CN113198837B

CN113198837B - Preparation method of oil cooler chip material

Info

Publication number: CN113198837B
Application number: CN202110279105.5A
Authority: CN
Inventors: 刘二磊; 唐友增; 郭耿锋; 夏承东; 曹琦; 张斌; 周德敬
Original assignee: Yinbang Clad Material Co Ltd
Current assignee: Yinbang Clad Material Co Ltd
Priority date: 2021-03-16
Filing date: 2021-03-16
Publication date: 2023-05-12
Anticipated expiration: 2041-03-16
Also published as: CN113198837A

Abstract

The application discloses a preparation method of an oil cooler chip material. The preparation method of the oil cooler chip material comprises the following steps: preparing a core material, a first skin material and a second skin material; stacking the core material between the first skin material and the second skin material for compounding to obtain an aluminum alloy composite ingot; rolling the aluminum alloy composite ingot to obtain an O-state strip foil; determining the critical deformation of the O-state tape foil; pre-deforming the O-state belt foil by 0.5% -5% higher than the critical deformation; and carrying out low-temperature stress-relief annealing on the O-state strip foil subjected to the pre-deformation. The preparation method improves the preparation process, the prepared oil cooler chip material can be stably produced in mass, the corrosion after brazing can be effectively reduced, the corrosion resistance is higher, and the leakage risk of the oil cooler is reduced.

Description

Preparation method of oil cooler chip material

Technical Field

The application relates to the field of material preparation, in particular to a preparation method of an oil cooler chip material.

Background

In high performance, high power, intensified engines, oil coolers must be provided due to the high thermal loads. The oil cooler is arranged in the cooling water path, and the temperature of the lubricating oil is controlled by the temperature of the cooling water. When the temperature of the lubricating oil is high, the lubricating oil is cooled by cooling water. When the engine is started, heat is absorbed from the cooling water to quickly raise the temperature of the lubricating oil. The oil cooler is generally formed by brazing an aluminum alloy flange plate, a low chip, a top chip and fins.

Because the oil cooler has a complex structure, the inner cavity is provided with inner fins for welding, CAB brazing which needs to be coated with flux cannot be used, and VB brazing can only be used. VB brazing was a brazing technique developed by the GE company in the United states in 1968. VB breaks the oxide film on the aluminum surface by means of Mg evaporation in the brazing filler metal, and simultaneously, the workpiece is not oxidized any more by the degassing effect of Mg, so that the requirements on the post-welding yield strength and the tensile strength of the material are higher and higher in recent years, and 6-series aluminum alloy with timeliness gradually attracts attention in the industry.

The oil cooler is of a laminated structure, the core material is required to be stamped and deformed in the forming process, the raw material is required to have excellent extensibility before brazing, and the material is generally selected from an O state or an H22 state with relatively good extensibility.

In the prior art, the oil cooler adopts special structural design, one layer of oil is led in, one layer of water is led in, one layer of chip contacts lubricating oil, and one side contacts cooling water. Because the working environment is complex, the requirement on the post-welding corrosion resistance of chip raw materials is high. An important index affecting corrosion resistance is post-braze corrosion, which is serious and the corrosion resistance of the material must be poor.

One direction of the post-welding corrosion is controlled to be that the finished product is annealed to an H22 state, and the finished product obtains the maximum elongation and does not recrystallize, and the grain structure is still fibrous. The elongated fibrous tissue stretches the silicon diffusion channel and effectively prevents erosion. However, this method has a fatal disadvantage that the temperature requirement is very severe when part of the alloy is annealed to H22 state, the temperature is not easy to control in mass production, and the effect is not ideal in mass production stage.

Disclosure of Invention

The preparation method improves the preparation process, and the prepared oil cooler chip material can be stably produced in mass, can effectively reduce material corrosion, has higher corrosion resistance and reduces leakage risk.

According to an aspect of the present application, there is provided a method for preparing an oil cooler chip material, including:

preparing a core material, a first skin material and a second skin material;

stacking the core material between the first skin material and the second skin material for compounding to obtain an aluminum alloy composite ingot;

rolling the aluminum alloy composite ingot to obtain an O-state strip foil;

determining the critical deformation of the O-state tape foil;

pre-deforming the O-state belt foil by 0.5% -5% higher than the critical deformation;

and carrying out low-temperature stress-relief annealing on the O-state strip foil subjected to the pre-deformation.

