KR20160042056A - High strength aluminum alloy fin stock for heat exchanger - Google Patents

Abstract

The present invention provides an aluminum alloy fin stock alloy material for use in heat exchangers having higher strength and improved sag resistance. This aluminum alloy fin stock alloy material was made by direct cooling (DC) casting.

Description

HIGH STRENGTH ALUMINUM ALLOY FIN STOCK FOR HEAT EXCHANGER FOR HEAT EXCHANGER

Cross reference of related application

This application claims the benefit of U.S. Provisional Patent Application Serial No. 61 / 863,568, filed August 8, 2013, which is hereby incorporated by reference in its entirety.

The present invention relates to materials science, material chemistry, metallurgy, aluminum alloys, aluminum making and related fields. The present invention provides a new aluminum alloy for use in the manufacture of heat exchanger fins, which is again employed in a variety of heat exchanger devices, such as automotive radiators, condensers, evaporators and related devices.

There is a need for an aluminum alloy fin stock having high strength and improved sag resistance high strength for use in various heat exchanger applications, including automotive radiators. For high performance heat exchanger applications, aluminum alloy pins with strong pre-braze mechanical properties and good behavior during brazing, i.e. improved braze material deflection resistance and reduced pin wear, and good strength and conductivity properties after brazing, It is necessary to obtain stock.

The present invention provides an aluminum alloy fin stock alloy material for use in heat exchangers having higher strength and improved sag resistance. This aluminum alloy fin stock alloy material was made by direct cooling (DC) casting.

DC finstock materials have been developed that have a desirable braze transition (H14 temper) and post-braze mechanical properties, deflection resistance, corrosion resistance, and conductivity. Aluminum alloy finstock alloys exhibit larger grain and improved strength before brazing.

Aluminum alloy finstock alloys can be used in a variety of applications, for example in heat exchangers. This fin stock is particularly useful for high performance lightweight automotive heat exchangers and can be used for other brazing applications including but not limited to HVAC. In one embodiment, the aluminum alloy finstock alloy can be used in automotive heat exchangers, such as radiators, condensers, and evaporators. Other objects and advantages of the present invention will become apparent from the following detailed description of embodiments of the present invention.

The present invention provides an aluminum alloy fin stock alloy material for use in a heat exchanger, such as automotive heat exchangers, with higher strength, improved corrosion resistance, and improved sag resistance. This aluminum alloy fin stock alloy material was made by direct chill casting.

This DC pinstock material exhibits the mechanical properties, sag resistance, corrosion resistance and conductivity after the preferred braze (H14 temper) and braze. Aluminum alloy finstock alloys exhibit larger particles and improved strength before brazing.

Aluminum alloy finstock alloys can be used in a variety of applications, for example in heat exchangers. In one embodiment, the aluminum alloy finstock alloy can be used in automotive heat exchangers, such as radiators, condensers, and evaporators.

In one embodiment, the DC finstock material comprises about 0.8-1.4% Si, 0.4-0.8% Fe, 0.05-0.4% Cu, 1.2-1.7% Mn and 1.2-2.3% Zn, and the balance aluminum . All% values are weight (wt)%.

In another embodiment, the DC finstock material comprises about 0.9-1.3% Si, 0.45-0.75% Fe, 0.10-0.30% Cu, 1.3-1.7% Mn and 1.30-2.2% Zn, and the balance aluminum .

In yet another embodiment, the DC finstock material comprises about 0.9-1.2% Si, 0.50-0.75% Fe, 0.15-0.30% Cu, 1.4-1.6% Mn, and 1.4-2.1% Zn, Aluminum.

Alternatively, Cr and / or Zr or other particle size controlling elements may be present in the alloy composition in an amount of 0.2% or less, 0.15% or less, 0.1% or less, 0.05% or less, or 0.03% or less. All% values are weight (wt)%.

It should be understood that the alloy composition described herein may also include less than 0.05% of other minor elements referred to as unintended elements.

How to make ingots

The ingots described here are made by a direct cooling (DC) process commonly used throughout the aluminum sheet industry, where a large ingot of ~ 1.5 mx 0.6 mx 4 m has a shallow mold or metal And is then cast from a large holding furnace. The ingot to be solidified is continuously cooled by the impingement of the cooling water, and is withdrawn at a low speed from the base of the mold until the entire ingot or ingot is completed. Once cooled from the casting process, the rolling surfaces of the ingot are machined to remove surface segregation and unevenness. The machined ingot is preheated for hot rolling. The preheat temperature and duration are controlled to a low level so that the finished fin stock remains brazed and then retains large grain size and high strength. The ingot is hot rolled to form a coil and then cold rolled. The cold rolling process takes place in several steps and an interanneal of about 300-450 DEG C is applied to recrystallize the material before the final cold rolling step. Next, the material is cold rolled to obtain the desired final gauge and is cut into narrow strips suitable for the manufacture of radiators and other automotive heat exchangers. Preheating of the ingot prior to hot rolling is carried out such that the final metal temperature achieved is about 480 DEG C and is maintained here for an average of about 4 hours (typically at least about 2 hours and up to about 12 hours). Several ingots (about 8 to 30) are loaded into the furnace and preheated to rolling temperature by gas or electricity. The aluminum alloy is typically rolled in the range of about 450 캜 to about 560 캜. If the temperature is too cold, the roll load is too high, and if the temperature is too hot, the metal may be too dry and broken in the mill. In this case, the preheating temperature is lower than that of other aluminum products, and the holding time is relatively short, which limits the growth of the dispersion to reduce the particle size after the final brazing. In fact, hot mills are intended to roll many different ingots and alloys and can not always roll ingot at the soak time. In one embodiment, the minimum soak time is about 2 hours at about 480 [deg.] C. During manufacture, the applied intermediate annealing temperature was about 400 캜 for an average of about 3 hours followed by application of about 29%% cold working (CW) to the final gauge. The% CW is the degree of cold rolling applied so that the material is ultimately in the required strength range. This% cold working is defined as: (initial gauge - final gauge) * 100 / initial gauge. As the cold working increases, the H14 strength increases, but the particle size and sag resistance after the final braze decrease. 29% is relatively low for most aluminum rolling applications.

