阅读说明：本技术 一种降低热裂敏感倾向性的Al-4Cu(TiZr)合金及工艺 (Al-4Cu (TiZr) alloy capable of reducing hot cracking sensitivity tendency and process ) 是由 王志 王峰 周乐 毛萍莉 刘诗萌 魏子淇 刘正 于 2021-07-09 设计创作，主要内容包括：一种降低热裂敏感倾向性的Al-4Cu(TiZr)合金及工艺,Al-4Cu(TiZr)合金的原料包括：工业纯Al、Al-30wt.％Cu中间合金和晶粒细化剂Al-0.3Ti-0.6Zr；该材料各元素质量百分比含量为：Cu：3.5-4.5wt.％、Ti0.1-0.4wt.％、Zr0.3-0.6wt.％,杂质总量小于等于0.40wt.％和余量为Al。工艺为：先将纯Al预热20-30min,180-200℃温度；熔化纯Al；将预热后的Al-30wt.％Cu中间合金和晶粒细化剂Al-0.3Ti-0.6Zr直接加入纯Al熔体中,搅拌混合均匀后,熔体温度继续升高到790-800℃,保温1-1.5小时；再降低到720-740℃,静置20-30分钟,扒去表面浮渣后浇铸到预热温度为200-250℃的热裂测试模具中30-60分钟,待铸件完全凝固后取出样品观察合金的热裂敏感倾向性。(An Al-4Cu (TiZr) alloy for reducing the susceptibility to heat cracking and a process thereof, wherein the Al-4Cu (TiZr) alloy comprises the following raw materials: commercially pure Al, Al-30 wt.% Cu master alloy and grain refiner Al-0.3Ti-0.6 Zr; the material comprises the following elements in percentage by mass: cu: 3.5-4.5 wt.%, Ti0.1-0.4 wt.%, Zr0.3-0.6 wt.%, total impurities less than or equal to 0.40 wt.%, and the balance Al. The process comprises the following steps: firstly, preheating pure Al for 20-30min at the temperature of 180-; melting pure Al; directly adding preheated Al-30 wt.% Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr into a pure Al melt, stirring and mixing uniformly, continuously increasing the temperature of the melt to 790 ℃ and 800 ℃, and preserving heat for 1-1.5 hours; and then reducing the temperature to 720-740 ℃, standing for 20-30 minutes, removing surface scum, casting into a thermal cracking test mould with the preheating temperature of 200-250 ℃ for 30-60 minutes, and taking out a sample after the casting is completely solidified to observe the thermal cracking sensitivity tendency of the alloy.)

1. An Al-4Cu (TiZr) alloy having a reduced tendency to heat cracking, characterized by: the Al-4Cu (TiZr) alloy comprises the following raw materials in percentage by mass: commercially pure Al, Al-30 wt.% Cu master alloy and grain refiner Al-0.3Ti-0.6 Zr; the material comprises the following elements in percentage by mass: cu3.5-4.5 wt.%, Ti0.1-0.4 wt.%, Zr0.3-0.6 wt.%, total impurities less than or equal to 0.40 wt.%, and the balance Al.

2. A process of making an Al-4cu (tizr) alloy according to claim 1 having reduced susceptibility to hot cracking, wherein: preparing raw materials and proportions as described in claim 1;

preheating and melting: preheating industrial pure Al to reduce the moisture on the surface of the industrial pure Al; melting industrial pure Al in a well-type electric furnace by using an alumina crucible;

mixing: after the industrial pure Al as the master alloy is completely melted, directly adding preheated Al-30 wt.% Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr into the industrial pure Al melt, mechanically stirring and uniformly mixing, continuously increasing the temperature of the melt to 790-800 ℃, and preserving the heat for 1-1.5 hours at the temperature;

casting: and after heat preservation, reducing the temperature to 720-740 ℃, standing for 20-30 minutes, removing surface scum, casting into a preheated thermal cracking test mould, and taking out a sample after the casting is completely solidified to observe the thermal cracking sensitivity tendency of the alloy.

