Preparation method of high-strength and high-toughness A356.2 metal matrix composites for hub

Abstract

A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub is provided, including the following preparation process steps: preparation of a (graphene+HfB.sub.2)-aluminum master alloy wire; A356.2 alloy melting, master alloy addition, refining, and pressure casting; solution and aging treatment; shot blasting, finishing, alkaline/acid cleaning, anodic oxidation, and finished product packaging. In this way, two systems of two-dimensional nano-structure graphene nucleation and in-situ self-nucleation are introduced to complement each other, a second phase of silicon in A356.2 is refined by multi-dimensional scaling, and multi-dimensional nano-phases strengthen the aluminum-based composite material simultaneously. The preparation method solves the problems of limiting the strength, hardness, plasticity and toughness during the application of common A356.2 alloys for a hub, and a graphene/HfB.sub.2/aluminum composite material produced by a low-pressure casting process has an excellent comprehensive performance, so as to achieve a further weight reduction requirement for light weight.

Claims

1. A preparation method of a A356.2 metal matrix composite for a hub, comprising the following steps: step (1) charging an aluminum ingot into a resistance furnace after a temperature of the resistance furnace is increased to 420° C.; step (2) completely melting the aluminum alloy ingot, increasing the temperature to 720-740° C., adding an Al-20Si master alloy, and holding the temperature of a resulting melt at 720-740° C.; step (3) adding a magnesium ingot into a liquid surface of the melt, performing an electromagnetic stirring until the melt is homogenized, and adding 2-4 kg/ton of chlorine salt and fluorine salt refining agents under an argon atmosphere for refining at a refining temperature of 720-740° C.; step (4) adding an aluminum-graphene-hafnium diboride master alloy after statically holding the temperature for 5 min, and performing a slag-off treatment and a furnace discharging, wherein a content of graphene is 1-5% of a content of aluminum in the aluminum-graphene-hafnium diboride master alloy, a content of hafnium diboride is 0.3-1% of the content of aluminum in the aluminum-graphene-hafnium diboride master alloy, and a preparation method of the aluminum-graphene-hafnium diboride master alloy in the step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 740-760° C., then adding an aluminum-5% boron master alloy and an aluminum-10% graphene master alloy, and continuously casting and continuously rolling to produce an aluminum-graphene-hafnium diboride master alloy wire with a diameter of 9.5 mm; step (5) performing a pressure casting at a temperature of 690-720° C.; step (6) performing a solution and aging heat treatment process; step (7) performing a shot blasting, a mechanical finishing, an alkaline cleaning, an acid cleaning, a surface anodic oxidation, and a finished product packaging, wherein the A356.2 metal matrix composite for the hub is composed of the following alloy in mass percentage: 6.5-7.5% of Si, 0.30-0.45% of Mg, 0.04-0.08% of Cu, 0.03-0.15% of graphene, 0.01-0.05% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

2. The preparation method according to claim 1, wherein graphene in the step (4) is 1-5 layers of graphene with a particle size of 1-15 μm.

3. The preparation method according to claim 1, wherein in the step (5), a pressure in the pressure casting is divided into a boost pressure and a mold-filling pressure, the boost pressure is 0.3-0.6 kPa, a boost time is 2-5 s, the mold-filling pressure is 10-20 kPa, a mold-filling time is 5-10 s, a mold-holding time is 200-400 s, and a casting mold temperature during the pressure casting is 260-360° C.

4. The preparation method according to claim 1, wherein in the step (6), specific operations of the solution and aging heat treatment process are: performing a solution at a temperature of 535° C. for 4-6 h, performing a water quenching at a temperature of 40-60° C. for 3-5 min, performing an aging at a temperature of 170-190° C., holding the temperature in the aging for 4-8 h, and performing an air cooling.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGURE is a scanning electron micrograph showing an effect of addition of graphene/HfB.sub.2 on refinement of an alloy silicon phase, where (A) and (B) of FIGURE are scanning electron micrographs of an A356.2 metal matrix composites not added with graphene/HfB.sub.2, and (C) and (D) of FIGURE are scanning electron micrographs of an A356.2 alloy added with graphene/HfB.sub.2.

