CN103484722B

CN103484722B - Pressure casting and heat treatment process of zinc alloy

Info

Publication number: CN103484722B
Application number: CN201310462082.7A
Authority: CN
Inventors: 季吉清
Original assignee: SUZHOU LIDA CASTING CO Ltd
Current assignee: SUZHOU LIDA CASTING CO Ltd
Priority date: 2013-09-30
Filing date: 2013-09-30
Publication date: 2015-04-22
Anticipated expiration: 2033-09-30
Also published as: CN103484722A

Abstract

The invention provides a novel zinc alloy for a bearing and a corresponding pressure casting and heat treatment process. The pressure casting and heat treatment process comprises the steps of raw material preparation, melting, and pressure casting and heat treatment and the like. The zinc alloy is excellent in mechanical performance, especially the strength and the hardness suitable for a heavy-load and high-temperature environment. The pressure casting and heat treatment process of the zinc alloy specifically comprises the following steps: preparing raw materials through a proper amount of simple alloy elements; obtaining a casting through a proper melting process and subsequent pressure casting; and subjecting the casting to heat treatment and obtaining the zinc alloy, wherein the elements, the melting process, the pressure casting process parameters and the heat treatment process parameters of the alloy are all optimized to obtain a product with excellent performance.

Description

A kind of die casting of zinc alloy and thermal treatment process

Technical field

The present invention relates to the technical field that zinc and alloy thereof are applied in mechanical industry, a kind of novel zinc alloy being applied to the wearing pieces such as bearing is particularly provided, and corresponding die casting and thermal treatment process.

Background technology

In machinery industry field, antifriction metal mainly uses traditional copper base alloy and Babbitt metal foundry goods, but the raw material of these two kinds of alloys and manufacturing cost are all very high, especially along with the develop rapidly of the industrial circles such as telecommunications, demand for copper grows with each passing day, in addition copper belongs to the scarce resource of China, causes annual China to need a large amount of from external import copper, further have compressed the space that copper base alloy uses as bearing base part starting material.

Use to substitute traditional copper base alloy, the foundry goods of current zinc base alloy as wear resistant friction reducing material by a large amount of manufacture for the bearing such as bearing shell, axle sleeve type component.Although zinc base alloy has the excellent mechanical property such as intensity, plasticity and toughness equally, and outstanding wear resistant friction reducing performance, but its primary alloy constituent proportion differs greatly, have that alloy graining temperature range is wide, the defect such as loosening easily appears in castingprocesses, segregation, had a strong impact on zinc base alloy because of application, and its use temperature is also lower, a large amount of heat releases usually produced due to frictional wear under fully loaded transportation condition make component temperature overheating and are difficult to use.

Therefore, obtain one and there is excellent castability, the novel zinc base alloy used under higher temperature conditions can be met simultaneously there is important Research Significance and application prospect widely.

Summary of the invention

Namely object of the present invention is to provide a kind of formula of new zinc alloy and corresponding die casting and thermal treatment process.

Zinc alloy in the present invention has following chemical constitution: with weight (wt.%), Al 17-20, Cu2.5-4.5, Mg 0.05-0.1, Si 1.5-3, Sb 0.02-0.05, Sc 0.05-0.1, surplus is Zn and inevitable impurity.

Concrete, die casting and the thermal treatment process of the zinc alloy in the present invention comprise the following steps:

1) prepare burden: with weight (wt.%), Al 17-20, Cu 2.5-4.5, Mg 0.05-0.1, Si 1.5-3, Sb 0.02-0.05, Sc 0.05-0.1, surplus is that Zn and inevitable impurity prepare raw material; Wherein above-mentioned alloying constituent come from purity be 99.99% pure zinc, the aluminum silicon alloy of weight ratio 1:1, the zinc antimony alloy of weight ratio 1:1, the aluminum scandium alloy of weight ratio 1:1, electrolytic copper, pure magnesium and commercial-purity aluminium.