3. The process of reducing the propensity for hot cracking of an Al-4cu (tizr) alloy according to claim 2, wherein: in the preheating and melting process, the preheating temperature of the industrial pure Al is 180-200 ℃, and the preheating time is 20-30 min.

4. The process of reducing the propensity for hot cracking of an Al-4cu (tizr) alloy according to claim 2, wherein: during the mixing process, Al-30 wt.% Cu master alloy and grain refiner;

before Al-0.3Ti-0.6Zr is added into the industrial pure Al master alloy melt, Al-30 wt.% of Cu master alloy and grain refiner Al-0.3Ti-0.6Zr are preheated for 20-30min at 20-50 ℃ higher than the preheating temperature of the industrial pure Al, and then are added into the industrial pure Al melt.

5. The process of reducing the propensity for hot cracking of an Al-4cu (tizr) alloy according to claim 2, wherein: the stirring speed of the mechanical stirring is 100-120rpm, and the stirring time is 5-10 minutes.

6. The process of reducing the propensity for hot cracking of an Al-4cu (tizr) alloy according to claim 2, wherein: the preheating temperature of the thermal cracking test mould is 200-250 ℃, and the preheating time is 30-60 minutes.

Technical Field

The invention belongs to the field of material performance optimization, and relates to an Al-4Cu (TiZr) alloy for reducing the hot cracking sensitivity tendency and a performance optimization process.

Background

The Al-Cu casting alloy is a heat-treatable casting alloy which is the earliest to be applied, has the greatest characteristic of high heat resistance and is the alloy with the highest heat resistance in all casting aluminum alloys. The high temperature strength thereof is improved as the copper content is increased. However, the copper content increases, the alloy density increases, the brittleness increases, the welding performance decreases, and the corrosion resistance decreases. When the Cu element content in the Al-Cu alloy is 4-6 wt.%, the heat treatment strengthening effect of the Al-Cu alloy is best; the alloy has high heat treatment effect and heat stability, and is suitable for casting high temperature castings. However, this alloy has a large tendency to linear shrinkage and heat cracking, and is poor in casting performance, and is liable to cause heat cracking and casting defects.

Disclosure of Invention

Object of the Invention

The invention aims to solve the problems of high heat cracking tendency and casting defect generation of the existing Al-4Cu alloy, and provides an optimization process for reducing the heat cracking sensitivity tendency of Al-4Cu (TiZr), namely, an alloy with a grain refiner Al-0.3Ti-0.6Zr added in the Al-4Cu alloy, so that the heat cracking sensitivity tendency of the Al-4Cu (TiZr) alloy is reduced or no heat cracking is generated, and the needs of the industrial field are met.

Technical scheme

An Al-4Cu (TiZr) alloy having a reduced propensity for hot cracking, said Al-4Cu (TiZr) alloy comprising as raw materials: commercially pure Al, Al-30 wt.% Cu master alloy and grain refiner Al-0.3Ti-0.6 Zr; the material comprises the following elements in percentage by mass: cu: 3.5-4.5 wt.%, Ti0.1-0.4 wt.%, Zr0.3-0.6 wt.%, total impurities less than or equal to 0.40 wt.%, and the balance Al.

The process for reducing the hot cracking susceptibility of the Al-4Cu (TiZr) alloy comprises the following steps:

preheating and melting: preheating industrial pure Al for 20-30min at the temperature of 180-; melting industrial pure Al in a well-type electric furnace by using an alumina crucible;

mixing: after the industrial pure Al as the master alloy is completely melted, preheating Al-30 wt.% of Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr for 20-30min at 20-50 ℃ higher than the preheating temperature of the industrial pure Al, directly adding the preheated Al-30 wt.% of Cu intermediate alloy and the grain refiner Al-0.3Ti-0.6Zr into the industrial pure Al melt, mechanically stirring for 5-10min at a stirring speed of 100-120rpm, uniformly mixing, continuously increasing the melt temperature to 790-800 ℃, and preserving the heat at the temperature for 1-1.5 h;

casting: and after heat preservation, reducing the temperature to 720-740 ℃, standing for 20-30 minutes, removing surface scum, casting into a thermal cracking test mould with the preheating temperature of 200-250 ℃ for 30-60 minutes, and taking out a sample after the casting is completely solidified to observe the thermal cracking sensitivity tendency of the alloy.