DESCRIPTION OF THE EMBODIMENTS

(2) Embodiments of the present disclosure are described in detail below. The embodiments are implemented on the premise of the technical solution of the present disclosure. Detailed implementations and specific operation processes are given. However, the protection scope of the present disclosure is not limited to the following embodiments.

(3) Not more than 0.1% of Ti, not more than 0.1% of Fe and not more than 0.05% of Mn refer to the content of allowable impurities in a composite material.

Embodiment 1

(4) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.2% of Si, 0.38% of Mg, 0.06% of Cu, 0.15% of graphene, 0.01% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(5) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(6) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(7) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 720° C., and the temperature of a melt is held.

(8) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 3 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at 720° C.

(9) (4) An aluminum-graphene-hafnium diboride master alloy is added after statically holding the temperature for 5 min, and slag-off treatment and furnace discharging are performed. The content of graphene is 5% of that of aluminum in the master alloy, and the content of hafnium diboride is 0.3% of that of aluminum in the master alloy.

(10) (5) Low-pressure casting is performed at 700° C. A boost pressure is 0.5 kPa, a boost time is 5 s, a mold-filling pressure is 18 kPa, a mold-filling time is 8 s, a mold-holding time is 400 s, and a casting mold temperature during casting is 260-360° C.

(11) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 5 h, performing water quenching at a temperature of 60° C. for 4 min, performing aging at a temperature of 180° C., holding the temperature for 8 h, and performing air cooling.

(12) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(13) A preparation method of the aluminum-graphene-hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 760° C., then adding an aluminum-5% boron master alloy and an aluminum-10% graphene master alloy, and continuously casting and continuously rolling to produce a master alloy wire with a diameter of 9.5 mm. Graphene is 1-3 layers of graphene with a particle size of 1 μm.

Embodiment 2

(14) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 6.5% of Si, 0.30% of Mg, 0.04% of Cu, 0.03% of graphene, 0.01% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(15) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(16) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(17) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 740° C., and the temperature of a melt is held.

(18) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 2 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 730° C.

(19) (4) An aluminum-graphene-hafnium diboride master alloy is added after statically holding the temperature for 5 min, and slag-off treatment and furnace discharging are performed. The content of graphene is 3% of that of aluminum in the master alloy, and the content of hafnium diboride is 1% of that of aluminum in the master alloy.

(20) (5) Low-pressure casting is performed at 690° C. A boost pressure is 0.4 kPa, a boost time is 3 s, a mold-filling pressure is 12 kPa, a mold-filling time is 10 s, a mold-holding time is 350 s, and a casting mold temperature is 320° C.

(21) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 5 h, performing water quenching at a temperature of 50° C. for 4 min, performing aging at a temperature of 170° C., holding the temperature for 6 h, and performing air cooling.

(22) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(23) A preparation method of the aluminum-graphene-hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 760° C., then adding an aluminum-5% boron master alloy and an aluminum-10% graphene master alloy, and continuously casting and continuously rolling to produce a master alloy wire with a diameter of 9.5 mm. Graphene is 5 layers of graphene with a particle size of 15 μm.

Embodiment 3

(24) A high-strength and high-toughness A356.2 aluminum-based composite material for a hub is composed of the following alloy in mass percentage: 7.5% of Si, 0.45% of Mg, 0.08% of Cu, 0.03% of graphene, 0.03% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(25) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(26) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(27) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 720° C., and the temperature of a melt is held.

(28) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 4 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 720° C.

(29) (4) An aluminum-graphene-hafnium diboride master alloy is added after statically holding the temperature for 5 min, and slag-off treatment and furnace discharging are performed. The content of graphene is 1% of that of aluminum in the master alloy, and the content of hafnium diboride is 1% of that of aluminum in the master alloy.

(30) (5) Low-pressure casting is performed at 690° C. A boost pressure is 0.3 kPa, a boost time is 2 s, a mold-filling pressure is 10 kPa, a mold-filling time is 5 s, a mold-holding time is 200 s, and a casting mold temperature is 360° C.

(31) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 6 h, performing water quenching at a temperature of 60° C. for 5 min, performing aging at a temperature of 190° C., holding the temperature for 4 h, and performing air cooling.

