Forging process of stainless steel plate

2025-03-04

Stainless steel plate because of its excellent corrosion resistance, high strength and beautiful surface, widely used in construction, home appliances, transportation, industrial equipment and other fields. As one of the key processes of stainless steel plate manufacturing, forging directly affects its mechanical properties and surface quality. This paper will discuss the forging process of stainless steel plate in detail, covering material selection, heating, forging process, heat treatment, surface treatment, quality inspection and subsequent processing.

1. Material preparation

1.1 Types of stainless steel
Stainless steel can be divided into many types according to its chemical composition and microstructure, common ones are:
Austenitic stainless steel: such as 304 and 316, with good corrosion resistance and weldability.
Ferritic stainless steel: such as 430, with high strength and magnetism.
Martensitic stainless steel: such as 410, with high hardness and wear resistance.
Duplex stainless steel: such as 2205, both austenite and ferrite advantages, with high strength and corrosion resistance.
1.2 Material selection
Choosing the right type of stainless steel is the first step in the forging process. According to the application requirements of the final product, stainless steel materials with corresponding mechanical properties and corrosion resistance are selected. For example, 304 or 316 stainless steel plates are usually selected for construction, while industrial equipment may require higher strength duplex stainless steel.
1.3 Blank preparation
The selection and preparation of blank is very important to the forging process. The billet is usually a steel ingot or billet, and its size and shape should be designed according to the requirements of the final product. The surface of the billet should be clean, without cracks, pores and other defects.

2. Heat up

2.1 Heating temperature
The forging temperature of stainless steel is usually between 1000°C and 1250°C. The temperature depends on the type and composition of the stainless steel. High heating temperature may lead to coarse grains and affect mechanical properties. Too low temperature may lead to forging difficulties and cracks.
2.2 Heating Equipment
Commonly used heating equipment includes gas furnaces, electric furnaces and induction furnaces. Gas furnaces are suitable for mass production, while electric furnaces and induction furnaces are suitable for small batch and high-precision production.
2.3 Heating time
The heating time should be adjusted according to the size of the billet and the performance of the heating equipment. Too short heating time may lead to uneven internal temperature of billet and affect forging quality; Too long heating time may lead to coarse grains and waste of energy.

3. Forging process

3.1 Preliminary forging
Initial forging is the process of forming the heated blank. Pressure is applied to the blank by press or hammer forging machine to cause plastic deformation, remove internal defects and improve organizational structure. The goal of early forging is to make the blank close to the final shape while improving its density and uniformity.
3.2 Precision Forging
Precision forging is further machining on the basis of initial forging to achieve the final shape and size. In the process of precision forging, the forging temperature and deformation amount need to be strictly controlled to ensure the surface quality and internal structure of the product. The stainless steel plate after precision forging should have high dimensional accuracy and surface finish.
3.3 Forging Equipment
Commonly used forging equipment includes hydraulic press, mechanical press and hammer forging machine. The hydraulic press is suitable for forging large and complex shapes, the mechanical press is suitable for small and medium-sized products, and the hammer forging machine is suitable for high-precision and small-batch production.

4.Heat treatment

4.1 Annealing
Annealing is the process of heating the forged stainless steel plate to a certain temperature and slowly cooling after holding it for a period of time. The purpose of annealing is to eliminate the internal stress generated in the forging process and improve the plasticity and toughness of the material. The annealing temperature and time should be adjusted according to the type and composition of stainless steel.
4.2 Quenching and tempering
Quenching is the process of heating the stainless steel plate above the critical temperature and cooling it quickly to obtain high hardness and strength. Tempering is the heating of the stainless steel plate to a lower temperature after quenching, and then cooling after holding for a period of time to adjust the hardness and toughness. The quenching and tempering process should be designed according to the performance requirements of the final product.
4.3 Heat treatment equipment
Commonly used heat treatment equipment includes box furnace, well furnace and continuous furnace. Box furnaces are suitable for small batch production, well furnaces are suitable for large products, and continuous furnaces are suitable for large-scale production.

5. Surface treatment

5.1 Pickling
Pickling is the process of chemically removing oxide and impurities from the surface of stainless steel plates. Common pickling solutions include nitric acid, hydrofluoric acid and sulfuric acid. After pickling, adequate water washing and neutralization should be carried out to prevent the corrosion of the residual acid on the stainless steel plate.
5.2 Polishing
Polishing is the process of improving the surface finish of stainless steel plates. Common polishing methods include mechanical polishing, chemical polishing and electrolytic polishing. Mechanical polishing is suitable for large area and rough polishing, chemical polishing and electrolytic polishing are suitable for high precision and mirror polishing.
5.3 Coating
Coating is the coating of a protective film on the surface of the stainless steel plate to improve its corrosion resistance and aesthetics. Commonly used coating materials include paint, powder coatings and electroplating. The coating process should be selected according to the application requirements of the final product.

6. Quality inspection

6.1 Dimensional Check
The dimensional inspection is an important step to ensure that the size and shape of the stainless steel plate meet the design requirements. Common testing tools include calipers, micrometers and coordinate measuring instruments. Dimensional checks should be carried out at all stages of forging, heat treatment and surface treatment.
6.2 Non-Destructive Testing
Non-destructive testing is the process of detecting internal defects in stainless steel plates by non-destructive methods. Common nondestructive testing methods include ultrasonic testing, X-ray testing and magnetic particle testing. Non-destructive testing should be carried out after forging and heat treatment to ensure the internal quality of the product.
6.3 Mechanical properties test
Mechanical properties testing is an important step to evaluate the mechanical properties of stainless steel plates. Commonly used test items include tensile test, hardness test and impact test. The mechanical properties test should be designed according to the application requirements of the final product.

7. Cutting and forming

7.1 Cutting
Cutting is the process of cutting stainless steel plates to the required size according to demand. Common cutting methods include shearing, laser cutting and plasma cutting. Shear is suitable for straight line cutting, laser cutting and plasma cutting are suitable for complex shapes and high-precision cutting.
7.2 Forming
Molding is the process of processing stainless steel plates into final products by bending, stamping and other processes. Commonly used forming equipment includes bending machines, punching machines and hydraulic forming machines. The molding process should be designed according to the shape and size of the final product.

8. Summary

The forging process of stainless steel plate is a complex and fine process, involving material selection, heating, forging, heat treatment, surface treatment, quality testing and subsequent processing. Each step requires strict control of process parameters to ensure that the final product has excellent mechanical properties and surface quality. Through scientific process design and strict quality control, high-quality stainless steel plates can be produced to meet the needs of various applications.