The advantages and effects are as follows:

the Al-4Cu (TiZr) alloy prepared by the component proportion and the preparation process has obviously reduced heat cracking sensitivity, the melt is kept at the temperature of 790 ℃ and 800 ℃ for 1 to 1.5 hours, all solid phase grains and atom groups in the alloy liquid are dissolved and completely disappear, the tissue inheritance of the original alloy is damaged, and the metamorphic effect can be achieved without adding alloy elements, thereby reducing the heat cracking sensitivity tendency of the alloy.

Drawings

FIG. 1 is a thermal cracking curve of an Al-4Cu (TiZr) alloy according to example 1 of the present invention;

FIG. 2 is a thermal cracking curve of an Al-4Cu (TiZr) alloy according to example 2 of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

an Al-4Cu (TiZr) alloy having a reduced propensity for hot cracking, said Al-4Cu (TiZr) alloy comprising as raw materials: commercially pure Al, Al-30 wt.% Cu master alloy and grain refiner Al-0.3Ti-0.6 Zr; the material comprises the following elements in percentage by mass: cu: 3.5-4.5 wt.%, Ti0.1-0.4 wt.%, Zr0.3-0.6 wt.%, total impurities less than or equal to 0.40 wt.%, and the balance Al.

Example 1

Preheating industrial pure Al for 20min at the temperature of 180-200 ℃ to reduce the water on the surface of the industrial pure Al; the method comprises the steps of firstly melting industrial pure Al in a well-type electric furnace by adopting an alumina crucible, preheating Al-30 wt.% of Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr for 20-30min at 20-50 ℃ higher than the preheating temperature of the pure Al after the mother alloy is completely melted, directly adding the preheated intermediate alloy and the grain refiner Al-0.3Ti-0.6Zr into a melt, mechanically stirring at the stirring speed of 120rpm for 5-10min to mix uniformly, standing for 20-30min after the temperature of the melt is raised to 740 ℃, removing surface scum, casting into a thermal cracking test mold with the preheating time of 60min and the preheating temperature of 250 ℃, taking out a sample after a casting is completely solidified, and observing the thermal cracking sensitivity of the alloy. In the alloy, cu3.8 wt.%, ti0.2wt.%, zr0.5wt.%, total impurities 0.35 wt.%, and balance Al.

As the solidification process proceeds, the alloy is gradually cooled to generate a solidification contraction force, and the solidification contraction force is gradually increased with the solidification time. Once a crack has been initiated in the specimen, a relaxation of the contractile force occurs, which is manifested by a sudden drop in force or no further increase in force on the solidification contractile force curve (i.e. horizontal phase). FIG. 1 is a thermal cracking curve of an Al-4Cu (TiZr) alloy, and particularly, when the casting temperature is 740 ℃ and the mold temperature is 250 ℃, a section of a force reduction stage (marked by a vertical dotted line) is obviously arranged on a black solidification shrinkage force curve, so that the alloy generates obvious cracks, and a macroscopic picture of a sample example shows that the alloy generates large thermal cracks.

