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Published by VMT at Oct 19 2026 | Reading Time：About 8 minutes
Stainless steel, as an indispensable material in modern industry, is widely acclaimed for its excellent corrosion resistance and versatile application performance,such as high strength , ease of cleaning, good machinability, compliance with food or medical standards, high hardness, and wear resistance in specific grades. In the field of CNC machining parts manufacturing, the use of stainless steel is particularly common across medical, food processing, and industrial machinery sectors. This article will comprehensively introduce the basic knowledge, characteristics, advantages and disadvantages, application scenarios, as well as precautions in the use and processing of stainless steel materials, helping readers to gain a deeper understanding of stainless steel machining materials.
At the end of this article, we’ ll also share a case study detailing how we manufactured outstanding, scratch-free 304 stainless steel slider brackets for automation equipment, helping a client overcome minor surface scratches from their previous supplier while achieving a 98% pass rate and saving 15% in production costs.
Stainless steel, as the name implies, is a type of steel that is not easily rusted. Its main characteristic is the high content of chromium (usually at least 10.5%), which gives stainless steel good corrosion resistance in weak corrosive media such as air, water, and steam. Stainless steel is classified into austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel, and PH stainless steel etc., based on its metallographic structure. These different types of stainless steel are suitable for different application scenarios due to their unique chemical compositions and physical properties.
Precipitation-Hardening (PH) Stainless Steel:
Advantages:
Disadvantages:
The primary reasons for using stainless steel are its excellent corrosion resistance and versatile application performance. Stainless steel can resist corrosion from various chemicals, making it widely used in industries such as chemical, marine, aerospace, energy, pharmaceuticals, and food. Additionally, the high strength, good aesthetic appeal, and good machinability of stainless steel make it an ideal material for manufacturing various parts and equipment.
Stainless steel comes in various grades, with the most common ones including 304 stainless steel, 316 stainless steel, 430 stainless steel, etc. These different grades of stainless steel are suitable for different application scenarios due to their unique chemical compositions and physical properties. For example, 304 stainless steel has good corrosion resistance and machinability, suitable for manufacturing kitchenware, chemical equipment, medical devices, etc.; whereas 316 stainless steel has better corrosion resistance, suitable for marine environments and chemical equipment in highly corrosive environments.
The table below selects the most common stainless steel grades and provides a comparative breakdown of their properties for your reference ：
| Property | 304 (Austenitic) |
316 (Austenitic) |
430 (Ferritic) |
409 (Ferritic) |
440C (Martensitic) |
420 (Martensitic) |
2205 (Duplex) |
17-4PH (Precipitation-Hardening) |
| Tensile Strength | 515 MPa | 515 MPa | 450 MPa | 380 MPa | 750 MPa | 650 MPa | 620–880 MPa | 930–1310 MPa |
| Yield Strength | 205 MPa | 290 MPa | 250 MPa | 200 MPa | 450 MPa | 400 MPa | 450 MPa | 790–1170 MPa |
| Rockwell Hardness | 70–92 HRB | 79–95 HRB | 80 HRB Max | 80 HRB Max | 58–60 HRC | 50–55 HRC | 25–32 HRC | 32–45 HRC |
| Melting Point | 1400–1450 °C | 1375–1400 °C | 1427–1510 °C | 1480–1530 °C | 1480 °C | 1450–1510 °C | 1350–1450 °C | 1400–1440 °C |
| Thermal Conductivity | 16.2 W/m·K | 16.3 W/m·K | 26.1 W/m·K | 25.0 W/m·K | 24.2 W/m·K | 24.9 W/m·K | 19.0 W/m·K | 17.9 W/m·K |