According to some embodiments, the core material is 6 series and MOD aluminum alloy thereof, wherein the core material contains the following elements in weight ratio: less than or equal to 1wt% of Si, less than or equal to 0.6wt% of Fe, 0.2wt% to 0.7wt% of Cu, 0.1wt% to 1.5wt% of Mn, 0.05wt% to 0.5wt% of Mg, 0.05wt% to 0.15wt% of Ti and unavoidable impurities of which the single weight is less than 0.05wt% and the total weight is less than 0.15 wt%.

According to some embodiments, the first skin and the second skin are both 4 series and MOD aluminum alloy thereof, wherein the weight ratio of each element contained in the first skin and the second skin is: 5 to 15 weight percent of Si, 0.05 to 2.0 weight percent of Mg, less than or equal to 0.2 weight percent of Bi and single weight less than 0.05 weight percent and total weight less than 0.15 weight percent of unavoidable impurities.

According to some embodiments, the preparing the core material, the first skin material, and the second skin material comprises:

and carrying out homogenizing annealing treatment on the core material at 550-650 ℃ for 5-15 h.

According to some embodiments, the step of stacking the core material between the first skin material and the second skin material for compounding, before obtaining the aluminum alloy composite ingot, further comprises the steps of:

and respectively carrying out sawing treatment, surface milling treatment and hot rolling treatment on the core material and the first leather and the second leather.

According to some embodiments, the rolling treatment of the aluminum alloy composite ingot to obtain the O-state strip foil further comprises the following steps:

and carrying out preheating treatment at 450-550 ℃ on the aluminum alloy composite ingot, and preserving heat for 2-10 h.

According to some embodiments, the rolling treatment of the aluminum alloy composite ingot to obtain an O-state strip foil comprises:

carrying out hot rolling treatment on the aluminum alloy composite ingot to obtain a hot rolled blank;

carrying out cold rolling treatment on the hot-rolled blank and coiling to obtain a cold-rolled coil;

performing intermediate annealing treatment on the cold-rolled coil to obtain an O-state strip foil;

according to some embodiments, said pre-deforming said O-state foil by 0.5% to 5% higher than said critical deformation comprises:

and when the preset deformation is 0.4-6%, stretching the O-state strip foil in stretch bending straightening equipment.

According to some embodiments, said pre-deforming said O-state foil by 0.5% to 5% higher than said critical deformation further comprises:

and when the preset deformation is 6-15%, rolling the O-state strip foil on a rolling mill with small rolling reduction.

According to some embodiments, the low temperature stress relief annealing of the pre-deformed O-state ribbon foil comprises:

and carrying out low-temperature stress relief annealing at 50-360 ℃ on the pre-deformed O-state strip foil which is 0.5% -5% higher than the critical deformation.

The oil cooler chip material prepared by the preparation method of the oil cooler chip material can be stably produced in mass, can effectively reduce material corrosion, has higher corrosion resistance and reduces leakage risk.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

Fig. 1 shows a schematic structural diagram of an oil cooler chip material prepared according to an example embodiment of the present application.

Fig. 2 shows a flow chart of a method of manufacturing an oil cooler chip material according to an example embodiment of the present application.

Fig. 3 illustrates a flow chart of a method of preparing an oil cooler chip material according to some embodiments of the present application.

FIG. 4a shows a schematic view of the degree of ablation of the O-state foil prepared in example 1.

Fig. 4b shows a schematic view of the degree of corrosion of the oil cooler chip material prepared in example 1.

FIG. 5a shows a schematic view of the degree of ablation of the O-state foil prepared in example 2.

Fig. 5b shows a schematic view of the degree of corrosion of the oil cooler chip material prepared in example 2.

Detailed Description

The following detailed description of the present application is provided in connection with the accompanying drawings and examples in order to provide a better understanding of the aspects of the present application and advantages thereof. However, the detailed description and examples set forth below are for illustrative purposes only and are not intended to be limiting of the present application.

