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A high carbon high chromium type combining stainless steel properties with excellent hardness after heat treatment.
440B is very similar to the 440C grade but with a slightly lower carbon content, it attains a lower hardness than 440C but has slightly better corrosion properties. Its corrosion resistance properties are similar to 410 stainless steel, with optimum corrosion resistance of 440B achieved with a temper below 400°C. For 440B to achieve best corrosion resistance all surfaces must be free of scale, foreign particles, lubricants and coatings applied for drawing and heading. With its high carbon content 440B stainless steel annealed bar has similar machining characteristics to a high speed steel annealed grade.
Suitable for applications requiring a combination of excellent wear resistance with moderate corrosion resistance. 440B stainless steel is commonly used in the oil, gas, marine, food and medical industries. Typical applications include valve components, knives, bearings, surgical tools and cutlery.
Heat slowly and uniformly to 1180°C, allowing sufficient time for the steel to become heated through. Be careful not to overheat as this can cause a loss of toughness and ductility. Do not forge below 1010°C reheating if necessary. After forging cool slowly in furnace or thermoinsulating material, then anneal immediately. Air cooling after forging 440B may cause cracking.
Heat uniformly to 840-875°C. Soak and cool very slowly in the furnace.
Heat the 440B to 1010-1070°C, fully soak and quench in warm oil or air cool. Be careful not to overheat or full hardness will not be obtained.
When tempering 440B a Rockwell hardness of 58 HRc can be obtained. Temper for at least one hour. Tempering above 400°C is not recommended as this can cause a reduction in corrosion resistance and impact properties.
Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of 440B stainless steel.