STAINLESS STEEL POWDER COMPOSITION, PREPARING METHOD THEREOF AND METHOD OF PREPARING STAINLESS STEEL WORKPIECE BY LASER ADDITIVE MANUFACTURING

Abstract

Provided is a stainless steel powder composition, which comprises Cr, Cu, Mn, Mo, Ni and Fe; wherein, based on a total weight of the stainless steel powder composition, a content of Cr is 20 wt% to 24 wt%, and a content of Cu is more than 0 wt% and less than or equal to 0.5 wt%, a content of Mn is more than 0 wt% and less than or equal to 2 wt%, a content of Mo is 2.25 wt% to 3 wt% and a content of Ni is 10 wt% to 15 wt%. When applying the stainless steel powder composition of the present invention to laser additive manufacturing (LAM), the produced stainless steel workpiece has enhanced tensile strength, thereby expanding the follow-up applications and increasing the commercial value.

Claims

1. A stainless steel powder composition, comprising chromium, copper, manganese, molybdenum, nickel and iron; wherein, based on a total weight of the stainless steel powder composition, a content of chromium is 20 weight percent to 24 weight percent, a content of copper is more than 0 weight percent and less than or equal to 0.5 weight percent, a content of manganese is more than 0 weight percent and less than or equal to 2 weight percent, a content of molybdenum is 2.25 weight percent to 3 weight percent and a content of nickel is 10 weight percent to 15 weight percent.

2. The stainless steel powder composition as claimed in claim 1, wherein based on the total weight of the stainless steel powder composition, the content of nickel is 11.5 weight percent to 13.5 weight percent.

3. The stainless steel powder composition as claimed in claim 1, wherein based on the total weight of the stainless steel powder composition, the content of chromium is 22 weight percent to 24 weight percent.

4. The stainless steel powder composition as claimed in claim 1, wherein based on the total weight of the stainless steel powder composition, a content of phosphorus contained in the stainless steel powder composition is less than or equal to 0.025 weight percent and a content of sulfur contained in the stainless steel powder composition is less than or equal to 0.03 weight percent.

5. The stainless steel powder composition as claimed in claim 2, wherein based on the total weight of the stainless steel powder composition, a content of phosphorus contained in the stainless steel powder composition is less than or equal to 0.025 weight percent and a content of sulfur contained in the stainless steel powder composition is less than or equal to 0.03 weight percent.

6. The stainless steel powder composition as claimed in claim 3, wherein based on the total weight of the stainless steel powder composition, a content of phosphorus contained in the stainless steel powder composition is less than or equal to 0.025 weight percent and a content of sulfur contained in the stainless steel powder composition is less than or equal to 0.03 weight percent.

7. A preparing method of a stainless steel powder composition, comprising the following steps: step (a): mixing a chromium raw material, a copper raw material, a manganese raw material, a molybdenum raw material, a nickel raw material and an iron raw material to obtain a mixture; wherein, based on a total weight of the mixture, a content of the chromium raw material is 20 weight percent to 24 weight percent, a content of the copper raw material is more than 0 weight percent and less than or equal to 0.5 weight percent, a content of the manganese raw material is more than 0 weight percent and less than or equal to 2 weight percent, a content of the molybdenum raw material is 2.25 weight percent to 3 weight percent and a content of the nickel raw material is 10 weight percent to 15 weight percent; and step (b): melting the mixture and then atomizing with an inert gas to obtain the stainless steel powder composition.

8. The preparing method as claimed in claim 7, wherein based on the total weight of the mixture, the content of the nickel raw material is 11.5 weight percent to 13.5 weight percent.

9. The preparing method as claimed in claim 7, wherein based on the total weight of the mixture, the content of the chromium raw material is 22 weight percent to 24 weight percent.

10. The preparing method as claimed in claim 7, wherein the purities of the chromium raw material, the copper raw material, the manganese raw material, the molybdenum raw material, the nickel raw material and the iron raw material are more than 99.5%.

11. The preparing method as claimed in claim 7, wherein in the step (b), an environmental pressure during the atomizing is 2.5×10.sup.-3 torr to 3.5×10.sup.-3 torr.

12. The preparing method as claimed in claim 8, wherein in the step (b), an environmental pressure during the atomizing is 2.5×10.sup.-3 torr to 3.5×10.sup.-3 torr.

13. The preparing method as claimed in claim 9, wherein in the step (b), an environmental pressure during the atomizing is 2.5×10.sup.-3 torr to 3.5×10.sup.-3 torr.

14. The preparing method as claimed in claim 10, wherein in the step (b), an environmental pressure during the atomizing is 2.5×10.sup.-3 torr to 3.5×10.sup.-3 torr.

15. A method of preparing a stainless steel workpiece, comprising adopting the stainless steel powder composition as claimed in claim 1 and preparing the stainless steel workpiece from the stainless steel powder composition by laser additive manufacturing.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Hereinafter, preparation methods of several embodiments are exemplified to illustrate the implementation of the present invention. One person skilled in the art can easily realize the advantages and effects of the present invention in accordance with the contents of the specification. Various modifications and variations could be made in order to practice or apply the present invention without departing from the spirit and scope of the invention.

