Stainless steel has the advantages of high corrosion resistance, hygiene, and strength, it is a commonly used material in investment casting or lost wax casting process to creat precise stainless steel components for various applications, such as food machinery, marine hardwares, architectural hardwares, medical components, etc.
While there are many options of stainless steel casting grades, how can you ensure you are selecting the appropriate cast stainless steel grade for your specific needs?
Factor 1 – Casting Process
Since we are talking about how to select a suitable stainless steel grade for casting, there is no doubt that the stainless steel grade selected is castable (refer to the castability of stainless steel). Although there are hundreds of stainless steel grades found, not all of them could be cast. The fluidity of molten steel is very critical, while some stainless steel grades have poor fluidity, but good machinability. Commonly used cast stainless steel grades are: 201, 303, 304, 309, 316, 410, 17-4 ph, 2205, 2207, etc.
In China even in the world, most stainless steel foundries could only cast stainless steel grades like 304 and 316 stainless steels. For precipitation-hardening stainless steel and duplex stainless steel, few stainless steel foundry could investment cast them. CFS Foundry has over 30 years’ experience in the field of stainless steel investment casting, we can cast all the stainless steel grades mentioned above including 17-4 ph and 2205 duplex stainless steels.
Factor 2 – Corrosion Resistance
Corrosion resistance is the main reason for choosing a stainless steel casting grade. It is necessary to understand the amount of corrosion resistance in some stainless steels. Different grades come with different amounts of corrosion resistance.
For example, austenitic stainless steels can give you the most corrosion resistance since high amounts of chromium are present. Thus, investment casting of 304 stainless steel is usually done in our stainless steel foundry when corrosion resistance is vital. 316 stainless steel, with its added molybdenum content, has better corrosion resistance than 304 stainless steel, is preferred to cast stainless steel components for marine and chemical applications.
Factor 3 – Quality (strength, ductility, and toughness, etc)
Casting quality is one of the most important factos to consider a stainless steel casting grade. The casting quality mainly lies in the strength, ductility, and toughness of stainless steel.
When it comes to austenitic stainless steel, for the presence of nickel element, it provides the highest toughness and ductility among all types of stainless steel casting grades. For cast stainless steel grades with higher chromium, molybdenum, and nickel, the corrosion resistance are always the better.
Moreover, make sure that you should not be focusing solely on the alloy content when choosing a grade of stainless steel. When there is a high requirement on the strength, precipitation-hardening stainless steel or duplex stainless steel casting is suggested. CFS Foundry ever developped a safety stirrup design for our customer in Europe, high strength is required, so we made cast stainless steel samples with several grades for their selection, after testing, they prove that 2205 duplex stainless steel shows the best strength, eventually, we moved on mass production with the ideal strength.
Note that when post machining is operated after stainless steel casting, heat treatment is better to be operated, because, it can remove the inner stress and decrease the strength slightly, which can benefit further machining operation.
Factor 4 – Magnetic Properties
Magnetic properties should also be considered when choosing a reliable stainless steel casting grade for your part.
Basic stainless steel displays a ‘ferritic’ structure and is magnetic as a result of the addition of chromium. You can harden it by adding carbon, thus making it ‘martensitic.’
On the other hand, the most common stainless steels are austenitic as they come with higher chromium content. You will also find nickel, which modifies the physical structure of the steel, making it non-magnetic.
Austenitic grades have a low magnetic reaction or ‘relative magnetic permeability.’ The stainless steel grades rich in nickel content like the 316 or 310 grades are non-magnetic in any situation.
Thus, you can use them in applications where you require a non-magnetic metal. If you are looking for stainless steel grades with high magnetic response, opt for the ferritic and martensitic stainless steel grades (400 series). They come with high permeabilities and are classified as ‘ferromagnetic.’ Also, consider the Duplex grades like 2205 while looking for ferromagnetic stainless steel grades.
CFS Foundry can also provide demagnetization process by adding nickel if the casting grade is magnetic, while you want to have a non-magnetic status.
Selecting a Stainless Steel Casting Supplier
CFS Foundry is the top leading stainless steel investment casting supplier in China. If you feel difficult to select a suitable grade for your stainless steel casting project, pls contact us for a professional consultation, or we can also provide samples in different grades for testing. Our stainless steel foundry can help you prioritize your material requirement and guide you toward choosing the perfect cast stainless steel grade for your application.