| Magnetic Property | Non-magnetic (Magnetic when cold-worked) | Non-magnetic (Slightly magnetic when cold-worked) | Magnetic | Magnetic | Magnetic | Magnetic | Magnetic (Mixed austenite-ferrite) | Magnetic (After heat treatment) |
| Heat Resistance | ★★★☆☆ | ★★★☆☆ | ★★☆☆☆ | ★★★☆☆ | ★★☆☆☆ | ★★☆☆☆ | ★★★★☆ | ★★★★☆ |
| Corrosion Resistance | ★★★★☆ | ★★★★★ | ★★☆☆☆ | ★★☆☆☆ | ★★☆☆☆ | ★★☆☆☆ | ★★★★★ | ★★★★☆ |
| Machinability | ★★★☆☆ | ★★★☆☆ | ★★★★☆ | ★★★★☆ | ★★☆☆☆ | ★★★☆☆ | ★★★☆☆ | ★★★☆☆ |
| Weldability | ★★★★★ | ★★★★★ | ★★★☆☆ | ★★★☆☆ | ★☆☆☆☆ | ★★☆☆☆ | ★★★★☆ | ★★★☆☆ |
| Material Cost | ★★★☆☆ | ★★★★☆ | ★★☆☆☆ | ★☆☆☆☆ | ★★★★☆ | ★★★☆☆ | ★★★★★ | ★★★★★ |
For applications requiring high temperature resistance, 310 stainless steel and 316 stainless steel are good choices. Among them, 310 stainless steel has good high-temperature oxidation resistance and can be used in the manufacturing of high-temperature machinery and heat exchangers; while 316 stainless steel can maintain good corrosion resistance in high-temperature oxidizing environments and is suitable for high-temperature production equipment, petrochemicals, etc.
Stainless steel has a wide range of applications, including but not limited to:
TIG and MIG welding are common methods for some types of stainless steel. TIG welding is typically utilized for thin-walled stainless steel components, high-precision mating parts, and applications requiring clean cosmetic appearance. Conversely, MIG welding process is used by factories for medium-to-thick plates, long seams, mass production runs, or structural stainless steel products where joint strength takes precedence over fine surface appearance.
But whether a stainless steel grade welds reliably depends on its metallurgical structure and compositional factors. Refer to the table below for a detailed comparison across stainless steel types:
| Stainless Steel Type | Weldability | Representative Grades | Examples of Welded Parts / Products | Final Weld Seam Effect | Welding Method | Cost Impact | Lead Time Impact |
| Austenitic | Easy | 304, 304L, 316, 316L | Medical housings, fluid manifolds, slider brackets | Smooth seam, minimal spatter, excellent joint integrity | TIG / MIG | Low | Low |
| Ferritic | Limited | 430, 409 | Exhaust flanges, heater tubes, appliance panels | Acceptable seam strength, risk of HAZ grain coarsening (embrittlement risk) | TIG | Low to Moderate | Low |
| Martensitic | Poor (Not Recommended) | 410, 420, 440C | Not Recommended / Rarely Welded | High risk of cold cracking, severe embrittlement and hardness loss | Not Recommended (TIG with PWHT if mandatory) | High | High |
| Duplex | Moderate | 2205, 2507 | Marine pump impellers, chemical pipe connectors | High strength seam, requires precise heat input control | TIG / MIG | Moderate | Moderate |
| Precipitation-Hardening (PH) | Moderate | 17-4PH (SUS630), 15-5PH | Aerospace pins, high-load drive shafts | Requires full post-weld solution annealing and aging treatment | TIG | High | High |
The question of "which stainless steel material grade is the best" does not have a fixed answer. Different stainless steel grades have different chemical compositions and physical properties, suitable for different application scenarios. When selecting stainless steel materials, it is necessary to evaluate their performance based on specific usage environments and requirements, and choose the most suitable material accordingly.
Both 304 and 316 stainless steel are common stainless steel grades, each with its own advantages and disadvantages. 304 stainless steel has good corrosion resistance and machinability, suitable for general application scenarios; whereas 316 stainless steel has better corrosion resistance, suitable for highly corrosive environments. Therefore, when selecting stainless steel materials, it is necessary to evaluate their performance based on specific usage environments and requirements, and choose the most suitable material accordingly.