According to the technical conception of the application, the critical deformation of the chip alloy is found, and then the chip alloy is subjected to pre-deformation slightly larger than the critical deformation. At this time, the material is subjected to pre-deformation treatment which is larger than a critical value, and then is subjected to stamping deformation again, so that the melting degree is at a lower level, and the melting degree is not obviously increased.

Therefore, the preparation method of the oil cooler chip material improves the preparation process of the core material and the skin material, the prepared oil cooler chip material can be stably and quantitatively produced, the material corrosion can be effectively reduced, the corrosion resistance is higher, and the leakage risk is reduced.

Hereinafter, a method for manufacturing an oil cooler chip material according to an embodiment of the present application will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, the oil cooler chip material prepared by the method provided by the application consists of a core material 1, and a first skin material 2 and a second skin material 3 which are positioned on the upper layer and the lower layer of the core material. Wherein the first skin material 2 and the second skin material 3 are used as brazing filler metal.

According to some embodiments, the thickness of each skin layer is 0% to 15% of the total thickness of the oil cooler chip material.

According to some embodiments, the core material 1 is a 6-series MOD aluminum alloy, wherein the core material 1 contains the following elements in weight ratio: less than or equal to 1wt% of Si, less than or equal to 0.6wt% of Fe, 0.2wt% to 0.7wt% of Cu, 0.1wt% to 1.5wt% of Mn, 0.05wt% to 0.5wt% of Mg, 0.05wt% to 0.15wt% of Ti and unavoidable impurities of which the single weight is less than 0.05wt% and the total weight is less than 0.15 wt%.

According to some embodiments, the first leather 2 and the second leather 3 are both 4 series and MOD aluminum alloy thereof, and the recombination rate is 0% -15%, wherein the weight ratio of each element contained in the first leather 2 and the second leather 3 is 5% -15% of Si, 0.05% -2.0% of Mg, bi is less than or equal to 0.2% and single unavoidable impurities with the weight less than 0.05% and the total weight less than 0.15%.

According to some embodiments, the first skin 2 and the second skin 3 may be the same alloy or may be different alloys, which is not limited thereto.

The oil cooler chip material prepared by the method improves the preparation process, can be stably produced in mass, can effectively reduce material corrosion, has higher corrosion resistance and reduces leakage risk.

As shown in fig. 2, the preparation method of the oil cooler chip material according to the exemplary embodiment of the present application includes the following steps:

in S201, a core material and a skin material are prepared.

According to an example embodiment, raw materials of elements are added into a smelting furnace according to the components of the core material, the first skin material and the second skin material, and the core material, the first skin material and the second skin material are obtained through smelting.

At S202, the core material and the skin material are composited.

According to an example embodiment, the core material is stacked between the first skin material and the second skin material, and then is compounded to obtain an aluminum alloy composite ingot.

At S203, an O-state tape foil is prepared.

According to an example embodiment, the aluminum alloy composite ingot is subjected to rolling treatment to obtain an O-state strip foil.

At S204, a critical deformation amount is determined.

According to an example embodiment, a critical deformation amount of the O-state foil is determined.

In S205, the pre-deformation process.

According to an exemplary embodiment, the O-state foil is subjected to a pre-deformation that is 0.5% to 5% higher than the critical deformation.

At S206, a stress relief anneal.

According to an example embodiment, the pre-deformed O-state ribbon foil is subjected to a low temperature stress relief anneal.

According to one aspect of the application, in the production process flow of the oil cooler chip material, the elongation of the alloy is improved by performing low-temperature stress relief annealing on the alloy after the pre-deformation.

As shown in fig. 3, the preparation method of the oil cooler chip material according to the exemplary embodiment of the present application includes the following steps:

in S301, a core material and a skin material are prepared.

According to some embodiments, a core material, a first skin material and a second skin material are prepared by casting, wherein the core material is 6 series and MOD aluminum alloy thereof, and the first skin material and the second skin material are 4 series and MOD aluminum alloy thereof;

according to some embodiments, raw materials of elements are added into a smelting furnace according to the components of the core material, the first skin material and the second skin material, and the core material, the first skin material and the second skin material are obtained through melting, electromagnetic stirring, slag skimming, degassing, refining and semi-continuous casting.

