Stainless Steel 431 Powder

Overview

Stainless Steel 431 Powder is a martensitic stainless steel that contains high chromium content with additions of aluminum and nickel to provide optimum corrosion resistance and mechanical properties. Stainless steel 431 powder metallurgy allows fabrication of high performance parts through methods like metal injection molding.

Some key properties and characteristics of stainless steel 431 powder include:

• High hardness and strength
• Excellent corrosion resistance
• Good wear resistance
• High temperature resistance
• Can be used for parts with complex geometries
• Allows modifications through heat treatment

Stainless steel 431 powder can be used across industries like automotive, aerospace, medical, and more due to its versatile properties. This article provides a deep dive into stainless steel 431 powder composition, properties, processing, applications and more.

Composition of Stainless Steel 431 Powder

The composition of stainless steel 431 powder is as follows:

Element	Composition Range
Chromium	14-18%
Nickel	1-2.5%
Manganese	1% max
Silicon	1% max
Carbon	0.20% max
Sulfur	0.030% max
Phosphorus	0.040% max
Iron	Balance

The key alloying elements in 431 stainless steel powder are:

• Chromium: Provides corrosion and oxidation resistance as it forms a protective chromium oxide layer on the steel surface. The 14-18% chromium content offers good corrosion resistance.
• Nickel: Nickel enhances corrosion resistance, improves hardenability and tensile properties. The 1-2.5% nickel in 431 powder aids in increasing hardness through heat treatment.
• Aluminum: Aluminum is added up to 1.25% to attain optimum hardness through heat treatment by facilitating precipitate formation.

The controlled low carbon content along with alloying additions of chromium, nickel and aluminum result in the unique properties of 431 stainless steel powder for high performance parts.

Properties

431 stainless steel powder offers the following physical, mechanical, thermal and chemical properties:

Physical Properties

Property	SS 431 Powder
Density	7.7 g/cm3
Melting Point	1400-1450°C
Particle size	Typically 10-45 microns
Flow rate	Good flowability

Mechanical Properties

Condition: Annealed at 815°C

Property	SS 431 Powder
Tensile Strength	485-655 MPa
Yield Strength	≥ 275 MPa
Elongation	12%
Hardness	92 HRB

Condition: Hardened at 1038°C, Air Cooled and Tempered at 371°C

Property	SS 431 Powder
Tensile Strength	1300-1800 MPa
Yield Strength	1280 MPa
Elongation	8%
Hardness	44-47 HRC

Thermal Properties

Property	SS 431 Powder
Coefficient of Thermal Expansion	9-11 x 10<sup>-6</sup> /K
Melting Range	1400-1450°C
Thermal Conductivity	24-35 W/m.K

Corrosion Resistance

Excellent resistance to:

• Atmospheric corrosion
• Water and Aqueous Solutions
• Organic Acids
• Sulfur Compounds
• Mild Oxidation and Reduction Environments

Moderate resistance to concentrated nitric acid

Production Methods

Stainless steel 431 powder can be produced through processes like gas atomization, rotary atomization and water atomization.

Gas Atomization

Inert gas like argon or nitrogen is used to atomize the molten metal into fine droplets that solidify into powder particles. Gas atomized stainless steel 431 powder has smooth particle morphology.

Water Atomization

High pressure water jets hit the metal stream and create fine droplets that turn into powder particles on rapid solidification. The powder particle shape is more irregular in water atomization.

Rotary Atomization

A rotating disk is used to centrifugally atomize the molten 431 stainless steel into fine droplets and powder. Particle sizes are slightly higher ranging 25-150 microns.

Microstructure and powder characteristics like flow, density, particle shape and size distribution can be controlled by process parameters in atomization. High purity inert gas, precise temperature control, protective environment and specialized atomization equipment ensure quality 431 stainless steel powder production.

Powder Processing

431 stainless steel powder undergoes a series of steps like degassing, conditioning, mixing and granulation before compacting and sintering to make net shape components.