(32) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(33) A preparation method of the aluminum-graphene-hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 760° C., then adding an aluminum-5% boron master alloy and an aluminum-10% graphene master alloy, and continuously casting and continuously rolling to produce a master alloy wire with a diameter of 9.5 mm. Graphene is 5 layers of graphene with a particle size of 10 μm.

Embodiment 4

(34) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.06% of Cu, 0.07% of graphene, 0.02% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(35) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(36) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(37) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 730° C., and the temperature of a melt is held.

(38) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 4 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at 740° C.

(39) (4) An aluminum-graphene-hafnium diboride master alloy is added after statically holding the temperature for 5 min, and slag-off treatment and furnace discharging are performed. The content of graphene is 2.1% of that of aluminum in the master alloy, and the content of hafnium diboride is 0.6% of that of aluminum in the master alloy.

(40) (5) Low-pressure casting is performed at 710° C. A boost pressure is 0.5 kPa, a boost time is 5 s, a mold-filling pressure is 15 kPa, a mold-filling time is 8 s, a mold-holding time is 400 s, and a casting mold temperature is 260° C.

(41) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 4 h, performing water quenching at a temperature of 50° C. for 5 min, performing aging at a temperature of 180° C., holding the temperature for 4 h, and performing air cooling.

(42) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(43) A preparation method of the aluminum-graphene-hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 760° C., then adding an aluminum-5% boron master alloy and an aluminum-10% graphene master alloy, and continuously casting and continuously rolling to produce a master alloy wire with a diameter of 9.5 mm. Graphene is 5 layers of graphene with a particle size of 10 μm.

Comparative Example 1

(44) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.06% of Cu, 0.07% of graphene, 0.02% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(45) A preparation method of a high-strength and high-toughness A356.2 aluminum-based composite material for a hub includes the following steps.

(46) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(47) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 740° C., and the temperature of a melt is held.

(48) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 4 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 740° C.

(49) (4) After statically holding the temperature for 5 min, direct stirring is performed, and graphene powder with a particle size of 15 μm and HfB.sub.2 powder of 3 μm are added.

(50) (5) Low-pressure casting is performed at 710° C. A boost pressure is 0.5 kPa, a boost time is 2-5 s, a mold-filling pressure is 20 kPa, a mold-filling time is 10 s, a mold-holding time is 350 s, and a casting mold temperature is 300° C.

(51) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 4 h, performing water quenching at a temperature of 50° C. for 5 min, performing aging at a temperature of 180° C., holding the temperature for 4 h, and performing air cooling.

(52) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(53) Graphene is 5 layers of graphene with a particle size of 10 μm.

Comparative Example 2

(54) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.05% of Cu, 0.08% of graphene, 0.02% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(55) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(56) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(57) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 720° C., and the temperature of a melt is held.

(58) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 3 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 720° C.

(59) (4) After statically holding the temperature for 5 min, an aluminum-10% graphene master alloy and HfB.sub.2 powder with a particle size of 3 μm are added, and slag-off treatment and furnace discharging are performed.

(60) (5) Low-pressure casting is performed at 690° C. A boost pressure is 0.3 kPa, a boost time is 2 s, a mold-filling pressure is 15 kPa, a mold-filling time is 5 s, a mold-holding time is 200 s, and a casting mold temperature is 300° C.

(61) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 6 h, performing water quenching at a temperature of 60° C. for 5 min, performing aging at a temperature of 190° C., holding the temperature for 4 h, and performing air cooling.

(62) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(63) Graphene is 1-3 layers of graphene with a particle size of 12 μm.

Comparative Example 3

(64) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.02% of Cu, 0.10% of graphene, 0.02% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(65) A preparation method of a high-strength and high-toughness A356.2 metal matrix composites for a hub includes the following steps.

(66) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(67) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 740° C., and the temperature of a melt is held.

(68) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 4 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 730° C.

(69) (4) An aluminum-graphene-hafnium diboride master alloy is added after statically holding the temperature for 5 min, and slag-off treatment and furnace discharging are performed. The content of graphene is 5% of that of aluminum in the master alloy, and the content of hafnium diboride is 1% of that of aluminum in the master alloy.

