Sintering of Steel – 6 Use Cases

Making low nickel austenitic steel by sintering

A low nickel austenitic stainless steel powder is made with 10.5-30.0% Cr, 0.5-9.0% Ni, 0.01-2.0% Mn, 0.01-3.0% Sn, 0.1-3.0% Si, and max 0.5% of unavoidable impurities such as carbon and oxygen, with the rest being iron. The powder can be mixed with a lubricant but it’s not mandatory.

In the low nickel steel, other alloying elements, such as Cu, Mo, Cr, Ni, C, and hard phase materials are added for modification of dimensional changes and material properties.

The low nickel high grade austenitic steel can then be manufactured by compaction followed by sintering the iron-based powder composition. Compaction is done between 400 and 2000 MPa. Sintering is done in a nitrogen-oxygen atmosphere above 1000℃. Lastly, the sintered component is annealed above 1000℃ for improving its mechanical properties.

Refer to this patent for more information.

Anti-corrosion sintered coatings for steel

An anti-corrosion coating for steel can be made by preparing a slurry of silica, flux (e.g. sodium metasilicate nonahydrate and borax), calcium fluoride, thickener, and adhesion agent (e.g. manganese dioxide) followed by baking and sintering.

The coating process includes:

  1. The mixture is placed in a container, stirred, and then placed in a mixing machine to mix thoroughly.
  2. Water is added to the mixture at a weight ratio of (2-5):1.
  3. The steel rebars are coated with the slurry such that the rebars are immersed in, rotated, and pulled out from the slurry coating.
  4. The coated rebars are baked at 90-130℃ for 20-40 minutes.
  5. Sintering of the baked steel rebars is done using a furnace with a heating rate of 3-10 ℃/minute to 400-550℃ and maintained at that temperature for 10 minutes.
  6. Finally, the sintered steel rebars are cooled at room temperature.

Refer to this patent for more information.

Magnesium steel composites manufacturing by sintering

Magnesium-based composite steel fabrication system has a closed heating furnace, a pulse current loading system, an ultrasonic load applying system, a pressure and lifting system and a sealed insulating tube. Sintering and alloying of the metal matrix composite are carried out simultaneously.

Pulse current flows through materials to induce interface resistance heat and plasma discharge heat, thus increasing the heating speed of the sintering and reducing the radiant heat.

The coupling effect of the pulse electric field, the ultrasonic field and the pressure field is used to break the surface oxide film and realize sintering under atmospheric conditions by reducing atomic diffusion activation energy and promoting interface metallurgical reaction.

This process provides control over the morphology and the size of particles.

Refer to this patent for more information.

Carbon fibre reinforced sintered steel

A carbon-fiber-reinforced steel can be made of a continuous matrix of sintered steel nanoparticles and carbon fiber encapsulated within the steel matrix.

The reinforcing carbon fiber is formed of fibers having an average cross-sectional diameter less than about 5 mm.

The reinforcing carbon fiber can penetrate the continuous steel matrix to a penetration depth of at least 1 cm.

The ratio of penetration depth to fiber diameter of the reinforcing carbon fiber can be about 200:1 or greater.

Refer to this patent for more information.

Making light weight steel composite by sintering

A light weight steel composite material can be made of a continuous matrix of sintered steel nanoparticles and structural polymer that is fully encapsulated within the steel matrix.

The structural polymer can either be p-aramid, m-aramid or o-aramid. The composite material thus made has density less than 7g/cm3.

Refer to this patent for more information.

Sintered flux for ocean engineering steel

A sintered flux for ocean engineering steel can be prepared by mixing magnesium oxide and calcium fluoride in equal parts by weight, followed by further mixing aluminum fluoride, silicon, calcium, barium, sodium fluoride, zirconium and iron oxide in equal parts by weight.

This mixture is then mixed with waterglass. For better arc stability, the mixture should be heated and sintered to about 700°C.

The sintered flux can weld ocean engineering high-strength steel with yield strength of 550 MPa or higher. The sintered flux also has good arc stability, nice-looking weld beads and low hydrogen diffusibility.

Refer to this patent for more information.

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