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Introduction
Austenitic stainless steels are alloys composed of lower levels of carbon, combined with higher levels of chromium, nickel and molybdenum giving excellent corrosion resistance, strength and machinability. One such example is 0Cr17Ni12Mo2N (S31658). In this paper, the mechanical properties of S31658 steel, such as tensile strength, yield strength, and elongation, are discussed in detail.
Chemical Composition
S31658 is a type of austenitic stainless steel with a chemical composition as follows (wt. %): C: 0.08; Mn: 2.00; Ni: 11.00-13.00; Si: 0.50; P: 0.040; N: 0.12-0.22; S: 0.03; Cr: 17.00-19.00; Mo: 2.00-2.50.
Temperature-Strength Relationship
It is usually observed that the strength of an alloy increases as the temperature increases and falls as the temperature decreases. This is also true in the case of S31658. The ultimate tensile strength (UTS) of this alloy at room temperature is reported to be 690 MPa, and its 0.2% proof strength is 580 MPa. With the increase of temperature up to 200 °C, the UTS and 0.2% proof strength of S31658 undergo a decline, and reach a maximum at 2150 K (1877 °C). At this temperature, the UTS and 0.2% proof strength of S31658 are 651 MPa and 536 MPa, respectively. As the temperature continues to increase beyond 1877 °C, both UTS and 0.2% proof strength start to decline and reach the minimum of 600 MPa and 525 MPa at 2450 K (2177 °C).
Influence of Cold Working on Mechanical Properties
Cold working plays an important role in altering the mechanical properties of a metal. In the case of S31658 austenitic stainless steel, cold working can cause a significant increase in the strength of the metal, but at the same time decreases its ductility. In general, with increase in the amount of cold work, the yield and tensile strengths of S31658 increases, whereas its elongation decreases.
Effect of Heat Treatment on Mechanical Properties
Heat treatment is another effective method to modify the mechanical properties of S31658. When the alloy is subjected to various heat treatments such as solution annealing or stress relieving, its mechanical properties are modified significantly. After solution annealing, the alloy displays improved properties such as higher tensile strength, higher yield strength, and improved ductility. On the other hand, after the stress relieving treatment, the alloy displays improved properties such as higher tensile strength and improved ductility.
Conclusion
In this paper, the mechanical properties of 0Cr17Ni12Mo2N (S31658) austenitic stainless steel have been discussed in detail. It has been observed that at room temperature, the ultimate tensile strength (UTS) and 0.2% proof strength of S31658 are 690 MPa and 580 MPa, respectively. With the increase of temperature up to 1877 °C, the UTS and 0.2% proof strength undergo a decline, and reach a maximum of 651 MPa and 536 MPa, respectively. Cold working and heat treatment processes were found to be effective methods to modify the mechanical properties of the alloy.
