Stainless steel is classified as such when it contains a minimum of 10.5% chromium, providing it with robust corrosion resistance attributed to the formation of a protective iron chromium oxide layer. These steels fall into five main categories: austenitic, duplex, ferritic, martensitic, and precipitation hardened. The first four categories are defined by their microstructures, while precipitation-hardened steels gain strength through heat treatment, exhibiting the highest strength among stainless steels with corrosion resistance superior to or equal to martensitic variants.
Duplex steels, though capable of achieving unparalleled strength through cold working, exhibit lower elongation. Generally, austenitics are the most expensive, ferritics are the most economical, and martensitics fall in between.
Strengths
Stainless steels boast excellent corrosion and oxidation resistance, offering a diverse range of mechanical properties. They exhibit high creep and rupture strengths, maintain an attractive appearance with minimal upkeep, and do not become brittle at low temperatures.
Limitations
While stainless steels offer exceptional properties, they come at a higher cost. Low thermal conductivity can lead to challenges such as distortion and residual stress during thermal treatments. Additionally, certain grades are prone to local corrosion and brittleness under specific conditions.
Designation
Austenitic alloys are found in the 200 and 300 series, with the former containing Cr, Ni, Mn, and N, and the latter featuring Cr, Mn, and Ni. The 400 series encompasses ferritic and martensitic steels, characterized by the presence of Cr and possibly C. The 500 series is martensitic, with low levels of Cr (<12%) and potentially some C.
Typical Uses
Stainless steel finds application in various industries, including railway cars, trucks, trailers, food-processing equipment, sinks, stoves, cooking utensils, cutlery, flatware, scissors, architectural metalwork, jet-engine parts, chemical-processing equipment, surgical tools, furnace and boiler components, seawater applications, high-temperature environments, processing of corrosive liquids, and structural applications in corrosive environments, such as pulp and paper manufacturing.
Compositional summary
Fe/<0.25C/10.5-30Cr/<15Ni/<10Mn/<5Mo with varying additions of Si, P, S
Material family
Metal (ferrous)
Base material
Fe (Iron)
Impact of Composition
Steel with low carbon content and 4-6% chromium enhancements exhibit enhanced resistance to corrosion, attributed to the development of an iron chromium oxide layer on the surface. When the chromium concentration surpasses 12%, the protective oxide has the ability to self-heal when damaged, classifying these as genuine stainless steels. Elevated temperatures may lead to a local dip in chromium levels as chromium carbides form; this issue can be mitigated by maintaining low carbon content or binding carbon with stabilizing elements like Ti or Nb. As the chromium content increases, formability decreases. Furthermore, the addition of S and Se enhances machinability.
Processing properties
Feedstocks & production:
Raw materials, including recycled stainless steel, recycled low-carbon steel, and chromium in the form of ferrochromium (a hard, brittle compound composed of approximately 80% Cr and 20% Fe), undergo melting in an electric furnace. Subsequently, the argon-oxygen decarburization process is employed to remove carbon (C) and nitrogen (N) without significant chromium loss to the slag. Additional alloying elements can be introduced through inoculation. The molten steel is then transformed into blooms, billets, and slabs, and it can also be shaped through metal powder formation or the vaporization process.
Available Forms
Stainless steel is accessible in various forms, including sheet, strip, bar, plate, and foil.
Forming
Stainless steel can undergo various forming processes, including hot-rolling, extrusion, deep drawing, and forging. While they generally exhibit favorable characteristics for cold-forming, formability diminishes with an increase in chromium content. Notably, low-carbon grades offer superior formability compared to other variants.
Machining
Machining is feasible, but due to the material’s toughness, it requires more time and is costlier than working with alloy and carbon steels. Effective cooling is essential during grinding owing to the low thermal conductivity.
Heat Treatment
Common heat treatment methods for all grades include annealing and stress-relieving. Precipitation grades undergo solution treatment and aging.
Joining
Various joining methods are applicable, such as welding, soldering, brazing, adhesive bonding, and fastening.
Surface Treatment
Stainless steel offers versatility in surface treatments, including electroplating, painting, powder-coating, mill finishes, pickling (only in the fully annealed condition), various descaling methods, mass finishing, grinding, polishing, buffing, passivation treatments, surface-blackening, coloring, terne coatings, thermal spraying, and surface modification techniques like ion implantation, laser-alloying, and laser melt/particle injection.
Notes
Embrittlement Risk:
Prolonged exposure to elevated temperatures can lead to embrittlement in stainless steels. This phenomenon is attributed to the formation of the brittle ‘sigma phase’ at high temperatures, which coats grain boundaries. Regular checks are recommended for stainless steels utilized in high-temperature applications to monitor and mitigate potential embrittlement issues over time.
Modulus Metal is a leading provider of CNC machining services for Polyamide (Nylon) in Turkey. Our team of skilled professionals utilizes state-of-the-art CNC machines to produce high-quality Nylon parts with precision and accuracy. We offer Nylon CNC machining services for a wide range of applications, and we are committed to delivering the best results to our clients.
Types of Polyamide (Nylon):
Polyamide is a group of polymers that contains amide groups (-CO-NH-) in their molecular structure. There are various types of Nylon, each with its own unique properties and characteristics. Some of the most common types of Nylon we work with include:
Nylon 6: This type of Nylon is a semi-crystalline material that offers high strength, stiffness, and toughness. It is suitable for applications that require high mechanical strength and resistance to wear and abrasion.
Nylon 6/6: This type of Nylon is a crystalline material that offers excellent mechanical properties and chemical resistance. It is suitable for applications that require high strength, stiffness, and dimensional stability.
Nylon 11: This type of Nylon is a semi-crystalline material that offers excellent impact resistance and flexibility. It is suitable for applications that require resistance to chemicals, abrasion, and impact.
Colors:
Nylon is available in a variety of colors, including natural (white), black, blue, green, red, and yellow. The color of the Nylon does not affect its mechanical properties, but it can provide aesthetic appeal or help with product identification.
Physical and mechanical properties:
Nylon (Polyamide) has excellent physical and mechanical properties, including high strength, stiffness, toughness, and chemical resistance. Some of its key properties are:
Melting temperature: The melting temperature of Nylon ranges from 220°C to 265°C, depending on the type of Nylon.
Hardness: Nylon has a hardness of around 70 to 80 on the Rockwell scale, making it relatively hard and durable.
Tensile strength: The tensile strength of Nylon ranges from 50 to 150 MPa, depending on the type of Nylon.
Flexural modulus: Nylon has a flexural modulus of around 1,000 to 3,000 MPa, making it relatively stiff and strong.
Coefficient of friction: Nylon has a low coefficient of friction, making it suitable for applications that require low friction and wear resistance.
Water absorption: Nylon has a high water absorption rate, making it suitable for applications that require good dimensional stability and resistance to moisture.
Types of machining:
At Modulus Metal, we use various types of machining techniques to produce high-quality Nylon parts, including:
Turning: Turning is a process in which a cutting tool removes material from the surface of a rotating Nylon workpiece to produce a cylindrical shape. Turning is ideal for producing parts with round shapes, such as shafts, rods, and bushings.
Milling: Milling is a process in which a rotating cutting tool removes material from a Nylon workpiece to produce a flat or contoured surface. Milling is ideal for producing complex shapes, such as gears, brackets, and housings.
Drilling: Drilling is a process in which a rotating cutting tool removes material from a Nylon workpiece to produce a round hole. Drilling is ideal for producing holes with accurate diameters and depths.
Threading: Threading is a process in which a cutting tool removes material from a Nylon workpiece to produce a screw thread. Threading is ideal for producing parts that require screw connections, such as bolts, nuts, and threaded rods.
Examples of products:
We provide CNC machining services for a wide range of Nylon parts, including:
Gears and bearings: Nylon’s excellent wear resistance and low friction properties make it an ideal material for producing gears and bearings used in various industries such as automotive, aerospace, and medical.
Structural components: Nylon’s high strength and stiffness properties make it suitable for producing structural components used in the construction of machines, equipment, and devices.
Electrical components: Nylon’s excellent dielectric properties and resistance to heat and chemicals make it an ideal material for producing electrical components such as insulators, connectors, and housings.
Automotive parts: Nylon’s excellent impact resistance, toughness, and wear resistance make it an ideal material for producing automotive parts such as fuel system components, engine covers, and brake parts.
Medical devices: Nylon’s biocompatibility and resistance to chemicals and sterilization make it an ideal material for producing medical devices such as surgical instruments, implantable devices, and prosthetics.
At Modulus Metal, we are committed to providing high-quality Nylon CNC machining services to meet the unique needs of our clients. Our team of experts works closely with clients to ensure that every part meets their exact specifications, and we use only the best materials and equipment to deliver exceptional results. Contact us today to learn more about our Polyamide (Nylon) CNC machining services.
