Corrosion Resistance - TP410S AISI 410S Stainless Steel Tubes Pipes Tubing

410S Corrosion Resistance

The corrosion resistance of 410S stainless steel is similar to type 410. It resists corrosion in atmospheric conditions, fresh water, mild organic and mineral acids, alkalis and some chemicals. It’s exposure to chlorides in everyday activities (e.g., food preparation, sports activities, etc.) is generally satisfactory when proper cleaning is performed after exposure to use. The erosion-corrosion resistance of the nitrided and 473 K tempered AISI 410S steel was better than that of the AISI 410 and AISI 420 steels. This behavior was primarily due to the better corrosion resistance of the nitrided alloy, measured by potentiodynamic method. Scanning Electron Microscopy showed that intergranular corrosion of the AISI 410 and AISI 420 alloys was an important cause of mass loss, while it was not observed in the nitrided specimens.

A wide variety of techniques including alloying, coating deposition and thermo-chemical treating have been used to improve stainless steels’ corrosion-wear resistance. Guenbour et all studied the influence of alloying elements in corrcwion-abrasion of stainless steel in phosphoric acids containing chloride ions and SiC particles. Hodgkiess et al used a cerrnet coating material thermally sprayed onto stainless steel discs to enhance the resistance to corrosion-erosion in saline solution with silica particles. Berns at a improved the corrosion resistance of near net shape components for petrochemical industry by nitrogen addition in solid state. Synergism between corrosion and wear is extremely important for a wide range of applications regarding the use of stainless steel.

Three main routes are commonly used for obtaining high nitrogen steel: high-pressure melting, powder metallurgy* and solid-state alloying*. Melting under pressure is recommended for largescale fabrication but it rec~uirescomplex and costly equipment; powder metallurgy requires a hot isostatic pressing stage to obtain full-density components. Solid-state alloying allows changing the surface properties of several materials with minor modification of bulk properties. When dealing with wear and corrosion, solid state alloying is one of the most suitable processes due to reduced costs and simplicity.

It has been established that nitrogen improves the pitting corrosion resistance of stainless steels475’G, although the chemical andhr electrochemical mechanisms that explain this effect are not clearly established. Conversely, experimental results concerning the effect of nitrogen alloying on generalized corrosion resistance are, in many cases, contradictory.The beneficial effect of nitrogen on erosion resistance is commonly associated to solid solution hardening and second phase precipitation; hard chromium nitrides and carbonitrides provide good abrasion wear resistance, but in some cases the corrosion resistance is seriously reduced due to chromium depletion of metallic matrix.

High temperature nitriding of AISI 410S steel and heat treatments

AN 410S steel was gas nitrided in an experimental setup described in a previous work13. The specimens were placed in a tubular furnace and heated up to 1,473 K under 10-3Torr vacuum during 1 hour. High purity nitrogen was introduced in the fwace and the system was maintained at 0.25 MPa during 6 hours. At the end of the treatment the specimens were oil quenched and temperecl at 473 K during 1 hour under 0.15 MPa argon atmosphere. AISI 410 and AISI 420 steels were austenitized at 1,273 K during 1 hour under argon atmosphere, oil quenched and tempered at the same conditions used for the nitrided AISI 410S specimens. After the treatments, all the specimens were polished to 0.03*0.02 pm to standardize the surface finishing conditions for corrosion-erosion test.

Corrosion – Erosion tests

Corrosion-erosion experiments were performed in the test machine shown in Figure 1. It consists of a stainless steel vessel containing slurry made of substitute ocean water and 20°/0quartz particles (0.3-0.5 mm diameter). The specimens were fixed to electrically insulated metallic holders. The setup allowed the adjustment of impact angles to 45° or 90°. The slurry was impinged against the specimens’ surface by a polypropylene disk driven by an electronically controlled electric motor. The temperature of the slurry, as well as specimens’ mass losses and roughness changes were periodically measured. The slurry was renewed after every 96 hours test cy Effect of microstructure and chemical composition

Figure 4,shows the measured and calculated nitrogen profiles for the AISI 410S steel after gas nitriding at 1,473 K under 0.25 MPa NZatmosphere. The nitrogen content at the surface was 0.52°/0 before and 0.45?40after final polishing, due to material removal from the surface. The nitrogenenriched case was composed by a martensitic region with 1.1 mm thick, followed by a duplex ferrite/martensite region with ca 1 mm. No precipitates were detected by SEM analysis (Figure 5) allowing the assumption that all nitrogen is in solid solution in martensite and ferrite. This is supported by Thercle. Specific mass loss ~, defined as the quotient betweem the Cumulative mass loss AW (in gram) and the geometrical exposed surface S (in m2) was used to normalize the mass loss results.

mocalc@ simulation, which showed that the N2 e 2~]Y reaction is the only one occurring at 1,473 K under 0.25 MPa Nq pressure. All the nitride-forming reactions are inhibited at these conditions. Figure 6 shows a calculated phase diagram illustrating several solid-gas equilibrium conditions as a function of nitriding temperature under 0.25 MPa N2 pressure.

General Corrosion Behavior Compared With Other Nonaustenitic Stainless Steels*

5% Test
Solution at 120°F (49°C)

Corrosion Rate in Mils per Year and Millimeters per Year (mm/a)

Alloy 409

Alloy 410S

Alloy 420

Alloy 425 Mod

Alloy 440A

Alloy 430

Acetic Acid

0.88
(0.022)

0.079
(0.002)

1.11
(0.028)

4.79
(0.122)

2.31
(0.0586)

0.025
(0.0006)

Phosphoric Acid

0.059
(0.002)

0.062
(0.002)

0.068
(0.002)

0.593
(0.015)

0.350
(0.009)

0.029
(0.001)

*Hardened martensitic grades were tested after tempering at 400°F (204°C)

As shown in the above table, 410S has good corrosion resistance to low concentratiions of mild organic and mineral acids.