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US-12624427-B2 - 3D printed high carbon content steel and method of preparing the same

US12624427B2US 12624427 B2US12624427 B2US 12624427B2US-12624427-B2

Abstract

A 3D printed product of an iron based alloy having a narrow distribution of carbide areas is disclosed, as well as a method of preparing the product where the HIP and hardening is combined.

Inventors

  • BESTE ULRIK

Assignees

  • VBN COMPONENTS AB

Dates

Publication Date
20260512
Application Date
20200120
Priority Date
20190118

Claims (8)

  1. 1 . 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 1.4 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 μm 2 and wherein the average carbide area is less than 2 μm 2 ; and wherein the carbide area distribution has a difference between the d90 value and d10 value of not more than 1.90 μm 2 and/or has a d90 value of not more than 2.20 μm 2 ; wherein the oxygen content in the 3D-printed product is 30 ppm or less; and wherein the alloy has a toughness of at least 3.8 J and a hardness of at least 871 HV2 kg.
  2. 2 . The 3D-printed product according to claim 1 , wherein the carbon content is equal to or greater than 1.4 and equal to or less than 3.0 weight %.
  3. 3 . The 3D-printed product according to claim 1 , wherein the alloy further comprises: Tungsten: equal to or greater than 2 and equal to or less than 13 weight %, Molybdenum: equal to or greater than 1 and equal to or less than 10 weight %, Vanadium: equal to or greater than 3 and equal to or less than 8 weight %; and optionally Cobalt: equal to or greater than 9 and equal to or less than 18 weight %.
  4. 4 . The 3D-printed product according to claim 1 , wherein the alloy comprises: Carbon: equal to or greater than 1.4 and equal to or less than 3.0 weight %; Chromium: equal to or greater than 2.0 and equal to or less than 22.0 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 %; Iron: balance; and wherein the alloy comprises unavoidable trace amount of impurities.
  5. 5 . The 3D-printed product according to claim 1 , wherein the alloy comprises: Carbon: equal to or greater than 2.20 and equal to or less than 2.60 weight %, Tungsten: equal to or greater than 5 and equal to or less than 13 weight %, Chromium: equal to or greater than 3.5 and equal to or less than 4.5 weight %, Cobalt: equal to or greater than 9 and equal to or less than 18 weight %; Molybdenum: equal to or greater than 3 and equal to or less than 10 weight %; Vanadium: equal to or greater than 5 and equal to or less than 8 weight %; Iron: balance; and unavoidable trace amount of impurities; or wherein the iron based alloy comprises: Carbon: equal to or greater than 2.25 and equal to or less than 2.40 weight %, Tungsten: equal to or greater than 6 and equal to or less than 8 weight %, Chromium: equal to or greater than 3.5 and equal to or less than 4.5 weight % Cobalt: equal to or greater than 9 and equal to or less than 12 weight %; Molybdenum: equal to or greater than 5 and equal to or less than 8 weight %; Vanadium: equal to or greater than 5 and equal to or less than 8 weight %; Iron: balance; or wherein the iron based alloy comprises: Carbon: equal to or greater than 1.2 and equal to or less than 1.8 weight %, Chromium: equal to or greater than 3.5 and equal to or less than 4.5 weight % Tungsten: equal to or greater than 2.0 and equal to or less than 4.0 weight %, Vanadium: equal to or greater than 3 and equal to or less than 5 weight %; Molybdenum: equal to or greater than 1 and equal to or less than 4 weight %; Iron: balance; or wherein the iron based alloy comprises: Carbon: equal to or greater than 1.5 and equal to or less than 2.3 weight %; Chromium: equal to or greater than 17 and equal to or less than 22.0 weight %; Vanadium: equal to or greater than 3 and equal to or less than 5 weight %; Molybdenum: equal to or greater than 1 and equal to or less than 3 weight %; Iron: balance; or wherein the iron based alloy comprises: Carbon: equal to or greater than 1.0 and equal to or less than 1.20 weight %, Chromium: equal to or greater than 2.0 and equal to or less than 5.0 weight %; Molybdenum: equal to or greater than 7 and equal to or less than 10 weight %; Cobalt: equal to or greater than 7 and equal to or less than 9 weight %; Tungsten: equal to or greater than 1.0 and equal to or less than 3.0 weight %; Vanadium: equal to or greater than 1.0 and equal to or less than 3.0 weight %; Iron: balance.
  6. 6 . The 3D-printed product according to claim 1 , wherein the average carbide area is less than 1 μm 2 .
  7. 7 . The 3D-printed product according to claim 1 , wherein the maximum carbide area is 4 μm 2 or less.
