The common materials for stainless steel shafts mainly include austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, duplex stainless steel, and precipitation hardening stainless steel. Different materials have their own emphasis on corrosion resistance, strength, hardness, and processing performance due to differences in composition and structure. The following are specific classifications and characteristic analyses:

1、 Austenitic stainless steel (300 series)
Representative grades: 304 (06Cr19Ni10), 316 (06Cr17Ni12Mo2), 321 (1Cr18Ni9Ti)
characteristic:
Excellent corrosion resistance: containing 18% -20% Cr and 8% -12% Ni, forming a dense passivation film on the surface, which can resist corrosion from atmosphere, water, acid and alkali.
Non magnetic: The austenitic structure makes it non-magnetic and suitable for magnetic sensitive applications.
Good processing performance: can be strengthened through cold processing (such as cold rolling, cold drawing), but cannot be strengthened through heat treatment.
Excellent low-temperature toughness: It maintains good toughness even at -196 ℃ and is suitable for low-temperature environments.
Application Scenario:
304 stainless steel shaft: for general applications such as food processing equipment, medical devices, chemical pipelines, etc.
316 stainless steel shaft: containing 2% -3% Mo, with stronger resistance to pitting and crevice corrosion, suitable for marine environments, pharmaceutical equipment, etc.
321 stainless steel shaft: adding Ti element, stabilizing carbides, avoiding intergranular corrosion, suitable for high-temperature welding scenarios.
limitations:
Low hardness (HRC ≤ 30), insufficient wear resistance, requiring surface treatment (such as chrome plating, nitriding) to improve wear resistance.

2、 Martensitic stainless steel (400 series)
Representative grades: 440C (9Cr18Mo), 420 (2Cr13), 431 (1Cr17Ni2)
characteristic:
High hardness: containing 0.95% -1.2% C, the hardness can reach HRC58-62 after heat treatment, and the wear resistance is excellent.
Moderate corrosion resistance: chromium content 12% -18%, resistant to atmospheric and water corrosion, but not as good as austenitic stainless steel.
Magnetism: The martensitic structure gives it magnetism, and its properties can be adjusted through heat treatment.
Poor welding performance: High carbon content can easily lead to welding cracks, requiring preheating and post heating processes.
Application Scenario:
440C stainless steel shaft: High wear resistant scenarios, such as cutting tools, bearings, pneumatic valves, precision measuring tools, etc.
420 stainless steel shaft: suitable for occasions with high hardness requirements but general corrosion resistance requirements, such as surgical instruments, molds, etc.
431 stainless steel shaft: containing Ni element, with corrosion resistance better than 420, suitable for ship shaft systems, pump shafts, etc.
limitations:
Poor welding performance, strict control of welding process is required.
Corrosion resistance is lower than that of austenitic and duplex stainless steel, and it is not suitable for strong corrosive environments.

3、 Ferritic stainless steel (400 series)
Representative grades: 430 (1Cr17), 444 (00Cr18Mo2)
characteristic:
Good corrosion resistance: containing 12% -30% Cr, resistant to atmospheric and water corrosion, but not as good as austenitic stainless steel.
Magnetism: The ferrite structure gives it magnetism.
Poor processing performance: low plasticity, easy to crack during cold processing, usually used in hot rolling or forging state.
Low cost: Does not contain Ni element, priced lower than austenitic stainless steel.
Application Scenario:
430 stainless steel shaft: suitable for cost sensitive applications with low corrosion resistance requirements, such as building decoration, automotive exhaust systems, etc.
444 stainless steel shaft: containing Mo element, with pitting corrosion resistance better than 430, suitable for hot water tanks, solar water heaters, etc.
limitations:
Low hardness and wear resistance, not suitable for high load or wear scenarios.
Poor processing performance makes it difficult to manufacture complex shaped shaft components.

4、 Dual phase stainless steel (200 series/300 series)
Representative grades: 2205 (00Cr22Ni5Mo3N), 2507 (00Cr25Ni7Mo4N)
characteristic:
Excellent corrosion resistance: containing 22% -25% Cr and 4% -7% Mo, it combines the advantages of austenitic and ferritic stainless steels, with outstanding resistance to pitting corrosion, crevice corrosion, and stress corrosion.
High strength: The yield strength is twice that of 304 stainless steel, suitable for high load scenarios.
Good welding performance: By controlling the heat input and cooling rate, welding cracks can be avoided.
High cost: containing Mo and Ni elements, the price is higher than ordinary stainless steel.
Application Scenario:
2205 stainless steel shaft: suitable for corrosive environments such as offshore platforms, chemical equipment, pulp and paper.
2507 stainless steel shaft: containing higher Mo and N elements, with better corrosion resistance, suitable for extreme environments such as seawater desalination and flue gas desulfurization.
limitations:
The processing difficulty is relatively high, requiring the use of specialized cutting tools and cutting parameters.
High cost, not suitable for cost sensitive situations.

5、 Precipitation hardened stainless steel (600 series)
Representative grades: 17-4PH (0Cr17Ni4Cu4Nb), 15-5PH (0Cr15Ni5Cu4Nb)
characteristic:
High strength: By aging treatment, intermetallic compounds (such as Ni ∝ Al, Ni ∝ Ti) are precipitated, and the strength can reach over 1300MPa.
Good corrosion resistance: containing 15% -17% Cr, resistant to atmospheric and water corrosion, but not as good as austenitic stainless steel.
Heat treatment strengthening: Adjust performance through solution treatment and aging treatment to meet different needs.
Processing performance: Good plasticity in solid solution state, suitable for cold processing, and significantly improved hardness after aging.