3d printed high carbon content steel and method of preparing the same

A 3D-printed product made of an iron based alloy comprising a metal matrix and grains of carbides embedded in the metal matrix;

• wherein the alloy comprises
• Carbon:
• equal to or greater than 1.0 and equal to or less than 5.0 weight %;
• Chromium:
• equal to or greater than 2.0 and equal to or less than 22.0 weight %;
• Iron:
• balance;
• wherein the alloy further comprises at least two of the elements:
• Tungsten:
• equal to or greater than 2 and equal to or less than 13 weight %,
• Cobalt:
• equal to or greater than 7 and equal to or less than 18 weight %,
• Molybdenum:
• equal to or greater than 1 and equal to or less than 10 weight %, and
• Vanadium:
• equal to or greater than 3 and equal to or less than 8 weight %;
• and
• wherein the alloy comprises unavoidable trace amount of impurities;
• and
• wherein the maximum carbide area is less than 8 μm2 and wherein the average carbide area is less than 2 μm2;
• and/or
• wherein the carbide area distribution has a difference between the d90 value and d10 value of not more than 1.90 μm2;
• and/or
• wherein the carbide area distribution has a d90 value of not more than 2.20 m2.

A method of preparing a 3D-printed product comprising

• a. providing a powder of an iron based alloy wherein the iron based alloy further comprises carbon and unavoidable amounts of impurities;
• b. 3D printing a product from the iron based alloy in a free forming apparatus having a chamber wherein the 3D printing is performed in vacuum;
• and
• c. treating the obtained product in step b by
• i. placing the product in a furnace;
• ii. heating the product to a first temperature of at least 850° C., increasing the pressure in the furnace to a first pressure of at least 80 MPa and keeping the product at the first temperature and pressure during a first hold time;
• iii. heating the product to a second temperature of at least 950° C. and keeping the product at the second temperature and at a second pressure during a second hold time;
• iv. quenching the product to a third temperature and reducing the pressure in the furnace to a third pressure, and keeping the product at the third temperature and pressure for a third hold time;
• and
• v. performing a temperature cycle by heating the product to a fourth temperature and increasing the pressure in the furnace to a fourth pressure and keeping the product at the fourth temperature and pressure for a fourth hold time, followed by lowering the temperature of the product to a fifth temperature.