High Temperature Alloy Castings

High temperature alloy castings is the main product of Zhongwei Precision Machinery Co., Ltd. The company is one of the few domestic enterprises that can mass-produce deformed superalloys, cast superalloy master alloys and superalloy precision castings. The company has advanced special smelting, investment casting, pipe making and other equipment, and has established a whole industry chain production process of special smelting, forging, hot rolling, rolling and casting, and can independently produce high-temperature alloys, precision alloys, special stainless steel and other high Special alloy materials with high performance, and through cold and hot processing technology, a relatively complete product structure such as bars, wires, strips, pipes, castings, etc. has been formed.

Product Description

Basic situation of high temperature alloy castings

1. Implementation standards: The company strictly implements ISO9001 & TS 16949 certification.

2. Product material standards: ISO, GB, ASTM, SAE, ISO, EN, DIN, JIS, BS

3. Main processes: sand casting, silica sol investment casting, water glass investment casting,shell casting,deburring, sand blasting, machining, heat treatment, leak testing, surface treatment, etc.

The company adapts to the market with "specialized, refined and special" product characteristics, and develops the market with differentiated competition and technical services. The company has mastered key core technologies such as ultra-pure smelting of superalloy materials, near-net-shape investment casting, and high-precision seamless pipe manufacturing. ), GH2132 (A286), GH3625 and other deformed superalloy series, a complete product structure of more than 30 varieties of alloy materials and multi-standard casting products.

Defects And Prevention Methods Of Superalloy Castings

In the production of high temperature alloy castings, common defects and their cause analysis and prevention methods can be found as follows:

1. Looseness (microscopic loosening)

A Reason analysis:

(1) The gas content of the alloy liquid is large, and gas is precipitated during solidification, which hinders feeding

(2) The cooling of the casting is too slow, and the dendrites are large, which hinders the feeding

(3) The casting is cooled too fast and it is too late to feed

B prevention method:

(1) Strengthen degassing and degassing, and the vacuum degree of the furnace should be sufficient

(2) Strictly control the pouring temperature

(3) Appropriately increase the shell temperature

2. Shrinkage

A Reason analysis:

(1) The alloy itself has a wide crystallization temperature range. It tends to paste solidification

(2) The gating system and casting structure are not conducive to directional solidification

(3) Improper pouring temperature

(4) The thermal conductivity of the shell material is poor, and the cooling of the casting is slow

B prevention method:

(1) Appropriately adjust the alloy composition to narrow the crystallization temperature range

(2) Improve the casting structure and gating system to facilitate directional solidification

(3) Strictly control the pouring temperature

(4) Improve the pouring method and increase the cooling rate of the casting

3. Slag inclusion

A Reason analysis:

(1) Poor slag making and unclean slag removal

(2) The charge is too dirty

(3) The vacuum degree of the furnace is low

B prevention method:

(1) The surface of the ingot should be cleaned, and it is best to use it after "peeling"

(2) Use ceramic filter to block slag

4. Oxidation of slag inclusions

A Reason analysis:

(1) The charge is not clean, the smelting and pouring operation is improper, and there are many oxides in the molten metal.

(2) The alloy liquid reacts with the crucible wall or shell material

B prevention method:

(1) Select clean charge, preferably after sandblasting or drum cleaning

(2) Carefully clean the crucible

(3) Select crucible materials and shell materials with good chemical stability

5. Chemical sticky sand

A Reason analysis:

(1) There are many oxides in the alloy liquid

(2) Serious reaction between alloy liquid and shell material

(3) Improper selection of shell material, or inappropriate paint ratio

(4) The pouring temperature is too high

B prevention method:

(1) Strictly implement the melting and casting process to reduce oxides

(2) Select suitable shell materials, and the impurity content should be low

(3) Appropriately reduce the pouring temperature and the shell preheating temperature

5. Oxide Scar

A Reason analysis: Before the vacuum furnace remelting, the mother alloy ingot was not ground or cleaned

B prevention method: the master alloy must be "peeled" before use to remove the surface oxide layer

6. Air holes

A Reason analysis:

(1) The charge is not clean

(2) Inappropriate smelting process, insufficient deoxidation and degassing

(3) The pouring temperature is too high

B prevention method:

(1) The charge should be cleaned and the surface should be clean

(2) Control the superheating temperature and time of the alloy liquid, and fully deoxidize and degas

(3) Strictly control the pouring temperature

7. Thermal cracking

A Reason analysis:

(1) The solidification interval of the alloy is large or there are many inclusions in the alloy liquid

(2) The wall thickness difference of the casting is large, and the gating system is unreasonable

(3) Poor concession of shell or core

(4) The casting temperature is low and the pouring temperature is high

B prevention method:

(1) The alloy should be selected reasonably, the charge should be clean, and the smelting process should be appropriate

(2) Improve the casting design. Adopt reasonable gating system to reduce casting shrinkage resistance

(3) Select the appropriate shell material or add appropriate amount of additives to improve its concessionality

(4) Master the appropriate pouring process

Post Casting Process

1. Heat treatment: annealing, carbonization, tempering, quenching, normalizing, surface tempering

2. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

3. Surface treatment: powder spraying, chrome plating, painting, sandblasting, nickel plating, galvanizing, blackening, polishing, bluing, etc.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam).

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements

3. Testing equipment: flaw detection, spectrum analyzer, golden image analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine;

4. Provide after-sales service.

5. The quality can be traced back.

Application

High temperature alloy castings are widely used in aerospace industry, electric power, automobile, metallurgy, glass manufacturing, atomic energy and other industrial fields. Aerospace and electric power are the main downstream of superalloy (more than 70%). In addition to aero engines and naval gas turbines, superalloys are also widely used in aerospace engines, gas turbines, automotive turbocharging, nuclear power, petrochemicals, metallurgy

Gold production, textile, glass manufacturing and many other civilian fields.

Superalloys have been used in aircraft engines since their birth. In modern aircraft engines, the amount of superalloy materials is used.

It accounts for 40% to 60% of the total weight of the engine, and is mainly used for the four hot end components: combustion chamber, guide, turbine blade and turbine disk. In addition, it is also used for casing, ring, afterburner and tail nozzle. and other parts. The progress of the engine is mainly determined by its thrust-to-weight ratio index, and to make the aviation gas turbine engine achieve high performance with small size and light weight.

The measure is to use higher gas temperature. When the turbine inlet temperature increases by 100℃, the thrust-weight ratio of the aero-engine can be increased by about 10%. At present, the average temperature of the turbine inlet of the most advanced fourth-generation engines with a thrust-to-weight ratio of 10 in foreign countries has reached about 1600°C.

Gas turbines are another main use of superalloys, and light-duty gas turbines are mainly used for power peak regulation and ship power. Heavy-duty gas turbines are industrial gas turbines mainly used for combined cycle power generation and cogeneration. The temperature of the gas injected into the impeller by the gas turbine is as high as 1300 ℃, so the impeller needs to be made of superalloy. At present, my country spends hundreds of millions of dollars on imported turbine blade spare parts every year. The development prospects of domestic gas turbines provide a huge space for the use of superalloys.