Example 2

Preheating industrial pure Al for 25min at 190 ℃ to reduce the moisture on the surface of the industrial pure Al; the method comprises the steps of firstly melting industrial pure Al in a well-type electric furnace by adopting an alumina crucible, preheating Al-30 wt.% of Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr for 25min at the temperature of 35 ℃ higher than the preheating temperature of the pure Al after the mother alloy is completely melted, directly adding the Al-30 wt.% of Cu intermediate alloy and the grain refiner Al-0.3Ti-0.6Zr into a melt, mechanically stirring at the stirring speed of 110rpm for 8min to mix uniformly, continuously raising the temperature of the melt to 800 ℃, preserving the temperature for 1 h at the temperature, then reducing the temperature to 740 ℃, standing for 25min, removing surface scum, casting into a thermal cracking test mould with the preheating time of 45min and the preheating temperature of 250 ℃, taking out a sample after a casting is completely solidified, and observing the thermal cracking sensitivity of the alloy. In the alloy, cu4.0 wt.%, ti0.3 wt.%, zr0.6 wt.%, total impurities 0.28 wt.%, and balance Al.

As can be seen from the analysis of the Al-4Cu (TiZr) alloy thermal cracking curve in FIG. 2, the Al-4Cu (TiZr) melt temperature was raised to 800 ℃ and after holding at this temperature for 1 hour, the melt temperature was lowered to 740 ℃ for casting, the mold temperature was 250 ℃, and there was no significant sudden drop or level of force on the black solidification shrinkage curve, indicating that the alloy did not crack significantly, and the observation of the macroscopic example photograph of the sample also indicates that there was no crack.

Example 3

Preheating industrial pure Al for 20min at 180 ℃ to reduce the moisture on the surface of the industrial pure Al; the method comprises the steps of firstly melting industrial pure Al in a well-type electric furnace by adopting an alumina crucible, preheating Al-30 wt.% of Cu intermediate alloy and grain refiner Al-0.3Ti-0.6Zr for 30min at 20 ℃ higher than the preheating temperature of the pure Al after the mother alloy is completely melted, directly adding the preheated intermediate alloy and the grain refiner Al-0.3Ti-0.6Zr into a melt, mechanically stirring at the stirring speed of 110rpm for 10min to mix uniformly, continuously raising the temperature of the melt to 795 ℃, preserving the heat at the temperature for 1.2 h, then reducing the temperature to 730 ℃, standing for 20min, removing surface scum, casting into a thermal cracking test mold with the preheating time of 30min and the preheating temperature of 230 ℃, taking out a sample after a casting is completely solidified, and observing the thermal cracking sensitivity tendency of the alloy. In the alloy, cu4.5wt.%, ti0.4wt.%, zr0.3wt.%, the total amount of impurities is 0.38 wt.%, and the balance is Al.

Example 4

Preheating industrial pure Al for 30min at 200 ℃ to reduce the moisture on the surface of the industrial pure Al; firstly melting industrial pure Al in a well-type electric furnace by adopting an alumina crucible, preheating Al-30 wt.% of Cu intermediate alloy and a grain refiner Al-0.3Ti-0.6Zr for 20min at 50 ℃ higher than the preheating temperature of the pure Al after the mother alloy is completely melted, directly adding the preheated intermediate alloy and the grain refiner Al-0.3Ti-0.6Zr into a melt, mechanically stirring at the stirring speed of 120rpm for 5min to mix uniformly, continuously raising the temperature of the melt to 800 ℃, preserving the heat at the temperature for 1.5 h, then reducing the temperature to 740 ℃, standing for 30min, removing surface scum, casting the melt into a thermal cracking test mould with the preheating time of 60min and the preheating temperature of 250 ℃, taking out a sample after a casting is completely solidified, and observing the thermal cracking sensitivity tendency of the alloy; in the alloy, cu4.3 wt.%, ti0.1 wt.%, zr0.4 wt.%, total impurities 0.28 wt.%, and the balance Al.

Experiments show that: under the test parameter conditions of the embodiment 3 and the embodiment 4, the black solidification shrinkage force curve does not have obvious sudden drop of force or is in a horizontal stage, which shows that the alloy does not generate obvious cracks, and the observation of the macro example picture of the sample also shows that the alloy does not generate cracks, so that the technical effect of the invention can be realized; example 2 is the best experimental data in the technical scheme of the invention, so the attached drawing of the specification gives the thermal cracking curve of the Al-4Cu (TiZr) alloy of example 2.