2) melting: first pure zinc is placed in smelting furnace and is heated to 450-470 DEG C of maintenance 5-10min, temperature is risen to 820-850 DEG C subsequently and add commercial-purity aluminium, aluminum silicon alloy, aluminum scandium alloy and electrolytic copper Keep agitation are until aluminum silicon alloy and electrolytic copper all melt, be cooled to 680-700 DEG C afterwards and add zinc antimony alloy and Keep agitation until zinc antimony alloy all melts, be cooled to 620-650 DEG C subsequently and pure magnesium be pressed into bottom melt and maintain at least 5min, stir melt afterwards and be again warming up to 720-750 DEG C and add refining agent simultaneously and carry out refining, after leaving standstill 10-15min, melting is completed after inspection bath composition is qualified.

3) die casting: after melt qualified for composition is cooled to 550-580 DEG C, die casting is preheated in the mold cavity of 180-200 DEG C to passing through, the melt flow of wherein filling when type starts is 0.5-0.8m/s, casting pressure is 60-70MPa, fill type rate more than 50% after, the flow velocity improving melt is 90-100MPa to 3-3.5m/s, casting pressure, terminates until fill type die casting.

4) thermal treatment: by die casting foundry goods under 380-400 DEG C of condition after homogenizing 20-24h after shrend to room temperature, then be warming up to the ageing treatment that 120-150 DEG C is carried out 5-10h.

Preferred further, described be die cast as melt qualified for composition is cooled to 560 DEG C after die casting to through being preheated in the mold cavity of 180 DEG C, the melt flow of wherein filling when type starts is 0.6m/s, casting pressure is 65MPa, fill type rate more than 50% after, the flow velocity improving melt is 95MPa to 3.3m/s, casting pressure, terminates until fill type die casting.

Further preferred, described thermal treatment is by die casting foundry goods under 390 DEG C of conditions after homogenizing 22h after shrend to room temperature, then is warming up to the ageing treatment that 130 DEG C are carried out 8h.

The invention has the advantages that: (1) reasonable design composition of bearing zinc alloy, obtains the zinc alloy with excellent die casting and aging performance; (2) take suitable raw material and melting technology, ensure that the performance of alloy; (3) have selected best die-casting technological parameter to obtain the aluminium alloy of excellent performance; (4) have employed the most effective thermal treatment process and parameter, improve the performance of aluminium alloy to greatest extent; (5) zinc alloy not only has excellent ambient temperature mechanical properties, even if still can meet service requirements under the condition more than 150 DEG C.

Embodiment

Embodiment 1-4, and comparative example 1-9:

1) prepare burden: prepare burden by the alloy proportion given by table 1, wherein alloying constituent comes from pure zinc, the aluminum silicon alloy of weight ratio 1:1, the zinc antimony alloy of weight ratio 1:1, the raw material such as aluminum scandium alloy, electrolytic copper, pure magnesium, commercial-purity aluminium of weight ratio 1:1 that purity is 99.99%.

2) melting: first pure zinc is placed in smelting furnace and is heated to 460 DEG C of maintenance 10min, temperature is risen to 830 DEG C subsequently and add commercial-purity aluminium, aluminum silicon alloy, aluminum scandium alloy and electrolytic copper Keep agitation are until aluminum silicon alloy and electrolytic copper all melt, be cooled to 690 DEG C afterwards and add zinc antimony alloy and Keep agitation until zinc antimony alloy all melts, be cooled to 640 DEG C subsequently and pure magnesium be pressed into bottom melt and maintain at least 5min, stir melt afterwards and be again warming up to 740 DEG C and add refining agent simultaneously and carry out refining, after leaving standstill 15min, melting is completed after inspection bath composition is qualified.

3) die casting: after melt qualified for composition is cooled to 560 DEG C, die casting is preheated in the mold cavity of 180 DEG C to passing through, the melt flow of wherein filling when type starts is 0.6m/s, casting pressure is 65MPa, fill type rate more than 50% after, the flow velocity improving melt is 95MPa to 3.3m/s, casting pressure, terminates until fill type die casting.

