Casting vacuum heat treatment process

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Preparation before operation

1 Check whether the thermocouples and thermometers are normal.

2 Check whether the electrical switches, circuits and meters are normal.

3.Check the status of the kiln body, kiln door and kiln car to see if they are normal.

4.The operator specifies the name, quantity, material and process curve of the heat-treated castings in this kiln.

Operation process

1 Casting and test piece kiln

2 The castings after cleaning should be confirmed by the inspectors, and the kiln installation mark record should be written before the kiln can be installed.

3 Castings of the same material and different heats are allowed to be processed in the same kiln, but the castings of the same heat are placed separately and cannot be mixed, and there is a certain gap between the castings. The castings are laid flat and fastened to prevent deformation during heat treatment. According to the power and load of the heat treatment kiln, the loading amount is determined, and overloading is strictly prohibited.

4 After the castings are installed in the kiln, according to the heats of the castings, the test rods are loaded into the furnace.

5The kiln location of the test rod should be able to better represent the vacuum heat treatment condition of the casting.

kiln

According to the casting material grade, select or set the vacuum heat treatment process curve. After the process parameters are set, check the kiln temperature and curve records at any time to ensure that the curve records meet the process requirements.

2ZG230-450 steel castings are normalized according to the following heat treatment curve:

B and C grade steel castings are carried out according to the following vacuum heat treatment curves:

The quenching and tempering treatment of grade E steel is carried out in a continuous belt furnace, and the vacuum quenching + tempering is carried out according to the following process curve:

Cleaning and welding repairs after heat treatment of castings.

unloading the kiln

After pulling the kiln, check the outer parts of the casting. If there are obvious heat treatment defects, it should be investigated and dealt with in time with the technical inspector, otherwise the kiln should not be unloaded.

B-grade steel, C-grade steel and E-grade steel castings are drawn from each kiln with 2 pieces of each type, and two pieces of hook tongues drawn from each smelting furnace of the coupler are all tested for physical hardness. Batch castings are checked one by one.

Take down the test pieces, check the quantity, and send the test pieces to the designated person for physical and chemical inspection.

Quenching and tempering control, coupler, yoke and yoke are heated by continuous heat treatment furnace.

For each smelting furnace secondary casting, the first piece into the heat treatment kiln must enter the kiln at the same time as the furnace test piece.

Vacuum quenching to vacuum tempering should be carried out continuously, and should not exceed 8 hours in special cases.

Hook tail surface hardening requirements

The traction arc surface of the coupler hook tail pin hole adopts the flame surface quenching process, and the end face of the hook tail adopts the medium frequency induction heating quenching process.

Before surface quenching, use a baking gun or a wind (electric) grinding wheel to polish the quenched surface to remove oxide scale and residual sand.

After the surface of the hook tail is quenched, the casting should be tempered at low temperature, the tempering temperature is 220~250℃, and the tempering time is 2~3 hours.

Equipment selection: The RVGQ series vacuum heat treatment furnace produced by SIMUWU is a high-quality product for the vacuum heat treatment of tooling and molds. The good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum heat treatment process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum tempering furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.