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Manufacturing services
CNC milling and turning · From 1 part
Mold inserts and cavities, blades, valve parts, pump shafts, instruments and wear parts in 420 stainless steel, machined from your file. Upload your CAD and order online, starting at a single part.
Mold cavity insert
420 Stainless · 70 × 50 × 25 mm · 40 × 24 × 8 mm cavity · 2 Ø5 ejector pin holes · 4 M6 threads · CNC milled
1 pc
$146.50 USD
per part
25 pcs
$48.40 USD
per part
-66.96%100 pcs
$44.00 USD
per part
-69.97%420 stainless steel (UNS S42000, ASTM A276 / A240) is a martensitic stainless steel with 12–14% chromium and at least 0.15% carbon that hardens by quenching and tempering to about 50 HRC and polishes to a mirror finish. It is bought annealed, machined and, if the drawing calls for it, hardened. It is magnetic. At PREMSA we CNC mill and turn it from your file: mold inserts and cavities, blades, valve parts, pump shafts and wear parts, starting at a single part with an instant price.
Engineering-grade properties of 420 stainless steel, including mechanical, physical and heat treatment characteristics for hardened parts, mold inserts, wear parts and machined components.
Alloy Type
Martensitic stainless steel (13% chromium, 0.15% carbon min)
Primary Characteristics
Hardens by quenching and tempering, high hardness, good wear resistance, polishes to a mirror finish, moderate corrosion resistance, magnetic
Tensile Strength (Ultimate)
Annealed: about 655 MPa (95 ksi) · Hardened and tempered at 200 °C: about 1,600 MPa (230 ksi)
Tensile Strength (Yield)
Annealed: about 345 MPa (50 ksi) · Hardened and tempered at 200 °C: about 1,360 MPa (195 ksi)
Elongation at Break
Annealed: about 25% · Hardened and tempered: about 8–12%
Hardness
Annealed: 241 HB max · Hardened and tempered: up to about 50 HRC, depending on carbon and temper
Density
7.74 g/cm³ (0.280 lb/in³)
Elastic Modulus
200 GPa (29,000 ksi)
Poisson’s Ratio
0.27
Thermal Conductivity
24.9 W/m·K at 100 °C
Coefficient of Thermal Expansion
10.3 µm/m·°C
Specific Heat
460 J/kg·K
Melting Range
1450–1510 °C (2640–2750 °F)
Machinability
Good when annealed; hardened it machines more slowly, with carbide tooling
Formability
Moderate when annealed
Weldability
Limited: needs preheating to 150–320 °C and tempering after welding
Corrosion Resistance
Moderate: withstands air, fresh water, food and mild acids; hardened and polished is how it resists best; it rusts with chlorides
Heat Treatment
Hardened from 980–1,035 °C in oil or air and tempered at 150–370 °C; tempering between 425 and 550 °C is avoided (it lowers toughness)
Common Forms
Round bar, flat bar, plate and sheet
Typical Applications
Plastic molds and inserts, blades, surgical and dental instruments, valve parts, pump shafts, wear parts
Material Composition
Chromium 12.0–14.0%, carbon 0.15% min (typically 0.15–0.40%), manganese 1.00% max, silicon 1.00% max, phosphorus 0.040% max, sulfur 0.030% max, balance iron
ASTM Standard
ASTM A240 / A276
Rating across key engineering and manufacturing criteria.
Strength
Weight
Machinability
Formability
Weldability
Corrosion Resistance
Wear Resistance
Cost Efficiency
Upload your CAD file and get an instant price and delivery date. CNC milling and turning from one part to production.
We CNC mill and turn 420 stainless parts that have to be hardened, polished and resist rust.
Mold inserts and cavities
Mold plates
Blades
Surgical and dental instruments
Valve parts
Pump shafts
Wear parts
Bushings and guides
Custom 420 parts
What people ask most about 420 stainless steel parts: what it is, what it is used for, composition, hardness, hardening, equivalents, density, magnetism, rust, price and tolerances.
420 stainless steel is chosen for parts that have to be hardened, polished and not rust: plastic mold inserts and cavities, blades, instruments, valve parts and pump shafts. It is bought annealed, machined and, if the drawing calls for it, hardened and tempered.
At PREMSA Industries we machine 420 with CNC milling and turning from your file, from a prototype to production.
420 is chosen when the part needs hardness, a good polish and wear resistance, and also has to be stainless.
If your drawing doesn’t specify tolerances, we machine to ISO 2768-m (medium). On dimensions you call out —cavities, holes, fits and parting surfaces— we can hold ±0.025 mm (±0.001 in), and critical dimensions are checked in inspection. If the part is hardened after machining, hardening moves it: tight dimensions are left with stock and ground or finished after hardening.
420 is machined with CNC milling, CNC turning, drilling and tapping, preferably annealed.
After machining, the part is hardened from 980–1,035 °C in oil or air and tempered to the hardness on the drawing: a low temper (150–370 °C) leaves it hard and polishable, a high temper makes it tougher. We machine the part and, if you ask, send it out for hardening.
420 is welded with care.
For its hardness, its polish and because it is stainless, 420 is used in many parts made with CNC machining.
420 is usually the right choice when the part has to be hardened and polished and can’t rust in a moderate environment.