How To Make Stainless Steel Powder

To make stainless steel powder, the primary industrial method is Atomization, which involves melting stainless steel alloy (such as 316L or 17-4PH) and disintegrating the molten stream into fine droplets using high-pressure gas or water jets. These droplets rapidly solidify into powder particles, which are then screened for specific applications like 3D printing or MIM. Besides atomization, other specialized methods include the Plasma Rotating Electrode Process (PREP) for high-purity spherical powders and Solid-State Reduction for cost-effective sponge powders.

1. Core Process Of Atomization

In the current industrial environment, atomization is the most common and mature technology for producing high-quality stainless steel powder. The reason why everyone loves to use it is because it has excellent control over the particle size and shape of the powder, which can meet the needs of most high-end manufacturing.

Alloy smelting:

The first step is to melt high-grade stainless steel scrap or virgin raw materials in an induction furnace. The ones I deal with the most are usually these two:

• 316L: mainly because of its corrosion resistance.
• 17-4PH: If the customer has hard requirements for strength and hardness, this is definitely the right choice.

High pressure jet breaking:

After the alloy is melted, the liquid metal flows out through the tundish (Tundish), forming a controlled trickle of strands. At this time, the real “highlight” came-with a high-pressure medium to hit this metal flow:

• Gas atomization: An inert gas such as nitrogen or argon is used. The powder produced in this way has excellent sphericity and excellent fluidity, which is standard in the field of 3D printing.
• Water atomization: Replaced by high-pressure water jet. This method is low cost, but the shape of the output powder is usually irregular (even with points needle-like). To tell the truth, although it is a little less liquid, but in the traditional powder metallurgy press molding, this irregular shape is more likely to “bite” each other “.

Coagulation and collection:

The metal droplets solidify rapidly as they fall in the cooling chamber. The cooling rate directly determines the microstructure of the powder, which will show obvious differences in the later heat treatment.

2. Special Production Methods

Although the atomization method dominates the market, some specific industries have “cleanliness” for purity or structure, and some special means have to be moved out at this time.

Plasma Rotating Electrode Method (PREP):

If the client you serve is an aerospace or medical implant giant, PREP is pretty much the only option.

• Operating logic: stainless steel bar stock is made into an electrode and rotated at high speed while melting its end with a plasma gun.
• The result: centrifugal force will throw the molten metal out, forming extremely clean, perfectly spherical particles. The most important point is that this powder has almost no “satellite powder” (small particles attached to the main particles) and is extremely pure.

Solid-State Reduction:

Consider this approach when your project budget is very tight and you need the powder to have a “spongy” structure.

• Operating logic: stainless steel oxides or rolled steel scales are treated with a reducing agent at temperatures below the melting point.
• Result: 1 porous sponge powder was produced. Although it is rarely used in structural parts, this porosity is an advantage in friction materials and certain chemical applications.

3. Post-Processing

The powder doesn’t mean the job is done. No matter which method is used to make the original powder, it must be strictly screened, otherwise it cannot meet the industrial standards.

Particle size distribution (PSD) control:

We will use ultrasonic sieve or vibrating sieve, the powder according to the particle size grade strictly cut.

Quality level:

This step is crucial. The consistency of the powder directly determines the density and mechanical properties of the final product. I often tell the scene that the screening is not good, and the parts sintered at the back are all waste products.

4. Key Application Of Stainless Steel Powder

The production method directly determines what the powder can do. Here is a simple correspondence:

• 3D printing (additive manufacturing): Aerosolized powder or PREP powder must be used. High fluidity and bulk density are hard indicators.
• Metal Injection Molding (MIM): Very fine powders (typically under 22 microns) are usually required to make small, complex precision parts in electronics or cars.
• Traditional powder metallurgy: more choice of water atomized powder or sponge powder, mainly used for pressing and sintering conventional structural parts, the main cost-effective.

Author : Martin

“I am a materials engineering specialist with over 14 years of experience in powder metallurgy and advanced manufacturing. My expertise lies in the industrial production of high-performance metal alloys, particularly in optimizing atomization processes for stainless steel powders.”