According to some embodiments, the smelting process is performed first, the smelting temperature is 745-765 ℃, and the electromagnetic stirring is performed for 2 times, and each time is performed for 10 minutes; then refining is carried out, the refining temperature is 735-755 ℃, and the refining time is 10 minutes; and casting at 700-710 ℃ to obtain the core material, the first skin material and the second skin material.

According to some embodiments, the core material is subjected to homogenization treatment in a homogenization oven, the temperature of the core material is 550-650 ℃, and the temperature is kept for 5-15 hours.

Margareta Nylen and A.Wittebrood et al studied the effect of the degree of deformation before brazing on post-braze erosion and found that a critical value exists. When the deformation amount is smaller than the critical deformation amount, the corrosion degree is increased along with the increase of the deformation amount, and the limit value is reached at the critical deformation amount; after exceeding the critical deformation, the degree of erosion is significantly reduced. The critical value can be obviously moved left by homogenizing the core material, because the pre-stretching influences the recrystallization behavior of the core material, when the critical value is smaller than the pre-stretching behavior, the recrystallization power of the core material is insufficient, and when the critical value is larger than the pre-stretching behavior, the core material is recrystallized; the critical deformation is generally below 10%, and different alloys and processing techniques have different general trends.

At S302, the face is sawed.

And sawing and milling the core material, the first leather and the second leather respectively.

According to some embodiments, the sawing process and the face milling process are performed on the core material, the first skin material and the second skin material, respectively, prior to the compounding operation. Specifically, the head and tail of the core material, the first skin material and the second skin material are respectively cut off by 100-200 mm, the surfaces of the core material, the first skin material and the second skin material are respectively milled, the surface milling quantity of the upper surface and the lower surface is 5-15 mm, and the surface milling quantity of the two side surfaces is 0-10 mm.

At S303, the core material and the skin material are composited.

Stacking the core material with the sawed and milled surface between a first leather material and a second leather material with the sawed and milled surface, and then compounding to obtain a three-layer aluminum alloy composite ingot;

according to some embodiments, the first skin and the second skin are sent into a vertical pushing type heating furnace to be heated, the heating temperature is 460-500 ℃, the heat is preserved for 4-6 hours after the heating is completed, and then the first skin and the second skin are hot rolled to the required thickness. And then, respectively placing the first leather and the second leather on the upper surface and the lower surface of the core material to obtain a three-layer aluminum alloy composite ingot.

Optionally, the thickness of each layer of skin material in the aluminum alloy composite ingot is 0-15% of the thickness of the aluminum alloy composite ingot.

At S304, hot rolling.

And carrying out hot rolling treatment on the aluminum alloy composite ingot to obtain a hot rolled blank.

According to some embodiments, the aluminum alloy composite ingot is subjected to preheating treatment, and then the aluminum alloy composite ingot after the preheating treatment is subjected to hot rolling treatment, so as to obtain a hot rolled blank. Specifically, the temperature of preheating treatment is 450-550 ℃, the heat preservation time is 2-10 h, and then the preheated aluminum alloy composite ingot is subjected to hot rolling treatment until the thickness is 5-10 mm, so that the hot rolled blank is obtained.

At S305, cold rolling.

And carrying out cold rolling treatment on the hot-rolled blank and coiling to obtain a cold-rolled coil.

According to some embodiments, the hot rolled stock is cold rolled to a thickness of 0.2-1.0 and coiled to obtain the cold rolled coil.

At S306, the full recrystallization anneal.

according to some embodiments, the cold rolled coil is annealed in a nitrogen protection heating furnace to obtain a cold rolled strip foil, and the cold rolled strip foil is subjected to complete recrystallization annealing to obtain an O-state strip foil. Specifically, the temperature of the complete recrystallization annealing treatment is 200-500 ℃, and the heat preservation time is 1-10 h.

According to some embodiments, the annealing temperature is controlled to be in the range of 50-80 ℃ above the full recrystallization annealing temperature. In the step, the heat preservation time after annealing is shorter, which is favorable for full and uniform recrystallization inside and outside the aluminum foil coil and avoids the defect of uneven performance caused by overlarge recrystallization size difference due to difference of inside and outside temperature rise.

In S307, a critical deformation amount is determined.

And determining the critical deformation of the O-state tape foil.