In one embodiment, the preheat practice at about 480 ° C for an average of 4 hours is employed at an intermediate annealing temperature of about 300-400 ° C and a% CW of about 25-35% to the final gauge.

The finished cold rolled coil is then cut into a number of narrow strips of the width required by the heat exchanger manufacturer for forming, assembling and brazing into a finished heat exchanger.

The following examples serve to further illustrate the present invention, but do not constitute any limitation of the invention at the same time. On the contrary, it is to be clearly understood that, after reading the description herein, it will be appreciated that various embodiments, modifications and equivalents of the invention may be suggested to those skilled in the art without departing from the spirit of the invention .

example

A DC case alloy composition was made. The composition range of this alloy was within the following specifications: 1.1 ± 0.1% Si, 0.6 ± 0.1% Fe, 0.2 ± 0.05% Cu, 1.4 ± 0.1% Mn and 1.50 ± 0.1% Zn, aluminum. The alloying material had a minimum ultimate tensile strength of ~ 130 MPa. The alloy material has an average conductivity after brazing of ~ 43 IACS (ie, pure copper is 100% conductive) and an open circuit potential corrosion value of -741 mV (for a standard calomel electrode (SCE)) I have. The alloying material produced exhibited deflection values between 28 millimeters when the final gauge was 49 micrometers to 43 millimeters when the final gauge was 83 micrometers, which was within the specifications required for this gauge. This value was measured after application of a simulated brazing cycle in which the sample was heated to a temperature of 605 占 폚 to simulate the temperature time profile of the commercial brazing process and cooled to room temperature for a period of about 20 minutes. The alloy material produced varied in gauge between 49 and 83 micrometers.

All patents, patent applications, publications, and abstracts mentioned above are hereby incorporated by reference in their entirety. Various embodiments of the invention have been described in order to fulfill the various objects of the invention. It should be appreciated that this embodiment is a simple description of the principles of the invention. Many modifications and variations of this invention will be readily apparent to those skilled in the art without departing from the scope and spirit of the invention as defined in the following claims.

Claims (16)

In the aluminum alloy, about 0.8-1.4 wt% Si, 0.4-0.8 wt% Fe, 0.05-0.4 wt% Cu, 1.2-1.7 wt% Mn, and 1.20-2.3 wt% Zn, and the balance aluminum ≪ / RTI > The method of claim 1, further comprising the steps of: providing about 0.9-1.3 wt% Si, 0.45-0.75 wt% Fe, 0.10-0.3 wt% Cu, 1.3-1.7 wt% Mn, and 1.30-2.2 wt% Zn, ≪ / RTI > The method of claim 1, further comprising: adding about 0.9-1.2 wt% Si, 0.5-0.75 wt% Fe, 0.15-0.3 wt% Cu, 1.4-1.6 wt% Mn and 1.4-2.1 wt% Zn, ≪ / RTI > 4. The aluminum alloy according to any one of claims 1 to 3, further comprising one or both of Cr and / or Zr of 0.2% by weight or less. 6. An aluminum alloy according to any one of claims 1 to 4,
Casting the aluminum alloy directly into an ingot;
Preheating the ingot at 450 to 560 DEG C for 2 to 16 hours;
Hot rolling the preheated ingot;
Cold-rolling the ingot;
Inter-annealing at a temperature of 300-450 占 폚; And
After the intermediate annealing, a step of performing a final cold rolling step achieving 25-35%% cold working (% CW)
≪ / RTI > aluminum alloy pin stock material. 6. The aluminum alloy fin stock material of claim 5, wherein the ingot is preheated at 480 DEG C for 2-12 hours. The aluminum alloy pin stock material as claimed in claim 5 or 6, wherein the intermediate annealing temperature is 300-400 캜. The aluminum alloy pin stock material as claimed in any one of claims 5 to 7, having a minimum ultimate tensile strength of ~ 130 MPa, measured after brazing. The aluminum alloy fin stock material according to any one of claims 5 to 7, having an erosion potential of -700 mV or less, measured after brazing. A heat exchanger comprising the aluminum alloy according to any one of claims 1 to 4 or the aluminum alloy fin stock material according to any one of claims 5 to 9. 11. The heat exchanger of claim 10, wherein the heat exchanger is an automotive heat exchanger. 11. The heat exchanger of claim 10, wherein the heat exchanger is a radiator, a condenser, or an evaporator. Use of the aluminum alloy according to any one of claims 1 to 4 or the aluminum alloy fin stock material according to any one of claims 5 to 9 for producing a heat exchanger pin. A method for manufacturing an aluminum alloy pin stock material,
Casting the aluminum alloy according to any one of claims 1 to 4 directly into an ingot;
Preheating the ingot at 450 to 560 DEG C for 2 to 16 hours;
Hot rolling the preheated ingot;
Cold-rolling the ingot;
Inter-annealing at a temperature of 300-450 占 폚; And
After the intermediate annealing, a step of performing a final cold rolling step achieving 25-35%% cold working (% CW)
≪ / RTI > 15. The method according to claim 14, wherein the ingot is preheated at 480 DEG C for 2-12 hours. The method according to claim 14 or 15, wherein the intermediate annealing temperature is 300-400 ° C.