Stainless Steel 420 Machined Parts
A Guide to 420 CNC Milled & Turned Parts
What is stainless 420?
Stainless 420 is a general purpose high carbon martensitic steel. It is usually supplied hardened and tempered or annealed condition. Martensitic stainless steels are designed for high hardness and sometimes other properties are compromised on.
420 has the highest hardness amongst all stainless grades with 12% chromium. The addition of sulphur to improve machinability does lower the corrosion resistance and weldability to below that of grade 410 (non-free machining equivalent).
Main Attributes of 420:
- Rust resistant
- High hardness
- Exceptional wear resistance
- Good corrosion resistance achieved when hardened and surface ground or polished (to atmosphere, foods, fresh waters, mild acids)
- Although it can be used in continuous service up to 650°C, this can result in a considerable drop in its core properties (hardness, tensile strength, corrosion resistance), therefore not recommended for use at working temperatures above 400°C
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Stainless 420 Machining Characteristics
Stainless 420 machines best in the hardened and tempered condition R or condition S. It is similar to machining high carbon tool steels in that it gives tough, stringy chips. There is a free-machining type of 420 but this does come at the expense of other properties.
Finishing & Treatments
Stainless 420 is usually supplied in a heat treated condition:
- Annealing – annealed at temperatures between 840-900°C
- Tempering – temper at temperatures between 145-205°C
- Hardening – soak at 1010-1065°C
Similar or obsolete designation and trade names
You may also see stainless 420 referred to as:
- British Standard Grades:
- 420S37 (1.4021)
- European Specifications:
- Related Specifications:
- 1.4021 (Bar)
- UNS S42000
- ASTM A276
- BS EN 10088
- AISI BS970
- UNS X20Cr13
420 Components, Applications & Industries
Here are some examples of the industries and components for which stainless 420 is appropriate. This is by no means an exhaustive list. Please do get in touch if you are considering using 420 and we can talk through your project with you.
Typical Components & Applications:
- Surgical and dental instruments
- Cutting tools
- Wear plates
- Needle valves
- Hand tools
- Pump parts
- Valve parts
- Food processing
420 Machining Service
Penta Precision provides highly accurate machined parts in 420. Customers turn to us when they have had quality and delivery issues with their existing suppliers and need a reliable precision machining partner.
Penta Precision provides the following +17/4PH services:
- CNC milling – prototypes & large batch runs
- CNC turning – prototypes & large batch runs
- Insert installation
- Part marking
- Manual milling
- Manual turning
- Machining design advice
- Machining drawing service
Reasons to Choose Penta:
- ISO 9001:2015 quality assurance
- Consistent high quality machined parts
- Reliable delivery dates - our track record speaks volumes
- Exceptional customer service and communication
- Machining design advice
- Extensive experience in our field
What Makes Penta Different?
Our 3 unique pillars to delivering exemplary service:
We are regularly machining 420 for customers all over the UK. Our customers depend on our machining expertise as well as our outstanding delivery performance, to machine the highest quality parts. If you'd like to discuss how we can help you with your 420 machining requirements, here's a list of ways to get in touch with us.