(70) (5) Low-pressure casting is performed at 720° C. A boost pressure is 0.4 kPa, a boost time is 3 s, a mold-filling pressure is 12 kPa, a mold-filling time is 10 s, a mold-holding time is 350 s, and a casting mold temperature is 300° C.

(71) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 5 h, performing water quenching at a temperature of 50° C. for 4 min, performing aging at a temperature of 170° C., holding the temperature for 6 h, and performing air cooling.

(72) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(73) A preparation method of the aluminum-graphene-hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 760° C., and then blowing argon into graphene powder. Graphene is 1-3 layers of graphene with an average particle size of 5 μm.

Comparative Example 4

(74) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.2% of Si, 0.38% of Mg, 0.06% of Cu, 0.01% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al.

(75) A preparation method of a high-strength and high-toughness A356.2 aluminum-based composite material for a hub includes the following steps.

(76) (1) An aluminum ingot is charged into a resistance furnace when the temperature of the resistance furnace is increased to 420° C.

(77) (2) After the aluminum ingot is completely melted, an Al-20Si master alloy is added under the condition of increasing the temperature to 730° C., and the temperature of a melt is held.

(78) (3) A magnesium ingot is rapidly added below a liquid surface of the aluminum melt, and electromagnetically stirred until the melt is homogenized, and 4 kg/ton of chlorine salt and fluorine salt refining agents are added under an argon atmosphere for refining at a refining temperature of 720° C.

(79) (4) After statically holding the temperature for 5 min, an aluminum-1% hafnium diboride master alloy is added, and slag-off treatment and furnace discharging are performed.

(80) (5) Low-pressure casting is performed at 700° C. A boost pressure is 0.5 kPa, a boost time is 5 s, a mold-filling pressure is 18 kPa, a mold-filling time is 8 s, a mold-holding time is 400 s, and a casting mold temperature is 280° C.

(81) (6) A solution and aging heat treatment process is performed, including: performing solution at a temperature of 535° C. for 5 h, performing water quenching at a temperature of 60° C. for 4 min, performing aging at a temperature of 180° C., holding the temperature for 8 h, and performing air cooling.

(82) (7) Shot blasting, mechanical finishing, alkaline cleaning, acid cleaning, surface anodic oxidation, and finished product packaging are performed.

(83) A preparation method of the aluminum-1% hafnium diboride master alloy in step (4) is: adding an aluminum-10% hafnium master alloy into an aluminum melt of 750° C., and then adding an aluminum-5% boron master alloy. The particle size is 10 μm.

Comparative Example 5

(84) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.06% of Cu, 0.07% of graphene, 0.05% of HfB.sub.2, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al. The other methods are the same as in Embodiment 4.

Comparative Example 6

(85) A high-strength and high-toughness A356.2 metal matrix composites for a hub is composed of the following alloy in mass percentage: 7.0% of Si, 0.35% of Mg, 0.06% of Cu, 0.07% of graphene, not more than 0.1% of Ti, not more than 0.1% of Fe, not more than 0.05% of Mn, and the balance of Al. The other methods are the same as in Comparative Example 2, and no hafnium diboride is added in step (4).

(86) TABLE-US-00001 TABLE 1 Comparison of Mechanical Properties Heat Tensile Yield Treatment Strength Strength Elongation Material Process (MPa) (MPa) (%) Comparative 535° C./5 h 180 131 1.0% Example 1 180° C./4 h Comparative 535° C./5 h 317 234 4.0% Example 2 190° C./8 h Comparative 535° C./5 h 150 126 1.0% Example 3 170° C./6 h Comparative 535° C./6 h 287 209 3.5% Example 4 180° C./4 h Comparative 535° C./4 h 368 309 2.5% Example 5 180° C./4 h Comparative 535° C./4 h 305 280 2.1% Example 6 190° C./4 h Embodiment 1 535° C./5 h 320 243 5.0% 180° C./8 h Embodiment 2 535° C./6 h 342 298 5.5% 170° C./4 h Embodiment 3 535° C./6 h 365 314 6.5% 190° C./4 h Embodiment 4 535° C./4 h 386 325 7.0% 180° C./4 h

(87) It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit and scope of the present disclosure. Thus, if these modifications and variations of the present disclosure fall within the scope of the claims of the present disclosure and equivalent technologies, the present disclosure is also intended to include these modifications and variations.