Although stainless steel has excellent corrosion resistance, it may still corrode under certain specific environments. The most common types of corrosion include pitting corrosion, intergranular corrosion, stress corrosion cracking, etc. These types of corrosion are usually related to factors such as the chemical composition of stainless steel, the usage environment, and the processing methods.
Pitting corrosion typically occurs when grades like 304 are used in marine or chloride-rich chemical processing environments, where localized microscopic pinholes form on the surface, causing unexpected fluid leakage despite a mostly intact outer appearance. To prevent this, professional manufacturing factory usually apply chemical passivation or electropolishing to remove microscopic surface inclusions and dissolve free iron and then improve the stainless steel’ corrosion resistance, or recommend upgrading to grade 316 which contains molybdenum for enhanced chloride resistance.
Intergranular corrosion arises when austenitic grades such as 304 or 316 are improperly heated during welding or high-temperature service within the 425°C to 860°C range, causing chromium carbides to precipitate at grain boundaries. You can specify low-carbon variants like 304L or 316L to restrict carbon content below 0.03%, or ask for the post-weld solution annealing services to re-dissolve carbides and restore structural integrity.
Stress corrosion cracking affects austenitic stainless steels subjected to constant tensile stress while exposed to hot chloride solutions above 60°C, resulting in sudden brittle cracking without warning. To counter this failure mode, the stress relief annealing is recommended or advise switching to duplex stainless steel grades such as 2205.
Although stainless steel is named for its resistance to rust, it is still possible to rust under certain conditions. This is mainly because the corrosion resistance of stainless steel is not absolute, but is affected by various factors such as its chemical composition, usage environment, and conditions. For example, in environments containing a large amount of chloride ions, such as seawater or swimming pool water, the corrosion resistance of stainless steel may be severely affected, leading to rust. Additionally, stainless steel is prone to rusting at damaged areas (such as scratches, impacts, etc.).
To maintain the aesthetic appeal and corrosion resistance of stainless steel, regular cleaning is necessary. When cleaning stainless steel, mild detergents and soft cloths or sponges should be used for wiping, avoiding the use of detergents containing chlorine or abrasives to prevent damage to the stainless steel surface. For stubborn stains or rust spots, specialized stainless steel cleaners or white vinegar can be used for cleaning. After cleaning, rinse with clean water and dry with a dry cloth to avoid water spots.
Stainless steel is not 100% rust-proof. In fact, the corrosion resistance of stainless steel is achieved through its unique chemical composition and microstructure, rather than being absolutely "stainless." The corrosion resistance of stainless-steel may vary under different usage environments and conditions. Therefore, when using stainless steel, it is necessary to understand its performance characteristics and limitations, and take appropriate protective measures to extend its service life.
Stainless steel has relatively high durability, primarily due to its excellent corrosion resistance and strength. Under normal usage and maintenance conditions, stainless steel products can maintain a long service life. However, it is important to note that the durability of stainless steel is not absolute, and its performance may be affected by various factors such as usage environment, conditions, and the quality of the material itself. Therefore, when selecting and using stainless steel, it is necessary to consider its performance characteristics and usage requirements comprehensively.
The most important element in stainless steel is chromium (Cr). Chromium is the basic element that imparts corrosion resistance to stainless steel. When the chromium content reaches around 12%, chromium reacts with oxygen in the corrosive medium to form a thin oxide film (passivation film) on the steel surface, which can prevent further corrosion of the steel substrate. In addition to chromium, elements such as nickel (Ni) and molybdenum (Mo) also have a significant impact on the performance of stainless steel. For example, nickel can enhance the corrosion resistance and toughness of stainless steel, while molybdenum can improve its resistance to pitting and crevice corrosion.
Comparied to other common metal materials, stainless steel provides an optimal balance of superior corrosion resistance, high hygiene compliance, and low long-term maintenance costs, making it the most dependable choice for components exposed to demanding or moisture-rich environments.
