Combined processing method for preparing anti-corrosion AZ91D magnesium alloy with obdurability

A combined processing and magnesium alloy technology, applied in the field of alloy processing, can solve problems such as poor corrosion resistance, and achieve the effect of improving the film forming process, improving the compactness and solving the poor corrosion resistance.

Inactive Publication Date: 2012-07-11
HOHAI UNIV +1
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Problems solved by technology

[0011] The object of the present invention is to provide a combined processing method for preparing strong, tough and corrosion-resistant AZ91D magnesium alloy with simple process operation and equipment requirements, thereby improving the strength and toughness of the alloy without changing the shape and size of the test piece, and solving its corrosion resistance The problem of poor performance, improve its yield

Method used

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  • Combined processing method for preparing anti-corrosion AZ91D magnesium alloy with obdurability
  • Combined processing method for preparing anti-corrosion AZ91D magnesium alloy with obdurability
  • Combined processing method for preparing anti-corrosion AZ91D magnesium alloy with obdurability

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] The as-cast Mg-9.05wt.%Al-0.65wt.%Zn alloy is processed by wire cutting into a columnar specimen of 19.5mm×19.5mm×40mm. The as-cast structure is mainly composed of α (Mg) matrix and dendrites. Reticulated Mg 17 Al 12 (β) phase composition (see figure 1 (a)). Among them, the β phase exists in two forms, one is the coarse bulk β phase, and the other is the fine lamellar β phase in the (α+β) eutectic structure. Perform surface pretreatment on the cut test piece, and then put it in a mold and heat it to 250°C for 10 minutes in the furnace, and then apply pressure for 16 consecutive passes of ECAP extrusion. The sample rotates 180° between adjacent passes (That is, the traditional C path) to improve the uniformity of the extrusion structure, the alloy structure is significantly refined after processing (see figure 1 (b)). After 16 passes of ECAP processing for Mg-9.05wt.%Al-0.65wt.%Zn alloy, the yield strength and tensile strength of the Mg-9.05wt.%Al-0.65wt.%Zn alloy are gr...

Embodiment 2

[0039] The as-cast Mg-9.05wt.%Al-0.65wt.%Zn alloy is processed by wire cutting into a columnar specimen of 19.5mm×19.5mm×40mm. The as-cast structure is mainly composed of α (Mg) matrix and dendrites. Reticulated Mg 17 Al 12 (β) phase composition (see figure 1 ). Among them, the β phase exists in two forms, one is the coarse bulk β phase, and the other is the fine lamellar β phase in the (α+β) eutectic structure. The cut test piece is subjected to surface pretreatment, and then placed in a mold and heated to 250°C for 10 minutes in the furnace, and then pressure is applied for 12 consecutive passes of ECAP extrusion. The specimen is rotated 180° between adjacent passes (That is, the traditional C path) to improve the uniformity of the extrusion structure, the alloy structure is significantly refined after processing (see Figure 8 ). After the Mg-9.05wt.%Al-0.65wt.%Zn alloy is processed by ECAP for 12 passes, the yield strength is 133.43MPa and the tensile strength is 230.52MPa...

Embodiment 3

[0041] The as-cast Mg-9.05wt.%Al-0.65wt.%Zn alloy is processed by wire cutting into a columnar specimen of 19.5mm×19.5mm×40mm. The as-cast structure is mainly composed of α (Mg) matrix and dendrites. Reticulated Mg 17 Al 12 (β) phase composition (see figure 1 ). Among them, the β phase exists in two forms, one is the coarse bulk β phase, and the other is the fine lamellar β phase in the (α+β) eutectic structure. The cut test piece is subjected to surface pretreatment, and then placed in a mold and heated to 250°C for 10 minutes in the furnace, and then pressure is applied for 8 consecutive ECAP extrusion passes, and the specimen is rotated 180° between adjacent extrusion passes (That is, the traditional C path) to improve the uniformity of the extrusion structure, the alloy structure is elongated after processing, and the grains are significantly refined (see Figure 13 ). After 8 passes of ECAP processing for the Mg-9.05wt.%Al-0.65wt.%Zn alloy, the yield strength is 150.5MPa,...

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Abstract

The invention discloses a combined processing method for preparing an anti-corrosion AZ91D magnesium alloy with obdurability. The combined processing method comprises the following steps: step 1, continuous ECAP (Equal Channel Angular Pressing), wherein the step 1 specifically comprises the substeps of: cutting a casting state AZ91D magnesium alloy blocky material into columnar test pieces, uniformly coating a solid lubricant on the surfaces of the test pieces after a regular pre-treatment and on a surface of a mould, putting the test pieces into the mould to be heated to 230 DEG C to 300 DEG C along with the furnace for heat preservation, then continuously performing ECAP deformation for multiple times, and rotating the test pieces for 180 DEG between two adjacent pressing passes to realize ultrafine processing of the alloy tissues; step 2, subsequent micro-arc oxidation surface treatment, wherein the step 2 specifically comprises the substeps of: cutting the test pieces obtained in the step 1 to obtain a shape needed by a member, performing the micro-arc oxidization treatment after grinding, polishing and ultrasonically cleaning the surfaces of the test pieces, putting the test pieces into silicate electrolyte, performing the micro-arc oxidization treatment for 15-20 min under the conditions that an externally applied voltage is 350-400 V, a duty ratio is 15-30% and a frequency of 400-600 Hz to finally obtain the anti-corrosion AZ91D magnesium alloy blocky material with excellent obdurability and corrosion resistance. The combined processing method for preparing the anti-corrosion AZ91D magnesium alloy with obdurability, disclosed by the invention, has the advantages of high yield, simple technological operation as well as equipment requirements and good industrial application prospect.

Description

1. Technical Field [0001] The invention relates to a combined processing method that uses equal channel angular extrusion and subsequent micro-arc oxidation surface treatment to improve the structure and surface state of an AZ91D magnesium alloy to improve its strength, toughness and corrosion resistance, and belongs to the technical field of alloy processing. 2. Background technology [0002] Although AZ91D magnesium alloy has better specific strength, specific rigidity and machinability, it is a close packed hexagonal structure (HCP), with low strength and poor plasticity. In addition, magnesium alloys mainly contain magnesium. The standard electrode potential of magnesium is -2.37V, which is the most negative electrode potential in metal structural materials. At the same time, the PB ratio of the oxide film (MgO) formed on the surface of the magnesium alloy in the air is less than 1, Can not play a stable and effective protective effect on the matrix, so magnesium alloys are p...

Claims

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Application Information

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IPC IPC(8): C22F1/06C25D11/30
Inventor 马爱斌周祺江静华宋丹
Owner HOHAI UNIV
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