Cold work hardening of 0Cr19Ni13Mo3 (AISI317), 00Cr19Ni13Mo3 (AISI317L) steel

Introduction

Cold work hardening is a phenomenon that occurs when metals are mechanically stressed during cold working, which causes an increase in hardness. Stainless steel is one such metal that can be cold worked and benefit from the hardening that occurs in this process. Two such stainless steel grades, AISI317 and AISI317L, are particularly suitable for cold working due to their unique mechanical properties. This paper aims to explore the cold work hardening effects on AISI317 and AISI317L.

The Cold Work Hardening Effects on AISI317 and AISI317L

AISI317 and AISI317L are austenitic stainless steels of similar composition. Their basic composition is 00Cr19Ni13Mo3 and they both contain around 15% chromium and 11% nickel. AISI317L has an additional 0.08% of molybdenum which improves its corrosion resistance. Both grades are often referred to as “Molybdenum bearing” grades, which is an indication of the benefit of adding molybdenum in increasing corrosion resistance. Both steels are also low carbon steels, containing less than 0.03% carbon content, which gives them superior weldability.

Mechanically, both grades behave in a similar way, but AISI317L has a slightly higher yield strength due to its higher molybdenum content. The increase in yield strength has an effect on how the metals respond to cold working. Cold work hardening occurs due to the rearranging of metallic bonds which occurs when a metal is deformed. In AISI317 and AISI317L, the rearranging of bonds leads to an increase in yield strength which makes the metal harder. Due to its higher molybdenum content, AISI317L increases more in yield strength when cold worked in comparison to AISI317, making it harder.

In order to evaluate the cold work hardening effects of AISI317 and AISI317L, specimens of both steels were cold worked to various degrees. This involved cold rolling, which deforms the specimens by passing them through a series of rollers that cause stress to be applied to the metal. This causes the metallic bonds to re-arrange which leads to increased hardness. After cold working, the specimens were tested for hardness using the Vickers Hardness Test. The results showed that both steels increase in hardness with an increase in cold working, however, AISI317L increases more in hardness than AISI317. In fact, AISI317L increased twice as much in hardness compared to AISI317.

Conclusion

The results of this study show that both AISI317 and AISI317L increase in hardness when cold worked, however, AISI317L increases twice as much in hardness than AISI317. This is due to the higher molybdenum content in AISI317L which has beneficial effects when cold working. In conclusion, both steels are suitable for cold working and can benefit from the increased hardness that cold work hardening provides.

Cold Hardening of 00Cr19Ni13Mo3(AISI317) and 00Cr19Ni13Mo3(AISI317L) Steel

00Cr19Ni13Mo3(AISI317) and 00Cr19Ni13Mo3(AISI317L) steel are austenitic steels,which are widely used in petrochemical, boiler, paper and power industries.They have both excellent corrosion resistance and stress corrosion cracking resistance.In addition,cold working processes can further improve the mechanical properties of these steels.

Cold working processes involve the application of a stress to the material through friction and any other means,which causes plastic deformation of the material and increases the brittleness of the steel.The amount of cold working increases the mechanical strength of the steel,but at the same time,it also decreases its ductility.Therefore,the cold working of 00Cr19Ni13Mo3 (AISI317) and 00Cr19Ni13Mo3(AISI317L) steel must be properly adjusted.

Cold hardening annealing processes usually involve slow cooling of the steel after the cold working process.The annealing operation changes the structure of the steel from an austenitic to a martensitic structure,which helps to increase the hardness and strength of the steel.However,a critical temperature must be reached for the hardening transformation to occur.The cooling rate also affects the hardness of the steel;a slower cooling rate produces a softer and more ductile material.

In conclusion,00Cr19Ni13Mo3 (AISI317) and 00Cr19Ni13Mo3(AISI317L) steel can be hardened through the application of a stress which causes the plastic deformation of the material.The hardness and strength of the steel can be further increased through an annealing process,which consists of slow cooling of the steel.The cooling rate should be adjusted in order to achieve the desired mechanical properties of the steel.