Analysis of Processing Technology for A2-70 Stainless Steel

I. Forging Process

Forging is the initial and critical step in A2-70 stainless steel processing. Under high-temperature conditions, A2-70 stainless steel billets are heated to a suitable temperature range (typically 1050–1150°C) to achieve good plasticity. External force is applied via forging hammers or presses to induce plastic deformation of the metal, which improves the internal structure, refines grain size, and enhances the material’s density and mechanical properties.

During forging, the deformation amount and deformation rate must be strictly controlled. Excessively high temperatures can lead to coarse grains, while excessively low temperatures may cause forging cracks—both of which compromise product quality. After forging, the billets can be processed into rods, plates, and other specifications based on subsequent processing needs, laying the foundation for further manufacturing.

II. Machining (Cutting Process)

Machining is a key method for shaping forged A2-70 stainless steel billets into parts of specific geometries, including turning, milling, and drilling operations. Due to A2-70 stainless steel’s high toughness and tendency for work hardening, challenges such as rapid tool wear and difficult chip breaking often arise during cutting.

To address these issues:

High-performance tool materials (e.g., cemented carbide tools or ceramic tools) are required, as their high hardness and wear resistance effectively handle the material’s machining characteristics.
Rational selection of cutting parameters is crucial: a low cutting speed (generally controlled at 50–80 m/min) and a large feed rate (0.1–0.3 mm/r) help reduce work hardening, improving machining efficiency and surface quality.
Appropriate cutting fluids are indispensable: they cool and lubricate the tool, reduce cutting force, and prevent chip adhesion to the tool—ensuring machining accuracy and surface finish.

III. Forming Process

Two primary methods are used for A2-70 stainless steel forming: cold forming and hot forming.

Cold Forming

This includes stamping, bending, and drawing processes. Leveraging A2-70 stainless steel’s good plasticity and toughness, the material is shaped into the desired form at room temperature using molds. Cold forming is suitable for manufacturing complex-shaped parts with high precision requirements, such as electronic device housings and small mechanical components.

However, cold forming causes work hardening, which increases material hardness and strength while reducing plasticity and toughness. Therefore, intermittent annealing is required during processing to eliminate work hardening and restore the material’s plasticity for subsequent operations.

Hot Forming

Hot forming involves shaping the material after heating it to a specific temperature. Compared to cold forming, it requires less forming force (reducing equipment load) but demands extremely precise temperature control. The heating temperature and holding time must be accurately regulated to ensure the formed parts meet performance requirements.

IV. Welding Process

Welding is essential for joining A2-70 stainless steel components. Due to the material’s poor thermal conductivity and high coefficient of linear expansion, welding is prone to issues such as hot cracks and deformation. To ensure welding quality:

Suitable welding methods (e.g., argon arc welding, gas metal arc welding) are selected—these methods offer stable arcs and effective protection, minimizing welding defects.
Welding materials with compositions similar to the base metal are used to ensure the weld zone matches the base metal in corrosion resistance and mechanical properties.
Pre-welding preparation: Welded areas are thoroughly cleaned to remove oil, rust, and other impurities, preventing pores, slag inclusions, and other defects during welding.
Welding parameter control: Low current and high welding speed are adopted to reduce heat input, lowering the risk of welding deformation and hot cracks.

V. Surface Treatment

Surface treatment is critical for enhancing the performance and appearance of A2-70 stainless steel products. Common processes include passivation, electrolytic polishing, and coating:

Passivation: A denser, more stable passive film is formed on the A2-70 stainless steel surface via chemical methods, further improving corrosion resistance. This process is simple and cost-effective, making it one of the most widely used surface treatments.
Electrolytic polishing: Significantly improves surface finish, enhances aesthetics, and reduces surface roughness (minimizing dirt adhesion). It is particularly suitable for products with high appearance requirements, such as decorative components and medical devices.
Coating: A specialized coating (e.g., anti-corrosion coating, wear-resistant coating) is applied to the surface. For example, in marine engineering, anti-corrosion coatings are used to enhance the salt spray corrosion resistance of A2-70 stainless steel fasteners.

The processing of A2-70 stainless steel encompasses forging, machining, forming, welding, and surface treatment—all interconnected and mutually influential. Only by strictly controlling the parameters and operational key points of each process can the performance advantages of A2-70 stainless steel be fully utilized, producing high-quality, high-performance products that meet the application needs of diverse industrial fields.

Supplementary Notes on Key Terms

Work hardening: A phenomenon where metal hardness and strength increase, while plasticity decreases, due to plastic deformation during cold processing (e.g., cold forming, cutting). Annealing (heating to a specific temperature and cooling slowly) is required to restore the material’s ductility.
Passive film: A thin, inert oxide film (primarily chromium oxide) naturally formed on the surface of stainless steel. Passivation treatment enhances this film’s density and stability, further improving corrosion resistance.
Argon arc welding: A welding method that uses argon gas to protect the weld zone from atmospheric contamination. It is widely used for stainless steel welding due to its ability to produce high-quality, low-defect welds.
Cemented carbide tools: Tools made by sintering hard carbide particles (e.g., tungsten carbide) with a metal binder. They offer high hardness and wear resistance, making them ideal for machining tough materials like A2-70 stainless steel.

Analysis of Processing Technology for A2-70 Stainless Steel