  8. 8 . The product according to claim 1 , wherein the product is a milling cutter, a shaper cutter, a power skiving cutter, a drill, a milling tool, an extrusion head, a wire drawing die, a hot rolling roll or a gliding or roll bearing ring.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a National Stage of International Application No. PCT/SE2020/050047 filed Jan. 20, 2020, which claims benefit of Swedish Patent Application No. 1950064-4 filed Jan. 18, 2019 and Swedish Patent Application No. 1951174-0 filed Oct. 17, 2019, all of which are herein incorporated by reference in their entirety. FIELD OF THE INVENTION The present invention relates to 3D printed products of an iron based alloy with high hardness. The 3D printed products are hardened using a furnace in which the product obtained from 3D printing is treated during Hot Isostatic Pressure (HIP) and quenched. BACKGROUND Today, when producing Powder Metallurgy materials, there exists a number of different techniques. One of the major methods is PM-HIP; Powder Metallurgy Hot Isostatic Pressing. The technique is to atomise (granulate) a metal powder, putting this powder into a container, sealing this container, and expose the sealed container for HIP, for example according to the standard process, at 1120-1150° C., at 100 MPa in typically 3 hours. The result is a consolidated material block which typically needs to be further processed. The container can be of different shapes, highly dependent on the material and the shape needed for the final part. It can also be a standard cylinder shape, if the material is going to become a bar for further production. In the latter case, for example for production of PM-HSS (powder metallurgy high speed steels) the material block is then typically forged and rolled to final bar dimensions. These bars are then typically soft annealed and then transported to a stock. Later on, they are transported to a workshop where the soft machining is done, for shape of the wanted detail such as a gear hob. However, after the soft machining, the gear hob blanks are hardened in a vacuum furnace and then tempered in another furnace. And finally, the hardened blanks could be ground to achieve the wanted tolerance of the surfaces. Typically, after machining of a soft annealed steel bar, hardening of the material is performed. One of the most common hardening process for PM-HSS is heating up to 1180° C., remain at that temperature for a hold time, and then quench down to 25-50° C. and assuring that the cooling rate minimum is 7° C./s between 1000° C. and 800° C. The hardening is then followed by tempering, where the material is repeatedly heated up to 560° C. with >1 h hold time, and then cooled to <25° C. between the repetitions. The temperatures are, of course, dependent of type of alloy and the goal for hardness. In addition, a stress revealing step (typically 600-700° C. in 2 h plus slow cooling to 500° C. and then cool down to 25° C.) can be added if heavy soft machining has been done. The result of the PM-HIP process is, beyond the powder quality, composition, forging and rolling, therefore an effect of temperature, pressure and time. HIP process can also be utilized on 3D-printed (additive manufactured) metal alloys. The process can then act as a way to close eventual pores from the 3D-printing process. The process will then act to ensure a full density component. After a HIP process of a 3D-printed product, a traditional hardening process can then be used. The result of 3D-printing, HIP and hardening process is then, in addition to powder quality, composition and 3D-printing parameters, also a result of temperature, pressure and time. Still this multiple step process is time consuming. SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawback of prior art. Therefore the present invention provides a method where HIP and hardening are combined and unexpectedly the obtained material had improved mechanical properties in comparison with the traditionally HIP and hardened material. The present invention also aims at providing materials or products having a more homogenous carbide size or carbide area distribution. For example the hardness of the material was improved with up to 12% and the abrasion study revealed a 7.5% lower wear rate. Additionally even though the hardness increased the toughness remained as for traditionally treated samples. This is more pronounced for alloys with higher carbon contents. In a first aspect the present invention relates to a 3D printed product according to claim 1. In a preferred embodiment the present invention relates to 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 comprisesCarbon: 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 9 and equal to or less than 18 weight %,Molybdenum: equal to or greater than 1 and eq