Stainless Steel Heat Treating
Quality Processing for Stainless Steel
At Paulo, we understand that stainless steel’s unique corrosion resistance and mechanical properties make it indispensable across various industries. Our advanced heat treatment processes enhance these inherent characteristics, ensuring that components not only withstand harsh environments but also meet stringent performance specifications. Leveraging Paulo’s proprietary datagineering approach, we offer precise, data-driven solutions that drive better part performance.
Enhancing Corrosion Resistance and Strength
Stainless steel’s elevated chromium content provides exceptional resistance to rust and oxidation, making it a top choice for applications exposed to moisture and corrosive elements. Depending on the alloy, stainless steel can also offer high strength and toughness, making it suitable for critical parts in industries like automotive, aerospace, medical, and food processing. With our expertise in metallurgy, we enhance these materials’ durability and maintain their dimensional integrity under various operational stresses.
Stainless Steel Components We Process
- Stampings
- Brackets
- Industrial blades
- Machined Parts
- Gears
- Fasteners
- Medical Instruments
Related
View AllStainless Steel Alloys We Process
Austenitic Stainless Steels (304, 316)
Austenitic stainless steels, such as 304 and 316, are high-chromium steel grades with the greatest corrosion resistance of commonly used stainless steels. Heat treatment does not increase the hardness of austenitic stainless steel, but it can enhance corrosion resistance and reduce hardness.
Cold working manufacturing processes can sometimes introduce ferromagnetism to austenitic stainless steels, which is undesirable for applications such as surgical instruments, medical devices, electronics, and some types of fasteners. Annealing is a common process for these types of parts because it can eliminate the ferromagnetism caused by cold working.
Austenitic Stainless Steel Hardness Ranges
Annealed 304 and 316 can easily drop to 80 HRB. Cold-worked product will approach the mid 40s HRC.
Ferritic Stainless Steels (430)
Ferritic stainless steels, such as 430, have less nickel content than austenitics and comparable amounts of carbon. However, the effect of heat treatment is generally the same. Ferritic stainless components can become more corrosion-resistant as a result of annealing, but thermal processing will not increase its hardness.
Compared to austenitic and martensitic stainless steel, ferritic stainless is best suited for cost-conscious applications where components don’t require high durability or extreme temperature resistance. For example, car exhausts and bathroom fixtures are commonly made from ferritic stainless steel.
Ferritic Stainless Steel Hardness Ranges
Annealed ferritic stainless steel can easily drop to 85 HRB. Cold-worked product will approach 25 HRC.
Martensitic Stainless Steels (410, 416, 420)
Martensitic stainless steels like 410, 416, 420, and 440C are generally the strongest grade of stainless steel available due to higher carbon content and less nickel than their austenitic counterparts.
Mold-grade stainless steels are a subgroup of 420. These special grades have better polishability, ideal for machined parts, plastic molding dies, and firearm components.
Martensitic Stainless Steel Hardness Ranges
AISI specification dictates that 410 and 416 have 0.15% carbon or less. For striking the perfect balance between hardness and machinability, carbon content between 0.12% and 0.15% carbon is ideal. Within this range, a hardness of around 38 HRC can be achieved. 420 steel has more carbon (up to 0.25% for mold-grade) and is commonly heat treated to a hardness range of 48-52 HRC.
Precipitation Hardening Stainless Steels (17-4, 13-8)
Stainless steels are commonly “aged,” a process also known as precipitation hardening. Precipitation hardened stainless steels such as 17-4 and 13-8Mo provide increased corrosion resistance and are ideal for service in high-heat environments. During the aging process, particles “precipitate” out of the intermetallic structure, allowing the material to harden—which is why this process is called “precipitation hardening. A key advantage of this material is that it’s highly hardenable and has corrosion resistance similar to austenitic grades.
Key Specs for Precipitation Hardening
- A286 stainless steel is commonly used to make fasteners for applications that require high corrosion and heat resistance, namely aerospace and specialty automotive. For example, cars with turbochargers will use exhaust fasteners made from A286. The achievable hardness range for A286 is 32-38 HRC.