Examples 1 to 3: Stainless Steel Powder Composition

[0043] According to the compositions and the contents listed in the following Table 1, Cr powder, Cu powder, Mn powder, Mo powder, Ni powder and Fe powder in suitable amounts were mixed to obtain a mixture; wherein, the purity of the Cr powder was 99.6%, the purity of the Cu powder was 99.81%, the purity of the Mn powder was 99.8%, the purity of the Mo powder was 99.8%, the purity of the Ni powder was 99.8% and the purity of the Fe powder was 99.7%.

[0044] Next, the mixture was placed at an environment with a temperature of 1700° C. and pressure of 3 10 x.sup.-3 torr, and then atomized with argon under gas ejection pressure of 25 bar to obtain the stainless steel powder compositions of Examples 1 to 3. In the following Table 1, the contents of Cr, Cu, Fe, Mn, Mo, Ni, P and Si of the stainless steel powder compositions of Examples 1 to 3 were measured and obtained by inductively coupled plasma optical emission spectrometer (ICP-OES; manufacturer: Agilent; model: 5110 ICP-OES); the contents of C and S thereof were measured and obtained by carbon/sulfur analyzer (manufacturer: HORIBA; model: EMIA 20P); and the content of O was measured and obtained by oxygen/nitrogen/hydrogen analyzer (manufacturer: HORIBA; model: EMGA 830).

Comparative Example 1: Stainless Steel Powder Composition

[0045] The preparing processes of Comparative Example 1 were similar to Examples 1 to 3, and the main difference was that Comparative Example 1 adopted different contents of components to prepare the mixture according to the following Table 1. Also, in Comparative Example 1, the purity of the Cr powder was 98.5%, the purity of the Cu powder was 99%, the purity of the Mn powder was 99%, the purity of the Mo powder was 98.5%, the purity of the Ni powder was 99% and the purity of the Fe powder was 99%. Except for the foresaid differences, the rest of the preparing processes were the same as Examples 1 to 3, so as to obtain the stainless steel powder composition of Comparative Example 1. In the following Table 1, the content of each component of the stainless steel powder composition of Comparative Example 1 was measured and obtained by the same ways as Examples 1 to 3.

TABLE-US-00001 The compositions and contents of the stainless steel powder compositions of Examples 1 to 3 and Comparative Example 1. Compositions Comparative Example 1 Example 1 Example 2 Example 3 Content of each component (wt%) Cr 18.18 22.58 22.03 22.34 Cu 0.095 0.250 0.226 0.280 Fe Balance Balance Balance Balance Mn 1.073 1.102 1.094 1.123 Mo 2.631 2.465 2.473 2.599 Ni 14.08 12.80 14.01 14.70 P 0.013 0.008 0.007 0.008 Si 0.346 0.272 0.291 0.257 C 0.022 0.007 0.012 0.011 S 0.004 0.001 0.002 0.002 O More than 0.05 Less than 0.05 Less than 0.05 Less than 0.05

Test Example 1: Evaluation of Tensile Strength

[0046] The stainless steel compositions of Examples 1 to 3 and Comparative Example 1 were adopted, and the tensile strength test was carried out according to the specifications of ASTM E8/E8M-16a test method. Specifically, the stainless steel powder compositions of Examples 1 to 3 and Comparative Example 1 were subjected to PBF to produce the same size of stainless steel samples of Examples 1 to 3 and Comparative Example 1. Then, the stainless steel samples of Examples 1 to 3 and Comparative Example 1 were each placed onto an universal testing machine (manufacturer: SHIMADZU; model: UH-F300KNXR) for the tensile strength test, and the results of tensile strength of Examples 1 to 3 and Comparative Example 1 were listed in the following Table 2.

TABLE-US-00002 The results of tensile strength of Examples 1 to 3 and Comparative Example 1. Groups Tensile strength (MPa) Example 1 735 Example 2 739 Example 3 792 Comparative Example 1 654

[0047] According to the results in the above Table 2, the tensile strength of Comparative Example 1 was only 654 MPa, while the tensile strength of Examples 1 to 3 were all higher than 700 MPa. Specifically, compared to Comparative Example 1, the tensile strength of Example 1 had increased by about 12%; the tensile strength of Example 2 had increased by about 13%; and the tensile strength of Example 3 had increased up to about 21%. Accordingly, Examples 1 to 3 had obviously higher tensile strength than Comparative Example 1. That is, by adopting the stainless steel powder composition of the present invention as raw material and then producing a stainless steel workpiece by LAM, the produced stainless steel workpiece actually had enhanced tensile strength.

[0048] In summary, as the present invention controls the content of each component of the stainless steel powder composition within a specific range, and then applying the stainless steel powder composition of the present invention to LAM, the produced stainless steel workpiece has enhanced tensile strength, thereby expanding the follow-up applications and increasing the commercial value.

[0049] Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.