According to some embodiments, a sample of the O-state foil after complete recrystallization is taken, checked in the laboratory, and analyzed for critical deformation of the O-state foil.

At S308, the pre-deformation process.

And pre-deforming the O-state belt foil by 0.5-5% higher than the critical deformation.

According to some embodiments, when the preset deformation is 0.4-6%, stretching the O-state strip foil in stretch bending straightening equipment; and when the preset deformation is 6-15%, rolling the O-state strip foil on a rolling mill with small rolling reduction.

At S309, the stress relief anneal.

And carrying out low-temperature stress relief annealing on the O-state strip foil subjected to the pre-deformation treatment to obtain the oil cooler chip material.

According to some embodiments, the pre-deformed O-state strip foil is subjected to low-temperature stress relief annealing to improve elongation and obtain the oil cooler chip material. Wherein the low-temperature annealing treatment temperature is 50-360 ℃.

According to one aspect of the application, in the production process flow of the oil cooler chip material, the critical deformation of the material is detected through a laboratory, then the completely recrystallized material is subjected to the pre-deformation treatment of critical deformation plus (0.5-5)% and then is subjected to the pre-deformation treatment which is larger than the critical value, the subsequent client side performs punching deformation again, the melting degree is at a lower level, no obvious increase exists, and therefore the requirement of improving the corrosion resistance is met.

Example 1

1. And smelting to prepare a core material and a skin material, wherein the compositions of the core material and the skin material are shown in table 1, and the raw materials of each element are respectively placed in a smelting furnace for smelting to obtain the core material and the skin material.

TABLE 1 composition of core and skin materials

Adding raw materials of each element into a smelting furnace according to the components of the core material and the skin material, firstly, smelting at 745-765 ℃ for 2 times of electromagnetic stirring, and stirring for 10 minutes each time; then refining is carried out, the refining temperature is 735-755 ℃, and the refining time is 10 minutes; casting at 700-710 deg.c to obtain flat cast ingot of core material and skin material of 450mmx1290mmx5000 mm.

2. Homogenizing the cast ingot in a homogenizing furnace, heating to 550 ℃, and preserving heat for 10 hours.

3. Sawing the cast ingot according to the specification requirement, and cutting the head and the tail by 100mm respectively; milling the surface, wherein the milling quantity of the upper surface and the lower surface is 10mm, and the milling quantity of the small surfaces on two sides is 5mm.

4. Preheating the leather ingot after sawing and milling the surface, wherein the preheating temperature is between 500 ℃, and the heat preservation time is 2 hours; and then hot-rolling the preheated skin ingot to the thickness of 65 mm+/-2 mm to obtain hot-rolled plates of the skin 1 and the skin 2.

5. And compounding the prepared skin material and the core material, wherein the skin material 1 and the skin material 2 respectively account for 11 percent.

6. Preheating the compounded alloy composite ingot, wherein the preheating temperature is between 500 ℃, and the heat preservation time is 2 hours; and then hot-rolling the preheated composite ingot to a thickness of 5mm to obtain a hot-rolled plate strip.

7. The hot rolled material was cold rolled to a coil thickness of 0.4mm in multiple passes.

8. And (3) annealing the cold-rolled coil in a nitrogen protection heating furnace, and performing complete recrystallization annealing on the cold-rolled strip foil, wherein the annealing temperature is 380 ℃, and the heat preservation time is 2 hours, so as to obtain the O-state strip foil.

9. Taking the completely recrystallized O-state strip foil, and checking in a laboratory to analyze the critical deformation of the alloy by 2.5%; as shown in fig. 4a, the O-state foil was subjected to simulated brazing after laboratory pre-deformation to find a critical deformation of 2.5%.

10. Processing the annealed O-state strip foil with a small rolling reduction of 2.5% +2% of critical deformation; stretching is carried out in stretch bending straightening equipment, and the preset deformation is 4.5%.

11. Carrying out low-temperature stress relief annealing on the alloy after the pre-deformation, wherein the annealing temperature is 290 ℃, and preserving heat for 2 hours; the elongation after stress relief annealing is improved from 15% to 20%; and carrying out deformation treatment of the annealed material to different degrees, respectively carrying out simulated brazing on the deformed material to different degrees, and detecting corrosion, wherein the corrosion of the material is at a lower level at the moment, as shown in fig. 4 b.

