CN114439590A - High temperature resistant exhaust pipe and preparation method thereof - Google Patents

Abstract

The invention discloses a high-temperature-resistant exhaust pipe and a preparation method thereof, wherein the high-temperature-resistant exhaust pipe comprises an exhaust pipe main pipe made of a high-temperature-resistant alloy material, an exhaust pipe branch pipe is communicated with the exhaust pipe main pipe, the exhaust pipe main pipe and the exhaust pipe branch pipe are integrally cast, the connecting part between the exhaust pipe branch pipe and the exhaust pipe main pipe comprises an outer corner part arranged at an obtuse angle and an inner corner part arranged at an acute angle, a reinforcing alloy sheet is embedded in the inner corner part, the width extension direction of the reinforcing alloy sheet is consistent with the thickness direction of the section of the inner corner part, and the inner contour and the outer contour of the reinforcing alloy sheet are respectively adaptive to the inner contour and the outer contour of the inner corner part. The invention reduces the generation of cracks, ensures the normal work of the exhaust pipe and prolongs the service life of the exhaust pipe.

Description

High temperature resistant exhaust pipe and preparation method thereof

technical field

The invention relates to the field of engine parts manufacturing, in particular to a high temperature resistant exhaust pipe and a preparation method thereof.

Background technique

At present, the production of engine exhaust pipes is mainly made of cast iron materials. When the engine is working, the exhaust pipe is in direct contact with the high-temperature gas, and the working temperature can reach about 700°C or even higher. Under high temperature, cracks often occur due to thermal fatigue at the fillet between the exhaust branch pipe and the exhaust main pipe and the connection between the root of the exhaust branch pipe and the flange, resulting in the cracking of the exhaust pipe.

The patent document whose document number is CN103725949A discloses the production method of high Ni austenitic ductile iron exhaust pipe, wherein the production flow and the technological method are as follows: the first step: charge ratio, the second step: melting, the third step: ball Chemical treatment, the fourth step: pouring. In the third step, the spheroidizing treatment of austenitic ductile iron is carried out by the "sandwich method", that is, the spheroidizing agent is first put into the spheroidizing dam, and after it is flattened, the inoculant is covered on the spheroidizing dam. Finally, the steel plate is used to cover the inoculant. The amount of nodulizer added is 0.8% of the liquid weight, and the amount of inoculant added is 1.2% of the liquid weight. The "sandwich method" is used for processing, and the amount of nodulizer added is 0.8% of the liquid weight, and the added amount of the inoculant is 1.2% of the liquid weight. In the pouring process of the fourth step, heat preservation risers are arranged in the thick parts of the casting, especially in the thick flange parts. In the fourth step of the pouring process, a process cold iron is provided at the hot joint of the casting. The disadvantage is that there are problems of stress concentration and insufficient high temperature resistance strength at the connection part of the exhaust branch pipe and the exhaust main pipe.

SUMMARY OF THE INVENTION

The first technical problem to be solved by the present invention is to provide a high temperature resistant exhaust pipe. From the perspective of composite materials, a high temperature resistant alloy sheet is embedded in the position where the exhaust pipe is easy to crack during the casting process, so as to reduce the cracking of the exhaust pipe. risk and prolong the service life of the engine exhaust pipe.

In order to solve the above-mentioned technical problems, the provided high temperature exhaust pipe includes an exhaust pipe main pipe made of high temperature alloy material, the exhaust pipe main pipe is connected with an exhaust pipe branch pipe, the exhaust pipe main pipe and the exhaust pipe branch pipe. It is integrally cast and formed, and the connection part between the exhaust pipe branch pipe and the exhaust pipe main pipe includes an outer corner part arranged at an obtuse angle and an inner corner part arranged at an acute angle. The width extension direction of the reinforcing alloy sheet is consistent with the thickness direction of the cross-section of the inner corner, and the inner and outer contours of the reinforcing alloy sheet are adapted to the inner and outer contours of the inner corner respectively.

Two sides of the inner corner are symmetrically embedded with reinforced alloy sheets.

A plurality of protrusions are densely distributed on the reinforcing alloy sheet.

The plurality of protrusions respectively protrude toward two surfaces of the reinforcing alloy sheet, and the other surface of the reinforcing alloy sheet corresponding to the protrusion is concave.

The reinforcing alloy sheet is also connected with a convex column fused with the inner corner.

After the above structure is adopted, since the reinforced alloy sheet of the above structure is embedded in the inner corner, the maximum thermal stress of the inner corner of the exhaust pipe during operation is much smaller than the yield strength of the reinforced alloy sheet, thereby reducing the generation of cracks and ensuring the exhaust pipe. The normal operation of the trachea extends the service life of the exhaust pipe. The protrusions and the protruding column structures of the above structures can ensure fusion during casting and ensure the quality of the exhaust pipe.