Degassing: Removes dissolved gases like oxygen to prevent porosity

Conditioning: Powder characteristics like morphology and flow are enhanced through treatments

Mixing: Required composition is achieved by mixing elemental powders

Granulation: Coarse and fine powder particles are granulated for good flow rates

Compacting: Powder is compacted into desired component shapes

Sintering: Heat treatment for bonding powder particles into dense components

Powder size distribution and shape significantly influence the processing behavior. Gas atomized stainless steel 431 powder with particle sizes of 10-45 microns offers optimum properties for processing through metal injection molding where fine complex shaped components are fabricated.

Applications

The applications of stainless steel 431 powder spans across sectors like:

Automotive

• Gears
• Pistons
• Piston rings
• Valves
• Fluid handling parts

Aerospace and Defense

• Turbine components
• Landing gear parts
• Airframe components

Medical

• Surgical instruments
• Implants

Energy

• Nuclear reactor internals
• Steam/gas turbine parts

Chemical Industry

• Valves
• Pumps
• Fluid contact parts

Consumer

• Sporting equipment

The excellent combination of high strength, hardness, wear resistance and corrosion resistance allows stainless steel 431 powder to substitute traditional wrought alloys across these critical application areas.

Net shape precision components with intricate profiles can be manufactured through powder metallurgy techniques like metal injection molding using stainless steel 431 powder as feedstock. This allows lightweight, sustainable parts fabrication.

Comparative Properties

Stainless steel 431 powder stands out in comparison to other popular stainless steel grades:

Property	SS 431	SS 316L	SS 17-4PH	SS 420
Strength	Very High	Medium	Very High	Very High
Hardness	High	Medium	High	Very High
Corrosion Resistance	High	Very High	Medium	Medium
Wear Resistance	High	Medium	Medium	Medium
Heat Resistance	Excellent	Excellent	Excellent	Fair
Machinability	Difficult	Easy	Difficult	Difficult
Cost	Medium	High	High	Low

The high chromium martensitic SS 431 powder provides strength levels similar to precipitation hardening stainless steels. Matching properties at lower alloy costs make 431 stainless an attractive alternative for high performance parts production across industry verticals.

Standards and Certification

Stainless steel 431 powder composition, manufacture and testing adheres to the following standards:

• ASTM A240
• ASTM B299
• AMS 5643
• AMS 5752
• ASTM A276

Reputable 431 stainless steel powder manufacturers and metal powder suppliers have quality management certifications like ISO 9001, IATF 16949, ISO 13485, AS9100D indicating strict international production, inspection and testing standards compliance.

Suppliers and Pricing

Stainless steel 431 powder is available from leading metal powder producers:

Manufacturer	Powder Grade Available	Particle Size	Price Range
Sandvik	Osprey 431	10-45 microns	$25-30/Kg
Hoganas	Amperit 431	20-63 microns	$22-28/Kg
CNPC Powder	431SS	15-45 microns	$20-25/Kg
Carpenter	Custom 431	10-150 microns	$30-40/Kg

Custom particle size distributions and close powder compositions matching application requirements can be sourced from these global stainless steel powder manufacturers at competitive pricing.

FAQs

Q1: What is Stainless Steel 431 Powder?

A1: Stainless Steel 431 Powder is a powdered form of stainless steel alloy 431. It is typically used in additive manufacturing processes like powder metallurgy, 3D printing, and metal injection molding to create complex parts and components.

Q2: What is Stainless Steel 431 alloy?

A2: Stainless Steel 431 is a martensitic stainless steel known for its corrosion resistance and high strength. It contains a significant amount of chromium and nickel, which make it suitable for various applications.

Q3: What are the advantages of using Stainless Steel 431 Powder?

A3: Some advantages of using Stainless Steel 431 Powder include excellent corrosion resistance, high strength and hardness, and the ability to be used in high-temperature environments.

Q4: What are the applications of Stainless Steel 431 Powder?

A4: Stainless Steel 431 Powder is used in a wide range of applications, including aerospace, automotive, medical devices, oil and gas, and tooling due to its combination of strength, corrosion resistance, and heat resistance.

Q5: Can Stainless Steel 431 Powder be used for 3D printing?

A5: Yes, Stainless Steel 431 Powder can be used in certain 3D printing techniques like selective laser melting (SLM) or binder jetting to create intricate metal parts and prototypes.

know more 3D printing processes