Wrought magnesium alloy having improved properties, method of manufacturing same, and high-speed extrusion method using same

Patent metadata

Field	Value
Publication number	US-11692247-B2
Application number	US-202117215605-A
Country	US
Kind code	B2
Filing date	Mar 29, 2021
Priority date	Mar 30, 2020
Publication date	Jul 4, 2023
Grant date	Jul 4, 2023

Abstract

This application relates to a wrought magnesium alloy and a method of manufacturing the same, and a high-speed extrusion method for manufacturing an extrudate using the same. In one aspect, the magnesium alloy includes 2.0 wt % to 8.0 wt % of bismuth (Bi), 0.5 wt % to 6.5 wt % aluminum (Al), the balance of magnesium (Mg), and inevitable impurities. Using a magnesium alloy for high-speed extrusion according to the present disclosure, it is possible to manufacture a magnesium alloy extrudate having a good surface quality without hot cracking even under high-temperature (extrusion temperature: 300° C. to 450° C.) and high-speed (die-exit speed: 40 m/min to 80 m/min) extrusion conditions. Furthermore, the extrudate manufactured from the magnesium alloy exhibits greatly improved strength and elongation compared to existing magnesium extrudates even when the alloy does not contain a rare-earth metal.

First claim

What is claimed is:

1. A magnesium alloy, comprising:
5.0 wt % of bismuth (Bi);
6.0 wt % to 6.5 wt % aluminum (Al);
a balance of magnesium (Mg); and
inevitable impurities,
wherein a value of ultimate tensile strength (UTS)×tensile elongation of the magnesium alloy is 5792 MPa ·%.

2. The magnesium alloy of claim 1 , wherein a rare-earth metal is not contained as an alloying element.

3. The magnesium alloy of claim 1 , wherein high-speed extrusion is possible, the high-speed extrusion comprising a die-exit speed of 40 m/min or more.

4. The magnesium alloy of claim 1 , further comprising 0.1 wt % to 1.0 wt % of at least one metal selected from the group consisting of calcium (Ca), manganese (Mn), and yttrium (Y).

5. A method of manufacturing a magnesium alloy extrudate, comprising:
manufacturing a magnesium alloy billet by casting a melt of a magnesium alloy comprising 5.0 wt % of bismuth (Bi), 6.0 to 6.5 wt % of aluminum (Al), a balance of magnesium (Mg), and inevitable impurities;
subjecting the manufactured magnesium alloy billet to homogenization heat treatment and cooling; and
extruding the subjected magnesium alloy billet,
wherein a value of ultimate tensile strength (UTS)×tensile elongation of the magnesium alloy extrudate is 5792 MPa·%.

6. The method of claim 5 , wherein the magnesium alloy billet is subjected to homogenization heat treatment and subsequently water quenching.

7. The method of claim 5 , wherein a Mg 3 Bi 2 secondary phase is dynamically precipitated during the extruding.

8. The method of claim 5 , wherein the magnesium alloy billet is extruded using an indirect extrusion process, a direct extrusion process, a hydrostatic extrusion process, or an impact extrusion process.

9. The method of claim 5 , wherein the extruding is performed at an extrusion temperature of 300° C. to 450° C. and a die-exit speed of 40 m/min to 80 m/min.

10. The method of claim 9 , wherein the magnesium alloy billet is subjected to homogenization heat treatment at a temperature corresponding to a two-phase region of α-Mg and Mg 3 Bi 2 in an Mg—Bi—Al ternary equilibrium phase diagram.

11. A magnesium alloy extrudate manufactured using the method of claim 5 .

12. The magnesium alloy extrudate of claim 11 , further comprising Mg 3 Bi 2 precipitated particles as a secondary phase.

13. The magnesium alloy extrudate of claim 11 , wherein the aluminum (Al) is included in an amount of 6.0 wt %.

Assignees

• Kyungpook Nat Univ Ind Academic Coop Found

Inventors

• Park Sung Hyuk
• Go Jong Bin
• Jin Sang Cheol

Classifications

• C22C23/02 Primary

  with aluminium as the next major constituent · CPC title

• B22D21/04

  Casting aluminium or magnesium {(no material; see B22D21/007)} · CPC title

• B21C23/01

  starting from material of particular form or shape, e.g. mechanically pre-treated (B21C23/22 takes precedence) · CPC title

• C21D9/0081

  for slabs; for billets · CPC title

• B21C23/002

  Extruding materials of special alloys so far as the composition of the alloy requires or permits special extruding methods of sequences · CPC title