The second technical problem to be solved by the present invention is to provide a preparation method of a high temperature resistant exhaust pipe, which comprises the following steps:

1) Use molding sand to make the exhaust pipe mold blank, which includes an outer mold and an inner cavity core mold;

2) The reinforced alloy sheet is made of nickel-based superalloy, and the reinforced alloy sheet is provided with a connecting column, the connecting column is connected to the inner corner of the inner cavity core mold, and the connecting column is provided with an easy-to-break section;

3) Assemble the inner cavity core mold and the outer mold after installing the reinforced alloy sheet to form a mold box;

4) Put the high temperature fatigue strength material in molten state into the mold box;

5) After the exhaust pipe casting in the mold box is fully cooled, open the mold box and take out the exhaust pipe casting;

6) Clean the protruding connecting post on the exhaust pipe casting to form the exhaust pipe.

In step 2), the nickel-based superalloy includes nickel as the matrix, and is composed of γ-phase and γ'-phase austenite and carbides.

In step 2), the connecting column is connected to one side or both inner and outer surfaces of the reinforcing alloy sheet, and the cross-sectional area of the easy-to-break section is much smaller than the cross-sectional area of the connecting column.

The reinforcing alloy sheet is densely covered with a plurality of protrusions, the plurality of protrusions respectively protrude toward two surfaces of the reinforcing alloy sheet, and the other surface of the reinforcing alloy sheet corresponding to the protrusion is a concave surface.

The outer surface of the reinforced alloy sheet is higher than the outer surface of the inner cavity core mold, and the distances between the inner and outer surfaces of the reinforced alloy sheet from the inner and outer surfaces of the inner corner are 1/6-1/8 of the thickness of the inner corner.

After the above method is adopted, a high-quality exhaust pipe with a long service life can be quickly produced, and the risk of cracks in the exhaust pipe can be reduced.

Description of drawings

Below in conjunction with accompanying drawing, the present invention is further described:

1 is a schematic structural diagram of an embodiment of the present invention;

Fig. 2 is the structural representation of the top view of Fig. 1;

Fig. 3 is the enlarged view of A district among Fig. 2;

4 is a schematic structural diagram of an embodiment of a reinforcing alloy sheet in the present invention;

5 is a schematic structural diagram of another embodiment of the reinforced alloy sheet in the present invention;

FIG. 6 is a schematic perspective view of FIG. 5 .

Detailed ways

As shown in Figures 1 and 2, Figure 1 shows a high temperature resistant exhaust pipe of an engine. There are many types of exhaust pipes of an engine. Here, one type of exhaust pipe is used as an example for description. , which includes an exhaust pipe main pipe 1 made of a high temperature resistant alloy material, the high temperature resistant alloy material adopts silicon molybdenum vermicular iron, silicon molybdenum ductile iron or high-nickel ductile iron in the prior art, etc., and the exhaust pipe main pipe 1 is connected to There is an exhaust pipe branch pipe 2, the exhaust pipe main pipe 1 and the exhaust pipe branch pipe 2 are integrally cast and formed, and the connection part between the exhaust pipe branch pipe 2 and the exhaust pipe main pipe 1 includes an outer corner portion 3 arranged at an obtuse angle and an outer corner portion 3 formed at an obtuse angle. The inner corner portion 4 is arranged at an acute angle. The inner corner portion 4 is embedded with a reinforcing alloy sheet 5. The width extension direction of the reinforcing alloy sheet 5 is consistent with the thickness direction of the cross-section of the inner corner portion 4. The inner contour of the reinforcing alloy sheet 5 The outer contour is adapted to the inner and outer contours of the inner corner portion 4 respectively. Specifically, the two sides of the above-mentioned inner corner portion 4 are symmetrically embedded with reinforcing alloy sheets 5. The above-mentioned inside and outside refer to the inner and outer sides in FIG. The advantage of the above structure is that after the reinforcing alloy sheet 5 and the exhaust pipe branch pipe 2 are integrally cast and formed, it can fully ensure that the inner corner part where the thermal stress is concentrated is not prone to cracking and prolongs the service life of the exhaust pipe.

Referring to the drawings, the reinforcing alloy sheet 5 is densely covered with a plurality of protrusions 6, the plurality of protrusions 6 respectively protrude toward the two surfaces of the reinforcing alloy sheet 5 and the other surface of the reinforcing alloy sheet corresponding to the protrusion is concave, That is to say, both surfaces of the reinforcing alloy sheet 5 are provided with protrusions and concave surfaces, and the reinforcing alloy sheet is also connected with a convex column 7 fused with the inner corner. The fusion degree of the inner corner 4 during casting ensures the casting fusion performance of the two materials. The arrangement of the above-mentioned convex columns can not only serve as a support to ensure the embedded casting position of the reinforcing alloy sheet 5, but also further strengthen the combination of the two materials. Figures 3 and 4 show two specific embodiments of the reinforced alloy sheet 5, which have different connection structures (that is, in the process of insert casting, the fixing method of the reinforced alloy sheet is different). The connecting column is connected on one side or on the inner and outer surfaces, and the connecting column is provided with an easy-to-break section. The cross-sectional area of the easy-to-break section is much smaller than the cross-sectional area of the connecting column. The folded section is broken, and the section still remaining on the reinforcing alloy sheet forms the said stud.

