Many customers write 304, 316, 304L, and 316L on drawings or quotations, but in the stainless steel casting production stage, you often see different grades.CF8、CF8M、CF3、CF3MThese casting grades. For purchasing, engineering, and foreign trade sales personnel, if they are not clear about the correspondence between the two sets of grades, it is easy to cause misunderstandings in quotations, material confirmation, and quality documents.
In short, CF8 is commonly used for 304 stainless steel castings, CF8M for 316 stainless steel castings, and CF3 and CF3M for 304L and 316L low-carbon castings, respectively. However, this is not a complete equivalence. Casting grades have their own standards and composition ranges, and the final determination should be based on drawings, applicable standards, chemical composition, heat treatment, and testing requirements.
What are CF8, CF8M, CF3, and CF3M?
CF8, CF8M, CF3, and CF3M are common austenitic compounds.Stainless steel casting gradesCommonly usedPrecision castingProcesses such as silica sol casting, water glass casting, and sand casting are widely used in pumps and valves, food machinery, building hardware, pipe fittings, marine hardware, chemical equipment parts, and various non-standard mechanical parts.
These grades typically appear in cast stainless steel standards such as ASTM A351, ASTM A743, and ASTM A744. Compared to the commonly used terms 304, 316, 304L, and 316L for plates, bars, and forgings, the CF series leans more towards the casting system. While 304/316 can be used for clarification in engineering communication, it is recommended to explicitly specify the casting grade and its corresponding standard when providing formal quotations and for production.
For pressure-bearing components, export components, food processing equipment, and chemical equipment, it is not recommended to produce them directly by simply writing "304 stainless steel" or "316 stainless steel". The casting grade and acceptance standards should be confirmed.
Comparison table of CF8, CF8M, CF3, CF3M with 304 and 316
| Casting grade | Common corresponding forging and rolling grades | type | Main features | Common Applications |
|---|---|---|---|---|
| CF8 | 304 | Austenitic stainless steel castings | General purpose, corrosion resistant, and low cost | General pumps and valves, food machinery, building hardware |
| CF8M | 316 | Molybdenum-containing austenitic stainless steel castings | Better resistance to chloride ion corrosion | Chemical pumps and valves, coastal environments, marine hardware |
| CF3 | 304L | Low carbon austenitic stainless steel castings | Welding provides better resistance to intergranular corrosion. | Welded structural components, thin-walled castings |
| CF3M | 316L | Low-carbon molybdenum-containing austenitic stainless steel castings | Better corrosion resistance and weldability | Food, pharmaceuticals, chemicals, marine equipment |
In everyday communication, CF8 is often understood as cast version of 304 stainless steel, CF8M as cast version of 316 stainless steel, CF3 as cast version of 304L stainless steel, and CF3M as cast version of 316L stainless steel. This correspondence is helpful for quick material selection, but it cannot replace the formal standard.
When quoting and producing, it is essential to confirm the applicable standards, composition range, heat treatment status, whether a material report is required, spectral analysis, mechanical properties, non-destructive testing, and pressure testing. This is especially important for pressure-bearing valve bodies, pump bodies, pipe fittings, and chemical equipment parts; the clearer the material confirmation, the fewer disputes will arise later.
What do the letters and numbers in these brand names mean?
While the CF series designations don't require overly academic interpretation, understanding their basic meaning helps in reading drawings and standards. "C" typically indicates a cast steel series for corrosion-resistant applications, and "F" represents an iron-based alloy. The numbers distinguish material categories and composition systems. "M" can generally be understood as containing molybdenum, which is a key reason why CF8M and CF3M exhibit better resistance to chloride ion corrosion.
Low-carbon grades such as CF3 and CF3M are generally more suitable for subsequent welding or scenarios requiring reduced risk of intergranular corrosion. Here, "low-carbon" does not refer to low strength, but rather emphasizes post-weld corrosion resistance and stability. For castings, if there are subsequent weld repairs, welded assembly, pipe welding, or long-term exposure to corrosive media, low-carbon grades are worth prioritizing.
