CN104480361A

CN104480361A - High-strength/toughness heat-resistant die casting magnesium alloy and preparation method thereof

Info

Publication number: CN104480361A
Application number: CN201410686849.9A
Authority: CN
Inventors: 王峰; 孙士杰; 刘正; 毛萍莉; 王志
Original assignee: Shenyang University of Technology
Current assignee: Shenyang University of Technology
Priority date: 2014-11-26
Filing date: 2014-11-26
Publication date: 2015-04-01
Anticipated expiration: 2034-11-26
Also published as: CN104480361B

Abstract

The invention belongs to the field of metal materials. In order to improve the problems of lower strength/toughness and poor heat resistance in the existing commercial die casting magnesium alloy, metals Ca, Sn and Al are added into the AM60 alloy to develop a high-strength/toughness heat-resistant die casting magnesium alloy and a preparation method thereof. The magnesium alloy comprises the following components in percentage by mass: 6.5-8.0% of Al, 0.95-1.1% of Ca, 0.45-0.8% of Sn, 0.2-0.4% of Mn, at most 0.02% of Zn, at most 0.03% of impurity element, at most 0.01% of other impurities (Fe+Ni+Cu) and the balance of Mg. The alloy has the advantages of low cost, simple melt treatment, favorable die casting properties, high strength/toughness and high heat resistance, is easy to popularize and use, is especially suitable for large-scale commercial production, and has great market potential. The room-temperature and high-temperature mechanical properties of the alloy are respectively higher than those of commercial AZ91 and AM60 alloys.

Description

A kind of high-toughness heat-resistant diecast magnesium alloy and preparation method thereof

Technical field

The present invention mainly relates to a kind of high-toughness heat-resistant diecast magnesium alloy and preparation method thereof, belongs to metal material field.

Background technology

Magnesium alloy, as the lightest structural metallic materials, is widely used in the fields such as automobile, aviation and electronic equipment.Mg-Al system alloy is the diecast magnesium alloy be most widely used at present, but its obdurability is limited, and main strengthening phase Mg in Mg-Al system alloy ₁₇al ₁₂alligatoring and softening is easily there is when use temperature is more than 120 DEG C, cannot pinning crystal boundary and hinder the slippage of dislocation, cause alloy high-temp poor-performing, limit its range of application to a certain extent.At present, in conventional Mg-Al system alloy for die casting, although AZ91 magnesium alloy mobility and intensity are better, its plasticity is poor, and elongation is only 3%; And the intensity of plasticity good AM50 or AM60 alloy is lower; AE alloy and AS system are owing to having good resistance toheat containing rare earth and silicon, but its mobility is poor and cost is also higher, make it apply less.Therefore, develop the diecast magnesium alloy with good castability and mechanical property to have great importance to the application expanding magnesium alloy.

Summary of the invention

Goal of the invention:

The present invention is directed to the situation that mechanical property under the weak point, particularly high temperature of existing die casting AZ91, AM50 and AM60 magnesium alloy mechanical property is poor, a kind of high-toughness heat-resistant diecast magnesium alloy containing Ca and Sn and preparation method thereof is provided.By on the basis of AM60 alloy, add appropriate metal Ca, Sn and Al, improve the performance of alloy, make it that there is good room temperature obdurability and good resistance toheat, to meet the needs of industrial circle.

Technical scheme:

The present invention is achieved through the following technical solutions:

A kind of high-toughness heat-resistant diecast magnesium alloy, it is characterized in that: with industrial magnesium alloy AM60 ingot casting for mother alloy, add Ca, Sn and Al to make, it is characterized in that: the chemical constitution of this alloy is by mass percentage: 6.5 ~ 8.0%Al, 0.95 ~ 1.1%Ca, 0.45 ~ 0.8%Sn, 0.2 ~ 0.4%Mn, Zn≤0.02%, impurity element S i≤0.03%, other impurity (Fe+Ni+Cu)≤0.01%, surplus is Mg.

A preparation method for high-toughness heat-resistant diecast magnesium alloy described above, is characterized in that: the method step is as follows: select industrial magnesium alloy AM60 ingot casting to be mother alloy, master alloy ingot is preheated to 200 ~ 250 DEG C, and is having SF ₆and N ₂the melt in furnace of mixture gas shield; after mother alloy all melts; temperature is risen to 700 DEG C, by pure Al, directly add in melt after pure Ca and pure Sn preheating; through being uniformly mixed; continue to be warming up to 710 ~ 720 DEG C, leave standstill 20 ~ 30 minutes, be then cooled to 690 ~ 700 DEG C; take surface scum off, carry out die casting.

This Alloy At Room Temperature tensile strength is 260 ~ 280MPa, and yield strength is 170 ~ 185MPa, and elongation is that at 9 ~ 11%, 150 DEG C of temperature, tensile strength is 180 ~ 200MPa, and yield strength is 120 ~ 140MPa, and elongation is 15 ~ 19%.