Referring to the drawings, the present invention also provides a method for preparing a high temperature resistant exhaust pipe, comprising the following steps: 1) using molding sand to make an exhaust pipe mold blank, the exhaust pipe mold blank includes an outer mold and an inner cavity core mold ;2) Using nickel-based superalloy to make reinforced alloy sheets, the reinforced alloy sheets are provided with connecting columns, the connecting columns are connected to the inner corners of the inner cavity core mold, and the connecting columns are provided with easy-to-break sections; 3) Install the reinforced alloy The inner cavity core mold after the film is assembled with the outer mold to form a mold box; 4) Put the high temperature fatigue strength material in the molten state into the mold box; 5) After the exhaust pipe casting in the mold box is fully cooled, open the mold box , take out the exhaust pipe casting; 6) Clean the protruding connecting column on the exhaust pipe casting to form an exhaust pipe.

In the above step 2), the nickel-based superalloy includes nickel as the matrix, and is composed of γ-phase and γ'-phase austenite and carbide, and one side or the inner and outer surfaces of the reinforced alloy sheet are connected with In the connecting column, the cross-sectional area of the frangible section is much smaller than the cross-sectional area of the connecting column. The reinforcing alloy sheet is densely covered with a plurality of protrusions, the plurality of protrusions respectively protrude toward two surfaces of the reinforcing alloy sheet, and the other surface of the reinforcing alloy sheet corresponding to the protrusion is a concave surface. The outer surface of the reinforced alloy sheet is higher than the outer surface of the inner cavity core mold, and the distances between the inner and outer surfaces of the reinforced alloy sheet from the inner and outer surfaces of the inner corner are 1/6-1/8 of the thickness of the inner corner.

Referring to the drawings, from the perspective of composite materials, high-temperature alloy sheets are inlaid at the position where the exhaust pipe is easy to crack during the casting process. Most of the existing superalloy sheets are nickel-based superalloys. Nickel-based superalloys are based on Ni and are usually composed of γ phase, γ‛ phase and carbide. A class of alloys with comprehensive properties such as certain oxidation resistance and corrosion resistance; there are many elements in nickel-based superalloys, including more than 20 alloying elements such as Cr, Al, Ti and Co, most of which can produce second-phase strengthening and solid-solution strengthening. Nickel-based superalloys have high high temperature strength, as well as strong oxidation resistance, thermal fatigue resistance and thermal corrosion resistance. Taking nickel-based superalloy M951G as an example, its yield strength at 700-800℃ is between 835-860Mpa, and the local maximum thermal stress of the exhaust pipe is much smaller than the yield strength of nickel-based superalloy, thereby reducing cracks. It is generated, which ensures the normal operation of the exhaust pipe and prolongs the service life of the exhaust pipe.

As shown in the accompanying drawings, the present invention also provides a specific embodiment of a high temperature resistant exhaust pipe and a preparation method thereof. A high temperature resistant exhaust pipe is provided on the X-type engine, which includes An exhaust pipe main pipe 1 is formed. The exhaust pipe main pipe 1 is connected with an exhaust pipe branch pipe 2. The exhaust pipe main pipe 1 and the exhaust pipe branch pipe 2 are integrally cast and formed. The exhaust pipe branch pipe 2 and the exhaust pipe main pipe 1 are formed by casting. The connection part includes an outer corner part 3 arranged at an obtuse angle and an inner corner part 4 arranged at an acute angle. The inner corner part 4 is embedded with a reinforced alloy sheet 5, and the width extension direction of the reinforced alloy sheet 5 and the thickness of the section of the inner corner 4 In the same direction, the inner and outer contours of the reinforced alloy sheet 5 are adapted to the inner and outer contours of the inner corner portion 4 respectively. The reinforced alloy sheet is densely covered with a plurality of protrusions, and the plurality of protrusions respectively protrude toward the two surfaces of the reinforced alloy sheet and The other surface of the reinforcing alloy sheet corresponding to the protrusion is a concave surface, and the reinforcing alloy sheet is also connected with a convex column fused with the inner corner. In the insert casting process, the distance between the reinforcing alloy sheet and the inner and outer surfaces of the casting is 1/6~1/8 of the wall thickness of the casting, the wall thickness of the casting is 7 mm, and the distance between the reinforcing alloy sheet and the inner and outer surfaces of the casting is about 1 mm, and the wall thickness of the alloy sheet is about 1 mm. It is 1~2mm, and the reinforcing alloy sheet 5 is fixed on the sand core/mold by the connecting rod. There is a breakable section on the upper part, and the position of the breakable section is located on the inner and outer surfaces of the casting, which is convenient for removing the fixing rod during the cleaning stage of the casting; the connecting rod of the vertical structure in Figure 5 can also be used, and the diameter of the connecting rod is 1.5mm ~2.5mm, there is a breakable section on the top, and the position of the breakable section is located on the inner and outer surfaces of the casting, which is convenient for removing the fixing rod during the cleaning stage of the casting. The reinforced alloy sheet can be made with the sand core during the core making process; the process hole can also be reserved on the sand core/mold, and the fixed section of the reinforced alloy sheet can be inserted into the process hole when molding or core setting. fixed.

