High Temperature Mechanical Properties of 0Cr18Ni9(AISI304) and 00Cr19Ni10(AISI304L)

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High temperature mechanical properties of 00Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L)

Stainless steel is an extremely versatile material with a great variety of properties and possible uses. This makes it popular in both domestic and industrial applications. Two of the most widely-used stainless steel grades, 00Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L), are particularly sought after due to their high corrosion resistant properties and cost-effectiveness. While they have similar compositions, they possess different physical, thermal, and electrical properties. In this article, we will focus particularly on their high temperature mechanical properties.

Temperature significantly affects the mechanical behavior of materials. 00Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L) remain ductile up to temperatures of 400-500 °C, beyond which creep and annealing are encountered. This gradually decreases the strength of the material, leading to a decrease in hardness and tensile strength at elevated temperatures. The yield strength of 00Cr18Ni9 (AISI304) drops from 176.6 MPa at 25 °C to 7 MPa at 500 °C, and the ductility drops from 28.4% to 0.4% over the same range. The same reduction in strength and ductility is observed in the 00Cr19Ni10 (AISI304L) as well, although the initial yield strength is slightly lower at 138 MPa. It is important to note that the austenitic stainless steel grades have good resistance to creep at high temperatures, making them suitable for structural applications such as boilers and pressure vessels.

The fatigue strength of 00Cr18Ni9 (AISI304) is also relatively good at high temperatures, although it does degrade over time. This property makes it suitable for fatigue-prone applications such as valve stems. The fatigue strength of 00Cr19Ni10 (AISI304L) is slightly lower than that of 00Cr18Ni9 (AISI304), but it is still adequate for many commercial applications.

Elevated temperatures can also lead to corrosion in stainless steel grades. 00Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L) have good corrosion resistance at temperatures up to 400-500 °C, after which they start to degrade. The reduction in corrosion resistance is due to the breakdown of the passive layer that protect the surfaces of the materials at lower temperatures. This can be mitigated through proper surface composition and proper heat treatment, allowing these grades to be used in some high temperature applications.

In conclusion, 00Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L) are two popular stainless steel grades with good properties at high temperatures. They are relatively inexpensive and possess high tensile and yield strengths at room temperature. However, at elevated temperatures, the strength and ductility of these grades degrade significantly, and their corrosion resistance also begins to decrease. Care must be taken to ensure that proper material selection and surface processing are conducted, in order to achieve desired properties and to reduce the risk of corrosion and other mechanical failures.

Introduction

AISI304 and AISI304L are two kinds of austenitic stainless steels materials with high chromium (Cr) and nickel (Ni) content. This paper aims to discuss the mechanical properties of AISI304 and AISI304L at high temperatures.

Mechanical Properties

The mechanical properties of AISI304 and AISI304L at high temperatures are greatly varied. AISI304 has higher strength at high temperatures than AISI304L. At 800℃， AISI304 has a yield strength of ~80MPa and an ultimate tensile strength of ~140MPa. By comparison,AISI304L has a yield strength of ~60MPa and an ultimate tensile strength of ~103MPa. Similarly, AISI304 is found to have a higher hardness at high temperatures than AISI304L. AISI304 has a Vickers hardness ~245 HV, whereas the Vickers hardness of AISI304L is ~203 HV at 800℃.

Conclusion

In conclusion, AISI304 possesses higher strength and hardness than AISI304L at high temperatures.These properties make AISI304 a better choice for applications that require high mechanical properties at high temperatures, such as boiler and automobile parts.