In addition to a small amount of stable carbides and nitride, high -performance iron stainless steel has a complete iron microcoscin microstructure. The unique characteristic of this ferrite structure is that it has a good chloride stress corrosion and fracture performance, but its toughness is limited. The large -breaking surface or grain effect and brittle secondary phase will further reduce its toughness. Due to the limited toughness, these steel species are usually not produced into a middle thick plate. The development of these steel species is to obtain resistance to resistance corrosion and erosion resistance of 18-8 stainless steel at the price below the price of high nickel Ages alloys. They are generally used only for the heating pipe material or thin plates. The heat treatment does not cause them to harden, but in the state of fire, they show the strength of many Austeenan stainless steel. The following table lists the main forging iron type steel species in the order of increased oxide erosion performance.
| Grade | Type | C | N | Cr | Ni | Mo | Cu | other | Corrosion -resistant equivalent |
| S44400 | F1 | 0.025 | 0.035 | 17.5~19.5 | 1 | 1.75~2.50 | - | Ti，Nb | 23 |
| S44626 | 0.06 | 0.04 | 25.0~27.0 | 0.5 | 0.75~1.50 | - | Ti | 27 | |
| S44627 | 0.01 | 0.015 | 25.0~27.0 | 0.5 | 0.75~1.50 | - | Nb | 27 | |
| S44635 | F2 | 0.025 | 0.035 | 24.5~26.0 | 3.5~4.5 | 3.5~4.5 | - | Ti，Nb | 36 |
| S44660 | 0.03 | 0.04 | 25.0~28.0 | 1.0~3.5 | 3.0~4.0 | - | Ti，Nb | 35 | |
| S44735 | F3 | 0.03 | 0.045 | 28.0~30.0 | 1 | 3.6~4.2 | - | Ti，Nb | 40 |
| S44800 | 0.01 | 0.02 | 28.0~30.0 | 2.0~2.5 | 3.5~4.2 | - | 40 |
F1-type ferrite stainless steel, such as E-BRITE26-1, has a local corrosion resistance similar to 316 stainless steel, but its ability to resist stress corrosion is much better than the latter. This good stress corrosion fracture performance makes it useful for thermal concentrated alkali solution and chloride solution.
F2-type iron stainless steel, such as Sea-Cure, is designed for the local corrosion of the warm seawater, and is widely used in the seawater cooling condenser for power plants. Due to their high chromium content, molybdenum and nickel content is moderate, it also has good corrosion resistance to strong organic acid and oxidized or medium -reduced inorganic acid. However, the nickel in these steels reduces the performance of chloride's stress corrosion and breaks, and increases the sensitivity to the harmful secondary phase. All these ferrite stainless steels can be resistant to the corrosion of the sodium chloride test solution. However, because its nickel content is 0.5 % to 4.2 %, the stress corrosion of the magnesium chloride test solution may not be resistant.
F3-type ferrite stainless steel, like A6 high-performance Austenite stainless steel, is designed to achieve the highest level of comprehensive performance of ferrite stainless steel in this category. Corrosion and acid resistance.