The present invention is not limited by the above-mentioned embodiments, and for those skilled in the art, equivalent changes based on the specific structures of the present invention and simple replacement of method steps are all within the protection scope of the present invention.

Claims (10)

1. A high temperature resistant exhaust pipe, comprising an exhaust pipe main pipe made of a high temperature resistant alloy material, an exhaust pipe branch pipe is communicated with the exhaust pipe main pipe, and the exhaust pipe main pipe and the exhaust pipe branch pipe are integrally cast and formed, and the The connection part between the branch pipe of the exhaust pipe and the main pipe of the exhaust pipe includes an outer corner part arranged at an obtuse angle and an inner corner part arranged at an acute angle, and it is characterized in that: the inner corner part is embedded with a reinforced alloy sheet, and the width of the reinforced alloy sheet is The extending direction is consistent with the thickness direction of the section of the inner corner, and the inner and outer contours of the reinforcing alloy sheet are adapted to the inner and outer contours of the inner corner respectively. 2 . The high temperature resistant exhaust pipe according to claim 1 , wherein the inner corners are symmetrically embedded with reinforcing alloy sheets on both sides. 3 . 3. The high temperature resistant exhaust pipe according to claim 1 or 2, wherein a plurality of protrusions are densely distributed on the reinforcing alloy sheet. 4 . The high temperature resistant exhaust pipe according to claim 3 , wherein the plurality of protrusions respectively protrude toward the two surfaces of the reinforcing alloy sheet and the other surface of the reinforcing alloy sheet corresponding to the protrusion is concave. 5 . 5 . The high temperature resistant exhaust pipe according to claim 1 or 2 , wherein the reinforcing alloy sheet is further connected with a convex column fused with the inner corner. 6 . 6. A preparation method of a high temperature resistant exhaust pipe, comprising the following steps: 1) Use molding sand to make the exhaust pipe mold blank, which includes an outer mold and an inner cavity core mold; 2) The reinforced alloy sheet is made of nickel-based superalloy, and the reinforced alloy sheet is provided with a connecting column, the connecting column is connected to the inner corner of the inner cavity core mold, and the connecting column is provided with an easy-to-break section; 3) Assemble the inner cavity core mold and the outer mold after installing the reinforced alloy sheet to form a mold box; 4) Put the high temperature fatigue strength material in molten state into the mold box; 5) After the exhaust pipe casting in the mold box is fully cooled, open the mold box and take out the exhaust pipe casting; 6) Clean the protruding connecting post on the exhaust pipe casting to form the exhaust pipe. 7 . The method for preparing a high temperature resistant exhaust pipe according to claim 6 , wherein in step 2), the nickel-based superalloy comprises nickel as a matrix, and is composed of γ-phase and γ′-phase austenite, carbonized composition. 8 . The method for preparing a high temperature resistant exhaust pipe according to claim 6 , wherein in step 2), the connecting column is connected to one side or both inner and outer surfaces of the reinforcing alloy sheet, and the The cross-sectional area of the frangible section is much smaller than that of the connecting column. 9 . The method for manufacturing a high temperature resistant exhaust pipe according to claim 6 , wherein the reinforcing alloy sheet is densely covered with a plurality of protrusions, and the plurality of protrusions respectively protrude toward the two surfaces of the reinforcing alloy sheet and correspond to the protrusions. 10 . The other surface of the reinforced alloy sheet is concave. 10 . The method for preparing a high temperature resistant exhaust pipe according to claim 6 , wherein the outer surface of the reinforced alloy sheet is higher than the outer surface of the inner cavity core mold, and the inner and outer surfaces of the reinforced alloy sheet are respectively separated from the inner and outer surfaces. 11 . The distance between the inner and outer surfaces of the inner corner is 1/6-1/8 of the thickness of the inner corner.

Images