4) thermal treatment: by die casting foundry goods under 390 DEG C of conditions after homogenizing 22h after shrend to room temperature, then be warming up to the ageing treatment that 130 DEG C are carried out 8h.

Table 1

As shown in Table 1, aluminium content has important impact for the intensity of alloy system and hardness, if aluminium content is too low, the room temperature strength of alloy system can be caused all can not to meet the requirement of use, but the interpolation of aluminium content can not be excessive, otherwise not only can not continue to put forward heavy alloyed mechanical property, the usefulness of other alloying elements to be affected for the destruction of alloy system whole machine balancing due to aluminium on the contrary, cause the obvious deficiency of hot strength.

Copper is the main alloy element of aluminium-zinc alloy, it has important effect improving the wear resistance under alloy strength and high-load condition, in order to play above-mentioned effect, the addition of copper at least should more than 2.5, but the excessive interpolation of copper can form a large amount of intermetallic compounds and cause the catalysis of alloy system, reduce obdurability on the contrary, therefore the addition of copper is no more than 4.5.

The interpolation of magnesium mainly can prevent the generation of the intergranular corrosion of zinc base alloy, certain inhibition can be played for growing up of crystal grain simultaneously, thus improve intensity to a certain extent, in order to play above-mentioned effect, the content of magnesium should more than 0.05, if but the content of magnesium has exceeded 0.1, then can form excessive unnecessary intermetallic compound brittlement phase with silicon, hinder the effect of the alloying element such as antimony, scandium simultaneously.

Silicon is the main effect playing antifriction antiwear in alloy system, in order to ensure silicon be uniformly distributed play its effectiveness, should ensure that the content of silicon is more than 1.5, but the content of silicon can not be too high, otherwise easily separate out at crystal boundary, and form intermetallic compound brittlement phase, thus the mechanical property of severe exacerbation alloy.

Antimony and scandium have mainly played stable alloy system tissue, avoid the deterioration of the zinc alloy system mechanical property caused due to thermal treatment, timeliness and heavy duty, applied at elevated temperature environment, scandium also serves the effect of grain refining to a certain extent simultaneously, can find out that the two is worked in coordination with and can play maximum stabilization, but the content of the two is unsuitable too high, otherwise can destroy the mechanical property of alloy.

Significantly, the alloy system in the application, the unforeseeable mechanical property obtaining excellence, particularly can still keep enough physical strengths and hardness under heavy duty, applied at elevated temperature environment.

Embodiment 5-7, and comparative example 10-17, the chemical composition of alloy is identical with embodiment 2, the optimization selection of the processing parameter in paper examines press casting procedure, parameter choose and results of property see table 2.

Although adopt low speed, at a high speed two kinds of different melt flow to be techniques well known in the art to control the defects such as pore in press casting procedure, as shown in Table 2, melt flow and casting pressure how is selected still to have a great impact:

For melt flow and the casting pressure of the low-speed stage of zinc alloy of the present invention, melt flow should be controlled between 0.5-0.8m/s, too low melt flow can cause melt cooling too fast and affect the die casting performance of melt, thus the final mechanical property worsening alloy, and be also unfavorable for the raising of production efficiency.Too high melt flow then can cause the appearance of turbulent flow and easily be involved in gas and oxide inclusion, can cause the rapid solidification of local melt simultaneously and produce the defects such as pore.The increase of casting pressure obviously can improve the mechanical property of material, this mainly has benefited from the raising of alloy compactness that pressure increase produces and the minimizing of defect, in order to ensure this effect, for zinc alloy system of the present invention, casting pressure at least should be 60MPa, but excessive casting pressure can't obtain more performance to take on a new look, and can cause the loss that equipment, mould etc. are too fast on the contrary, therefore the upper limit of casting pressure is set as 70MPa.

For melt flow and the casting pressure of high speed stage, should control melt flow between 3-3.5m/s, casting pressure is between 90-100MPa, and it, for press casting procedure and the impact of alloy mechanical property and the similar of low-speed stage, repeats no more.

Significantly, the alloy system in the application, has the die-casting technological parameter being most suitable for it, against the decline that all may cause alloy property in the most optimized parameter.

Table 2

Embodiment 8-9, and comparative example 18-21, the chemical composition of alloy is identical with embodiment 2, the paper examines optimization selection of heat treatment process parameter, parameter choose and results of property see table 3.

Table 3

As shown in Table 3, the temperature of homogenizing can not be too low, and need time enough, otherwise will be difficult to play eliminate stress, and improves the effect of mechanical property; Opposite thermal is too high, and tissue may be caused to change and have a strong impact on mechanical property.The temperature of timeliness also must be suitable, and too low aging temp and time can not play a role and obtain stable mechanical property, and too high aging temp then can have a strong impact on the intensity of alloy.

To sum up, the composition of the present invention's zinc base alloy system that has been first appropriate design, to ensure that zinc alloy has enough mechanical properties, particularly be applicable to the mechanical property under heavy duty, applied at elevated temperature environment, the processing parameter of simultaneously optimum option die casting and thermal treatment process step subsequently and parameter, thus obtain the alloy mechanical property of the best.

Claims

1. the die casting of zinc alloy and a thermal treatment process, its concrete steps are as follows:

1) prepare burden: with weight (wt.%), Al 17-20, Cu 2.5-4.5, Mg 0.05-0.1, Si 1.5-3, Sb 0.02-0.05, Sc 0.05-0.1, surplus is that Zn and inevitable impurity prepare raw material; Wherein above-mentioned alloying constituent come from purity be 99.99% pure zinc, the aluminum silicon alloy of weight ratio 1:1, the zinc antimony alloy of weight ratio 1:1, the aluminum scandium alloy of weight ratio 1:1, electrolytic copper, pure magnesium and commercial-purity aluminium;

2) melting: first pure zinc is placed in smelting furnace and is heated to 450-470 DEG C of maintenance 5-10min, temperature is risen to 820-850 DEG C subsequently and add commercial-purity aluminium, aluminum silicon alloy, aluminum scandium alloy and electrolytic copper Keep agitation are until aluminum silicon alloy and electrolytic copper all melt, be cooled to 680-700 DEG C afterwards and add zinc antimony alloy and Keep agitation until zinc antimony alloy all melts, be cooled to 620-650 DEG C subsequently and pure magnesium be pressed into bottom melt and maintain at least 5min, stir melt afterwards and be again warming up to 720-750 DEG C and add refining agent simultaneously and carry out refining, after leaving standstill 10-15min, melting is completed after inspection bath composition is qualified,

3) die casting: after melt qualified for composition is cooled to 550-580 DEG C, die casting is preheated in the mold cavity of 180-200 DEG C to passing through, the melt flow of wherein filling when type starts is 0.5-0.8m/s, casting pressure is 60-70MPa, fill type rate more than 50% after, the flow velocity improving melt is 90-100MPa to 3-3.5m/s, casting pressure, terminates until fill type die casting;

2. the die casting of zinc alloy according to claim 1 and thermal treatment process, it is characterized in that: after melt qualified for composition is cooled to 560 DEG C by described being die cast as, die casting is preheated in the mold cavity of 180 DEG C to passing through, the melt flow of wherein filling when type starts is 0.6m/s, casting pressure is 65MPa, fill type rate more than 50% after, the flow velocity improving melt is 95MPa to 3.3m/s, casting pressure, terminates until fill type die casting.

3. the die casting of zinc alloy according to claim 1 and thermal treatment process, is characterized in that: described thermal treatment for by die casting foundry goods under 390 DEG C of conditions after homogenizing 22h after shrend to room temperature, then be warming up to the ageing treatment that 130 DEG C are carried out 8h.