- 15-5, 13-8Mo, and 17-4 stainless steels are used in aerospace tooling and engine parts. These materials are also used widely in tool and die applications and firearms components because they tend to be extremely dimensionally stable and amenable to tight tolerances and provide better corrosion resistance than martensitics.
- 17-7 stainless steel is primarily used in aerospace, typically requiring an austenite condition followed by age hardening in a vacuum furnace. Within 17-7, you have different conditions, each with their own achievable hardness range. CH900 can approach 50 HRC, RH950 is typically heat treated to 43-47 HRC, and TH1050 is 40-43 HRC.
Heat Treatment Processes for Stainless Steel
Annealing
Annealing is a controlled heating and cooling process that maximizes corrosion resistance and reduces hardness. It’s the first step in heat treating any stainless steel.
When cold forming, annealing is especially important. Stainless steel work hardens quickly when cold formed, and the material often needs to be annealed between forming operations to keep it workable. As we previously mentioned, annealing also wipes away undesired ferromagnetism introduced by cold working in austenitic stainless steel.
The annealing process for stainless steel is typically completed in the mill, and the material is purchased in its annealed form. Austenitics can also be purchased in cold-worked conditions and are commonly referred to as quarter-hard, half-hard, full-hard stainless steels, to name a few.
Through Hardening
Martensitic and precipitation hardening-grade stainless steels can both be through hardened. Through hardening is a process that involves heating an alloy to enhance its physical properties and quenching to preserve those properties achieved during the heat treating process.
Through hardening is commonly used on stainless steel springs, seating components, hand tools, and other parts that are required to sustain heavy loads.
Case Hardening for Special Applications
Case hardening, nitriding, and FNC are used to increase wear resistance in special applications where carburization is required. These processes work to break down the oxide layer that forms on the surface of stainless steel to let carbon in to carburize the material effectively. Most all case hardening operations can decrease the corrosion resistance of stainless steel, but FNC lends the greatest degree of corrosion resistance in finished parts. Martensitic and austenitic stainless steels can both be carburized; the only downside is that they can reduce the corrosion resistance of the stainless material.
Case hardening is typically used for applications requiring greater wear resistance, most commonly for industrial food processing (grinders, pelletizers, etc.).
Annealing
Annealing is a controlled heating and cooling process that maximizes corrosion resistance and reduces hardness. It’s the first step in heat treating any stainless steel.
When cold forming, annealing is especially important. Stainless steel work hardens quickly when cold formed, and the material often needs to be annealed between forming operations to keep it workable. As we previously mentioned, annealing also wipes away undesired ferromagnetism introduced by cold working in austenitic stainless steel.
The annealing process for stainless steel is typically completed in the mill, and the material is purchased in its annealed form. Austenitics can also be purchased in cold-worked conditions and are commonly referred to as quarter-hard, half-hard, full-hard stainless steels, to name a few.
Through Hardening
Martensitic and precipitation hardening-grade stainless steels can both be through hardened. Through hardening is a process that involves heating an alloy to enhance its physical properties and quenching to preserve those properties achieved during the heat treating process.
Through hardening is commonly used on stainless steel springs, seating components, hand tools, and other parts that are required to sustain heavy loads.
Case Hardening for Special Applications
Case hardening, nitriding, and FNC are used to increase wear resistance in special applications where carburization is required. These processes work to break down the oxide layer that forms on the surface of stainless steel to let carbon in to carburize the material effectively. Most all case hardening operations can decrease the corrosion resistance of stainless steel, but FNC lends the greatest degree of corrosion resistance in finished parts. Martensitic and austenitic stainless steels can both be carburized; the only downside is that they can reduce the corrosion resistance of the stainless material.
Case hardening is typically used for applications requiring greater wear resistance, most commonly for industrial food processing (grinders, pelletizers, etc.).
Metallurgy Support for Stainless Steel
Our in-house metallurgists work with you to ensure the optimal heat treatment is selected and applied, factoring in alloy composition, part geometry, and application. Combining precise control with extensive metallurgical expertise, we help you achieve consistent performance and durability from their stainless steel components.
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