Advantage and effect:

The present invention is a kind of high-toughness heat-resistant diecast magnesium alloy and preparation method thereof, and tool has the following advantages:

The magnesium alloy developed by mentioned component proportioning and preparation technology has good room temperature obdurability and resistance toheat, this Alloy At Room Temperature tensile strength is 260 ~ 280MPa, yield strength is 170 ~ 185MPa, elongation is 9 ~ 11%, at 150 DEG C of temperature, tensile strength is 180 ~ 200MPa, yield strength is 120 ~ 140MPa, and elongation is 15 ~ 19%, and its performance index are obviously better than commercial AZ91 and AM60 alloy.

The magnesium alloy using the inventive method to manufacture, has higher room temperature obdurability and resistance to elevated temperatures, and is easy to casting forming.Concrete feature is as follows:

(1) obdurability of magnesium alloy is usually improved by adding appropriate Ca, Sn unit in alloy.Ca element has fire retardation, can crystal grain thinning, and forms high-melting-point Al ₂ca strengthening phase is to put forward heavy alloyed thermotolerance.Add Sn element can improve the mobility of magnesium alloy, reduce the hot tearing susceptibility of magnesium alloy, the particulate state Mg that Sn and Mg can be formed ₂sn strengthening phase, contributes to carrying heavy alloyed obdurability; In addition, because Sn element is the element typically in magnesium alloy with precipitation strength effect, alloy of the present invention can also improve the comprehensive mechanical property of alloy further by thermal treatment.

(2) cost of metal Ca and Sn is lower than rare earth metal, is more suitable for industrial production.

(3) in alloy, the object of metallic aluminium is added: one is form Al in order to make up owing to adding Ca ₂ca and the Al element that consumes, two is that the Al content increased in alloy can put forward heavy alloyed mobility, is beneficial to casting forming.

(4) the industrial AM60 wide material sources of mother alloy, melting technology is ripe, and highly versatile, is easy to realize suitability for industrialized production.

embodiment:

Below in conjunction with specific embodiment, the present invention is described further, but protection scope of the present invention is not by the restriction of embodiment.

The present invention relates to a kind of high-toughness heat-resistant diecast magnesium alloy, with industrial magnesium alloy AM60 ingot casting for mother alloy, add Ca, Sn and Al to make, it is characterized in that: the chemical constitution of this alloy is by mass percentage: 6.5 ~ 8.0%Al, 0.95 ~ 1.1%Ca, 0.45 ~ 0.8%Sn, 0.2 ~ 0.4%Mn, Zn≤0.02%, impurity element S i≤0.03%, other impurity (Fe+Ni+Cu)≤0.01%, surplus is Mg.

A preparation method for high-toughness heat-resistant diecast magnesium alloy described above, step is as follows: select industrial magnesium alloy AM60 ingot casting to be mother alloy, master alloy ingot is preheated to 200 ~ 250 DEG C, and is having SF ₆and N ₂the melt in furnace of mixture gas shield; after mother alloy all melts; temperature is risen to 700 DEG C, by pure Al, directly add in melt after pure Ca and pure Sn preheating; through being uniformly mixed; continue to be warming up to 710 ~ 720 DEG C, leave standstill 20 ~ 30 minutes, be then cooled to 690 ~ 700 DEG C; take surface scum off, carry out die casting.

embodiment 1

Select industrial magnesium alloy AM60 to be mother alloy, alloy is preheated to 200 DEG C, and at SF ₆and N ₂mixed gas protected under melt, temperature is risen to 700 DEG C, directly adds after pure Al, pure Ca and pure Sn preheating in melt; through being uniformly mixed, continuing to be warming up to 710 DEG C, leaving standstill 30 minutes; then be cooled to 700 DEG C, take surface scum off, carry out die casting.

The composition (mass percent) as shown in the table of the foundry goods obtained:

Ca	Sn	Al	Mn	Zn	Si	Fe+Ni+Cu	Mg
								0.95	0.65	6.52	0.32	0.014	0.026	0.009	Surplus

Room temperature tensile intensity is 260.8MPa, and yield strength is 170.3MPa, and elongation is that at 10.5%, 150 DEG C of temperature, tensile strength is 180.5MPa, and yield strength is 121.3MPa, and elongation is 17.8%.

embodiment 2

Select industrial magnesium alloy AM60 to be mother alloy, alloy is preheated to 220 DEG C, and at SF ₆and N ₂mixed gas protected under melt, temperature is risen to 700 DEG C, directly adds after pure Al, pure Ca and pure Sn preheating in melt; through being uniformly mixed, continuing to be warming up to 720 DEG C, leaving standstill 30 minutes; then be cooled to 690 DEG C, take surface scum off, carry out die casting.

Obtain the composition following (mass percent) of foundry goods:

Ca	Sn	Al	Mn	Zn	Si	Fe+Ni+Cu	Mg
								0.95	0.73	7.15	0.36	0.018	0.023	0.008	Surplus

Room temperature tensile intensity is 270.3MPa, and yield strength is 179.6MPa, and elongation is that at 10.1%, 150 DEG C of temperature, tensile strength is 192.7MPa, and yield strength is 130.6MPa, and elongation is 16.7%.

embodiment 3

Select industrial magnesium alloy AM60 to be mother alloy, alloy is preheated to 250 DEG C, and at SF ₆and N ₂mixed gas protected under melt, temperature is risen to 700 DEG C, directly adds after pure Al, pure Ca and pure Sn preheating in melt; through being uniformly mixed, continuing to be warming up to 720 DEG C, leaving standstill 20 minutes; then be cooled to 700 DEG C, take surface scum off, carry out die casting.

Obtain the composition following (mass percent) of foundry goods:

Ca	Sn	Al	Mn	Zn	Si	Fe+Ni+Cu	Mg
								1.06	0.45	8.0	0.20	0.015	0.03	0.009	Surplus

Room temperature tensile intensity is 279.7MPa, and yield strength is 184.8MPa, and elongation is that at 9.3%, 150 DEG C of temperature, tensile strength is 199.8MPa, and yield strength is 139.7MPa, and elongation is 15.2%.

embodiment 4

Select industrial magnesium alloy AM60 to be mother alloy, alloy is preheated to 230 DEG C, and at SF ₆and N ₂mixed gas protected under melt, temperature is risen to 700 DEG C, directly adds after pure Al, pure Ca and pure Sn preheating in melt; through being uniformly mixed, continuing to be warming up to 715 DEG C, leaving standstill 20 minutes; then be cooled to 695 DEG C, take surface scum off, carry out die casting.

Ca	Sn	Al	Mn	Zn	Si	Fe+Ni+Cu	Mg
								1.10	0.56	7.89	0.25	0.020	0.019	0.010	Surplus

Room temperature tensile intensity is 267.8MPa, and yield strength is 178.3MPa, and elongation is that at 10.9%, 150 DEG C of temperature, tensile strength is 188.5MPa, and yield strength is 125.8MPa, and elongation is 19.0%.

embodiment 5

Select industrial magnesium alloy AM60 to be mother alloy, alloy is preheated to 250 DEG C, and at SF ₆and N ₂mixed gas protected under melt, temperature is risen to 700 DEG C, directly adds after pure Al, pure Ca and pure Sn preheating in melt; through being uniformly mixed, continuing to be warming up to 710 DEG C, leaving standstill 25 minutes; then be cooled to 700 DEG C, take surface scum off, carry out die casting.

Ca	Sn	Al	Mn	Zn	Si	Fe+Ni+Cu	Mg
								0.97	0.80	6.50	0.40	0.016	0.020	0.007	Surplus

Room temperature tensile intensity is 276.8MPa, and yield strength is 173.4MPa, and elongation is that at 9.9%, 150 DEG C of temperature, tensile strength is 186.5MPa, and yield strength is 135.8MPa, and elongation is 16.3%.

Conclusion:

In order to improve the problem that obdurability is lower and thermotolerance is poor of existing commercial diecast magnesium alloy, the present invention by adding metal Ca, Sn and Al in AM60 alloy, prepare have high tough and high heat resistance can diecast magnesium alloy.This alloy has the advantage of cost is low, melt treatment is simple, die cast is functional, higher obdurability and thermotolerance, is easy to promote the use of, is particularly suitable for mass-producing commercial production, has market potential.The room temperature of this alloy and mechanical behavior under high temperature index are all higher than commercial AZ91 and AM60 alloy.

Claims

1. a high-toughness heat-resistant diecast magnesium alloy, it is characterized in that: with industrial magnesium alloy AM60 ingot casting for mother alloy, add Ca, Sn and Al to make, it is characterized in that: the chemical constitution of this alloy is by mass percentage: 6.5 ~ 8.0%Al, 0.95 ~ 1.1%Ca, 0.45 ~ 0.8%Sn, 0.2 ~ 0.4%Mn, Zn≤0.02%, impurity element S i≤0.03%, other impurity (Fe+Ni+Cu)≤0.01%, surplus is Mg.

2. a preparation method for high-toughness heat-resistant diecast magnesium alloy as claimed in claim 1, is characterized in that: the method step is as follows: select industrial magnesium alloy AM60 ingot casting to be mother alloy, master alloy ingot is preheated to 200 ~ 250 DEG C, and is having SF ₆and N ₂the melt in furnace of mixture gas shield; after mother alloy all melts; temperature is risen to 700 DEG C, by pure Al, directly add in melt after pure Ca and pure Sn preheating; through being uniformly mixed; continue to be warming up to 710 ~ 720 DEG C, leave standstill 20 ~ 30 minutes, be then cooled to 690 ~ 700 DEG C; take surface scum off, carry out die casting.

3. the preparation method of high-toughness heat-resistant diecast magnesium alloy according to claim 2, it is characterized in that: this Alloy At Room Temperature tensile strength is 260 ~ 280MPa, yield strength is 170 ~ 185MPa, elongation is 9 ~ 11%, at 150 DEG C of temperature, tensile strength is 180 ~ 200MPa, yield strength is 120 ~ 140MPa, and elongation is 15 ~ 19%.