The table below compares stainless steel with five other primary engineering metals across key engineering considerations, and you will see the direct differences:
| Performance | Stainless Steel | Carbon Steel | Aluminum | Titanium | Brass | Tool Steel |
| Corrosion Resistance | Excellent to Superior | Low (Requires plating/coating) | Good (Forms protective oxide layer) | Exceptional | Good | Low to Moderate |
| Strength and Durability | High strength & toughness | High strength | Moderate strength, high specific strength | Very high strength-to-weight | Moderate strength | Extremely high hardness & toughness |
| Hygiene Compliance | Superior (Non-porous, easy to sterilize) | Poor | Fair | Excellent (Biocompatible) | Fair (Antimicrobial properties) | Poor |
| Aesthetic Appeal | High (Bright metallic finish) | Low (Dark matte, prone to rust) | Moderate to High (Ideal for anodizing) | High (Matte grey / customizable oxide) | High (Warm golden metallic finish) | Low (Functional industrial finish) |
| Recyclability | 100% Recyclable | 100% Recyclable | 100% Recyclable | 100% Recyclable | 100% Recyclable | 100% Recyclable |
| Lifecycle Cost | Low (Low maintenance & long lifespan) | Moderate (High maintenance/plating) | Low to Moderate | High (High initial investment) | Moderate | Moderate to High |
| Machinability | Moderate (Tendency to work-harden) | Excellent | Excellent (Easy high-speed milling) | Low (Challenging, low heat conduction) | Superior (Free-cutting) | Moderate to Low (Hardened state is difficult) |
| Welding Complexity | Moderate | Easy | Moderate to High (Requires skilled process) | High (Requires inert gas shield) | Low to Moderate | High (Requires pre/post heat treatment) |
| Thermal Expansion | Moderate | Moderate | High | Low | High | Low to Moderate |
| CNC Production Cost (Relative) | Moderate to High | Cost-Effective | Economical | High | Moderate | High |
| Product Examples | Precision medical tools, slider brackets, food machinery | Machine frames, heavy gears, automotive shafts | Aerospace structural parts, electronic housings | Surgical implants, aerospace pins, defense parts | Plumbing fittings, electrical connectors, bushings | Stamping dies, cutting tools, injection molds |
The main reasons for scratching of stainless steel are as follows: improper use, such as scratching the stainless steel surface with sharp objects; mechanical damage during processing, such as scratches produced during cutting, grinding, etc.; improper cleaning, such as scratching caused by using abrasive cleaners or cleaning tools on the stainless steel surface. To reduce scratching of stainless steel, it is necessary to use and maintain stainless steel products correctly and take appropriate protective measures.
Machining 304 Stainless Steel Slider Brackets for Automation Equipment and Achieving Scratch-Free Finish, 98% Yield Rate, and 15% Production Cost Savings
A leading industrial automation equipment manufacturer approached us to produce critical 304 stainless steel slider brackets (featuring complex multi-faceted milling pockets, precise bearing bores, and critical mating faces ).
Due to the material characteristics of 304 stainless steel, which features high toughness, thermal sensitivity, and a propensity to work-harden when machining, combined with the complex geometry of the bracket, achieving a smooth Ra 0.6 surface finish and a completely scratch-free surface presents manufacturing difficulties to some extent. The client was unsatisfied with their previous supplier's sample batches, where approximately 20% of the components exhibited minor surface scratches, leading to high production costs caused by lower yields.
To overcome these potential scratch issues and cost issues, our engineering team strictly controls the production:
Maintaining surface integrity through post-machining stages was equally crucial:
Through optimized cutting parameters, strict quality control, and protective packaging, we successfully produced 304 stainless steel slider brackets with an unblemished Ra 0.6 surface finish and zero surface scratches, and then boosted the overall pass rate to 98%, and helped the client reduce total production costs by 15%. The client was satisfied with both the product quality and cost optimization.