Example 2

1. And smelting to prepare a core material and a skin material, wherein the compositions of the core material and the skin material are shown in table 2, and the raw materials of each element are respectively placed in a smelting furnace for smelting to obtain the core material and the skin material.

TABLE 2 composition of core and sheath materials

4. Preheating the leather ingot after sawing and milling the surface, wherein the preheating temperature is between 500 ℃, and the heat preservation time is 2 hours; and then hot-rolling the preheated skin ingot to the thickness of 65+/-2 mm to obtain hot-rolled plates of the skin 1 and the skin 2.

7. The hot rolled material was cold rolled to a coil thickness of 0.5mm in multiple passes.

9. Taking the completely recrystallized O-state strip foil, and checking in a laboratory to analyze the critical deformation of the alloy by 5%; as shown in fig. 5a, the O-band foil was subjected to simulated brazing corrosion after laboratory pre-deformation to find a critical deformation of 5%.

10. Processing the annealed O-state strip foil with a small rolling reduction of 5% +3% of critical deformation; rolling on a rolling mill, and presetting the deformation amount to 8%.

11. Carrying out low-temperature stress relief annealing on the alloy after the pre-deformation, wherein the annealing temperature is 290 ℃, and preserving heat for 2 hours; the elongation after stress relief annealing is improved from 13% to 18%; and carrying out deformation treatment of the annealed material to different degrees, respectively carrying out simulated brazing on the deformed material to different degrees, and detecting corrosion, wherein the corrosion of the material is at a lower level at the moment, as shown in fig. 5 b.

In conclusion, the oil cooler chip material prepared by the method improves the preparation process, and the prepared oil cooler chip material can be stably produced in mass, can effectively reduce material corrosion, has higher corrosion resistance and reduces leakage risk.

Finally, it should be noted that: it is apparent that the above examples are only illustrative of the present invention and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims

1. A method for preparing an oil cooler chip material, the method comprising:

preparing a core material, a first skin material and a second skin material, wherein the core material comprises the following elements in parts by weight: less than or equal to 1wt% of Si, less than or equal to 0.6wt% of Fe, 0.2wt% to 0.7wt% of Cu, 0.1wt% to 1.5wt% of Mn, 0.05wt% to 0.15wt% of Mg, 0.05wt% to 0.15wt% of Ti and unavoidable impurities of which the single weight is less than 0.05wt% and the total weight is less than 0.15wt%, wherein the weight ratio of each element contained in the first skin material to the second skin material is as follows: 5 to 15 weight percent of Si, 0.05 to 2.0 weight percent of Mg, less than or equal to 0.2 weight percent of Bi and unavoidable impurities of which the single weight is less than 0.05 weight percent and the total weight is less than 0.15 weight percent;

rolling the aluminum alloy composite ingot to obtain an O-state strip foil;

determining the critical deformation of the O-state tape foil;

pre-deforming the O-state strip foil by 0.5% -5% higher than the critical deformation, stretching the O-state strip foil in stretch bending straightening equipment when the preset deformation is 0.4% -6%, and rolling the O-state strip foil on a rolling mill with small rolling reduction when the preset deformation is 6% -15%;

2. The method of manufacturing according to claim 1, wherein the manufacturing the core material, the first skin material, and the second skin material comprises:

3. The method of manufacturing according to claim 1, wherein the step of laminating the core material between the first skin material and the second skin material for compounding, before obtaining the aluminum alloy composite ingot, further comprises the steps of:

and carrying out sawing treatment, surface milling treatment and hot rolling treatment on the core material and the first leather and the second leather respectively.

4. The method according to claim 1, wherein the rolling treatment of the aluminum alloy composite ingot to obtain the O-state foil further comprises the following steps:

5. The method of claim 1, wherein the rolling the aluminum alloy composite ingot to obtain an O-state foil comprises:

and carrying out intermediate annealing treatment on the cold-rolled coil to obtain the O-state strip foil.

6. The method of manufacturing according to claim 1, wherein the low temperature stress relief annealing of the pre-deformed O-state ribbon foil comprises: