Stainless Steel
Stainless Steel Forged Parts
Stainless steels represent a very complex subject and versatile metal. The number of grades, heat treatments and fabricating methods fill many books. The 200 series stainless steel is a low-nickel austenitic stainless steel alloy that contains chromium, manganese, and nitrogen. It’s a cost-effective alternative to 300 series stainless steel, which has a higher nickel content. The 400 series stainless steel is a type of stainless steel alloy with a higher carbon content than 300 series stainless steel. It’s known for its high strength and wear resistance, and is often used in parts that need to perform well in demanding mechanical conditions. The 500 series stainless steel is a chromium alloy that’s heat resistant and used in applications where heat is a concern. It is a martensitic stainless steel, which means it is magnetic and hardenable with heat treatment. There are also duplex types (e.g.: 2205), whose chemistry is adjusted to form certain percentages of delta ferrite, and are highly resistant to stress corrosion cracking. There is a further type, precipitation-hardening (PH) grades, tailored to give specified properties from relatively low temperature aging treatments.
By far the greatest range of grades is found in the 300 series, also known as austenitic stainless steels, where the basic 304 grade, itself a good stainless workhorse, may be modified by increasing the chromium and nickel contents, or by additions of elements such as molybdenum and copper. These additions serve to increase corrosion resistance in many aggressive media.
Common stainless steels include:
304/304L, 316/316L, 321, 410, 416, 420, 422, and 431, 2205 and 2207. Common specifications include ASTM A182 F-Series, A276, A564, A705, A688, AISI, AMS, ASME, UNS, and international standards depending upon the shape of the alloy steel for its end use.
The austenitic stainless steels are noted for their strength at high temperatures, and in fact two or three times as much energy is required to forge the 300 series stainless steels as is required to forge carbon and alloy steels. Forging temperatures must be closely controlled, and cooling from these temperatures will normally result in grain boundary carbide precipitation. As such, forgings should be annealed at around 1950ºF (1065ºC) and rapidly cooled through the temperature range 1500 to 900 ºF , (815 to 480ºC.)
The 300 series stainless steels are noted for both their heat resistance, and their corrosion resistance in many media. AMFG has access to Information on these properties, and we would be pleased to help with this aspect of any inquiry.
Stainless steels, from the 400 series heat-treatable martensitic grades, through the 400 series ferritic types, and the 300 series austenitic types, represent alloys that are most commonly found in a broad range of industries and applications. The 400 ferritic series cannot be hardened by heat treatment, and have limited applications as forgings. Forging temperatures should be closely controlled to avoid grain growth.
Special precautions are taken when forging the 400 martensitic grades, to avoid the formation of delta ferrite, which in some grades reduces forgeability. By adjusting forging temperatures and cooling rates, the 400 series grades may be applied to high-strength, wear-resistant applications, or to long-time service at elevated temperatures up to 1100ºF (600ºC.) Heat treatment of the 400 series martensitic grades, where proven annealing, hardening, and tempering temperatures will render the materials suitable for further processing or for a specific end use, are taken into consideration when making forged parts or seamless rolled rings.
Duplex stainless steels are in a category of their own and involve the adjustment of chemical analysis – particularly chromium and nickel contents – to allow the formation of a significant percentage of delta ferrite, and a subsequent increased resistance to stress corrosion cracking. This is particularly important for end uses in chemical processing industries.
Precipitation-hardening (PH) stainless steels combine corrosion resistance with mechanical properties that may be adjusted by low temperature aging treatments following a solution heat treatment.
All Metals & Forge Group takes great pride in maintaining one of the most stringent ISO9001, AS9100 quality systems in the open die forging and seamless rolled ring industry. It begins with learning the customer’s end use, required forging surface condition, mechanical properties of the specified material and alloy, forged shape, heat treatment, delivery need, and competitive price, coupled with forging soundness proven by ultrasonic testing, and care in packing goods to arrive in pristine condition at the customer’s desired location. Every step is monitored by the quality system at AMFG and continuously improved.
AMFG performs rough machining to within 3mm of finish dimensions to reduce the CNC cost at the customer’s machine shop for all the forged shapes the company produces. The rough machine surface condition is 250 RMS so that proper quality testing can be performed on each part – the AMFG standard.
The company can perform finish machining to within .001 of an inch for final tolerance and 64 or 32 RMS surface finish. This level of quality and precision is unique in an industry where other company’s parts are often delivered black, as forged, or with a rough machined surface of 500 RMS without the internal or external steps and dimensions to reduce machining costs.
From inquiry to invoice, All Metals & Forge Group quality is managed and not assumed. Whether the need is for one part, an entire project, or a production run, AMFG delivers.
U.S. 1 (973) 276-5000 • 1 (800) 600-9290 • Canada 1 (416) 363-2244
Fax: 1 (973) 276-5050 • Sales@Steelforge.com
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In the U.S. 1 (973) 276-5000 / 1 (800) 600-9290.
In Canada 1 (416) 363-2244.
Email us at sales@steelforge.com.