Differences in chemical composition: Focus on carbon content and molybdenum element.
The most noteworthy differences between CF8, CF8M, CF3, and CF3M are their carbon content and molybdenum content. The "M" in CF8M and CF3M can be understood as indicating the presence of molybdenum, which enhances the material's resistance to pitting corrosion and chloride ion corrosion. In environments such as the seaside, salt spray, saltwater, and certain chemical media, molybdenum-containing materials are generally more reliable.
The low carbon content of CF3 and CF3M makes them more suitable for welded parts and components that need to maintain corrosion resistance after welding. If the product requires welding later or will be exposed to a corrosive environment for a long time, low carbon or molybdenum-containing materials should be given priority, rather than simply choosing the lowest unit price.
| Brand | Carbon content characteristics | Does it contain molybdenum? | Chloride ion corrosion resistance | Post-welding stability |
|---|---|---|---|---|
| CF8 | Standard carbon content | Molybdenum-free | generally | generally |
| CF8M | Standard carbon content | molybdenum | better | generally |
| CF3 | low carbon | Molybdenum-free | generally | better |
| CF3M | low carbon | molybdenum | better | better |
How to choose between CF8 and CF8M?
CF8 is suitable for general clean water environments, indoor or outdoor use, general food machinery parts, building hardware, general machinery accessories, and cost-sensitive projects. Its advantages include strong versatility, relatively easy control of procurement and production costs, and stable performance under normal operating conditions.
CF8M is suitable for humid coastal environments, chloride-containing environments, chemical pumps and valves, marine hardware, parts in contact with corrosive media, and projects with higher corrosion resistance requirements. Due to its molybdenum content, CF8M is generally more reliable than CF8 in salt spray, salt water, and some mildly corrosive media.
The material selection conclusion can be made according to this idea: CF8 is preferred for ordinary environments; CF8M is preferred for saline, humid, and slightly chemical environments.If the medium is complex, the temperature is high, or the risk of component failure is high, further evaluation of CF3M, 2205 duplex steel, or other corrosion-resistant materials should be conducted.
What scenarios are CF3 and CF3M suitable for?
CF3 can be regarded as a type of 304L casting, suitable for parts that need to reduce the risk of intergranular corrosion after welding, thin-walled stainless steel castings, subsequent welded assemblies, and scenarios where post-weld corrosion resistance and stability are required but the medium is not highly corrosive.
CF3M can be considered a type of 316L casting, suitable for parts used in food, pharmaceutical, and chemical equipment, as well as parts that require welding and corrosive environments, and high-performance pumps, valves, and pipe fittings. It combines low carbon content with molybdenum content, giving it advantages in weld stability and resistance to chloride ion corrosion.
It needs to be emphasized that,Low carbon does not equal low strength. The L is more for improving corrosion resistance after welding.If the customer's drawings specify 304L or 316L, the foundry should usually further confirm whether it corresponds to CF3 or CF3M, and confirm the composition in conjunction with the standard range.
Recommended grades for different application scenarios
| Application scenarios | Recommended brand | Reasons for selection |
|---|---|---|
| ordinary mechanical parts | CF8 | Low cost and highly versatile |
| Ordinary clean water pump valve | CF8 | The corrosion resistance is basically sufficient. |
| Seaside Building Hardware | CF8M | More resistant to salt spray and chloride ion corrosion |
| Chemical pumps and valves | CF8M or CF3M | Confirmation needs to be based on the medium. |
| Food machinery welding parts | CF3 or CF3M | Better stability after welding |
| Pharmaceutical equipment parts | CF3M | Higher requirements for corrosion resistance and hygiene |
| Marine hardware | CF8M or CF3M | More suitable for humid, saline environments |
The above are just general suggestions and not the final answer for all projects. For example, conditions such as long-term seawater immersion, high-temperature chlorine-containing media, strong acids and alkalis, and pressure-bearing safety components require reassessment based on the media and usage conditions, and duplex steel or higher-grade materials should be selected if necessary.
What should be considered when quoting prices and during production?