It is necessary for you to gain a deep understanding of the characteristics of the five main stainless steel types (austenitic, ferritic, martensitic, duplex, and precipitation-hardening) and their popular grades, and to precisely match them based on load conditions, corrosive media, operating temperatures, and cost budgets to prevent component failures caused by improper material selection. In addition, we also share detailed insights and solutions for common stainless steel part manufacturing issues, such as high toughness, tendency to work-harden, susceptibility to scratching, rust and corrosion prevention, burr removal, and ensuring batch-to-batch surface finish and dimensional consistency, which you can also use to evaluate what kind of factory truly makes a high-quality partner.
Facing questions or challenges regarding material selection, surface quality, or cost optimization for your stainless steel part project? Contact our precision machining experts today to help you optimize material performance, reduce production risks, and deliver perfect stainless steel components on schedule! [We support 2D Drawings (PDF files), 3D Drawings (IGS/STP/STEP files)].
Send your 2D drawings, 3D CAD models, stainless steel grade, tolerance requirements, surface finish requirements, welding or post-processing needs, prototype quantity and production quantity. VMT will review material selection, DFM, CNC machining, surface finishing, inspection and quotation requirements.
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Email: inquiry@vimetal.com.cn
What are the advantages of stainless steel CNC machining parts?
Stainless steel CNC machining parts have advantages such as strong corrosion resistance, high strength, good aesthetic appeal, etc., suitable for various application scenarios. Through CNC machining technology, high-precision and efficient processing can be achieved, meeting customers' personalized requirements.
How to customize stainless steel CNC machining parts?
To customize stainless steel CNC machining parts, it is necessary to collaborate with CNC machining factories, providing detailed part drawings and processing requirements. The CNC machining factory will perform precise machining and manufacturing based on the drawings and requirements to meet customer needs.
What role does CNC prototype machining play in stainless steel processing?
CNC prototype machining is a high-precision and efficient machining method that can quickly produce prototypes or samples of stainless steel materials. This is crucial during the product design and development stage, as it helps customers quickly verify the feasibility and performance of the product.
How to choose a suitable CNC machining service provider?
Choosing a suitable CNC machining service provider requires considering their machining capabilities, equipment level, technical strength, service quality, etc. Customers can evaluate their comprehensive strength and credibility by checking the supplier's qualifications, on-site visits, consulting other customers, etc.
How do you handle burrs on stainless steel threads and ports to protect sealing, flow, and assembly?
We combine precision tool paths during CNC machining with specialized post-processing techniques to eliminate burrs across all threads, cross-drilled ports, and internal channels. Thread deburring is performed using dedicated chamfering cycles and micro-deburring tools on the machine. For complex internal intersections and fluid ports, we utilize ultrasonic cleaning, thermal or chemical deburring, and manual micro-polishing. Every internal passage is inspected with borescope cameras to ensure that critical edge requirements are met and that zero residual burrs affect seal integrity, fluid flow, cleanliness, or final assembly.
How do you ensure surface finish consistency and batch-to-batch uniformity for stainless steel components?
Batch-to-batch consistency is maintained through a strictly controlled end-to-end manufacturing workflow. We enforce standardized tool-wear monitoring and raw material lot tracking during machining. Subsequent steps including automated washing, passivation/electropolishing, custom surface coating, and protective packaging are strictly managed. Every production batch undergoes multi-point Quality Assurance (QA) inspections using surface roughness testers (Ra measurement), coordinate measuring machines (CMM), and visual inspections under controlled lighting before final vacuum or anti-static packaging.
The above is a comprehensive introduction to stainless steel machining materials, hoping to be helpful to readers. If you have more questions or need further understanding, please feel free to consult relevant professionals.
The technical information and manufacturing advice shared on the VMT website are for general guidance only. While we strive for accuracy, VMT does not guarantee that the processes, tolerances, or material properties mentioned are applicable to every specific project. Any reliance you place on such information is strictly at your own risk. It is the buyer's responsibility to provide definitive engineering specifications for any production orders. Final specifications and service terms shall be subject to the formal contract or quotation confirmed by both parties.
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