricated items
Industrial Equipment:
Pump components
Valve parts
Coupling devices
Mechanical seals
Specialized Applications:
Medical instruments
Laboratory equipment
Food processing equipment
Architectural hardware
Quality Control:
Important quality parameters include:

Dimensional accuracy
Surface finish
Mechanical properties
Chemical composition
Microstructure
Economic Considerations:
Cost factors include:

Material price
Machining efficiency
Tool life
Production speed
Finishing requirements
Advantages:

Processing Benefits:
Excellent machinability
Good dimensional stability
Consistent properties
Easy to heat treat
Performance Benefits:
Reliable strength
Adequate corrosion resistance
Good wear resistance
Magnetic properties
Limitations:
Understanding constraints is important:

Lower corrosion resistance than 300 series
Not suitable for welding
Limited high-temperature use
Specific heat treatment requirements
Future Trends:
The market outlook includes:

Increased automation applications
Advanced machining techniques
New surface treatment methods
Expanded industrial uses
Environmental Impact:
Considerations include:

Recyclability
Energy consumption in production
Waste reduction potential
Long service life
Safety Considerations:
Important safety aspects:

Proper handling procedures
Machining safety guidelines
Heat treatment precautions
Protective equipment requirements