When customers inquire about prices, it is recommended to provide as much complete information as possible. Simply writing "304" or "316" is sometimes inaccurate. For casting projects, it is best to specify whether it is CF8, CF8M, CF3, or CF3M, or provide the applicable standard for the factory to confirm.
- Drawings or samples;
- Material grade or reference grade;
- Implementation standards;
- Usage environment;
- Contact medium;
- Operating temperature and pressure;
- Does welding or repair welding need to be done?
- Is CNC machining required?
- Surface treatment requirements, such as sandblasting, polishing, pickling and passivation;
- Annual usage or quantity per batch.
If the castings require pressure testing, flaw detection, mechanical property testing, material reports, or third-party inspection, these should be specified during the quotation stage. Testing requirements affect production processes, delivery times, and prices; they should not be added just before shipment.
Stainless Steel Casting Grade Selection Recommendations
在Stainless steel precision castingIn project selection, material selection should not be based solely on grade; it must also be comprehensively assessed in conjunction with product structure, usage environment, processing allowance, testing requirements, and cost control. For ordinary aquatic environments, CF8 can be used for evaluation; for chlorinated and humid environments, CF8M should be the primary consideration; and for welded structures, CF3 or CF3M should be prioritized.
From a factory's perspective, reasonable material selection also needs to consider the difficulty of casting and the cost of post-processing. Complex thin-walled parts, pump and valve parts with many sealing surfaces, small parts with many threaded holes, and exterior parts that require polishing can all have significant cost differences due to differences in materials and post-processing requirements.
Summarize
CF8 is commonly used for 304 stainless steel castings, CF8M is commonly used for 316 stainless steel castings, CF3 is commonly used for 304L low-carbon stainless steel castings, and CF3M is commonly used for 316L low-carbon molybdenum-containing stainless steel castings. CF8 is chosen for general environments, CF8M for corrosive environments, and CF3 or CF3M for high welding requirements.
For chemical, food, pharmaceutical, and coastal environments, it's not enough to simply look at the corresponding grade relationships; the medium, temperature, welding, processing, and testing requirements must also be considered. The goal of material selection is not to choose the most expensive material, but rather to select materials that match the operating conditions, are production-controllable, and have a reasonable cost.
Haijin Stainless Steel focuses on stainless steelPrecision castingWe offer silica sol casting and CNC precision machining, and can customize various stainless steel castings such as CF8, CF8M, CF3, CF3M, and 2205 duplex steel according to customer drawings or samples.
If you are unsure how to convert 304, 316, 304L, and 316L on your drawings to casting grades, please provide drawings, samples, or usage environment requirements. We can assist you with material selection and process evaluation.
FAQ
1. Does CF8 correspond to 304 stainless steel?
In engineering, CF8 is often understood as a type of 304 stainless steel casting, but strictly speaking, CF8 is a casting grade, while 304 is mostly used for forged and rolled materials. Formal production should be based on drawings, standards, and chemical composition.
2. What are the differences between CF8M and 316?
CF8M is a common grade of molybdenum-containing austenitic stainless steel castings, often corresponding to 316 in engineering. The two grades differ in their systems: CF8M is used for casting standards, while 316 is more commonly used for plates, bars, and forged/rolled products.
3. What are the differences between CF3 and CF8?
CF3 is a low-carbon austenitic stainless steel casting, often corresponding to 304L; CF8 often corresponds to 304. CF3 is more suitable for scenarios where the risk of intergranular corrosion needs to be reduced after welding.
4. What operating conditions is CF3M suitable for?
CF3M is often used in conjunction with 316L and is suitable for parts that are both weldable and corrosive in environments, such as food, pharmaceutical, and chemical equipment, high-requirement pumps and valves, and some coastal equipment.
5. The drawing specifies 304 stainless steel. Can CF8 stainless steel be used directly during casting?
Most common projects can be evaluated according to CF8, but it is not recommended to use the default settings directly. The applicable standards, composition range, usage environment, whether welding is required, and testing requirements should be confirmed. If necessary, the materials should be jointly confirmed by the customer and the foundry.
