Propiedades a alta temperatura Acero inoxidable

Stainless steel have good strength and good resistance to corrosion and oxidación at elevated temperatures. Stainless steel are used at temperatures up to 1700° F for 304 and 316 and up to 2000 F for the high temperature stainless grade 309(S) and up to 2100° F for 310(S). Stainless steel is used extensively in intercambiador de calor, super-heaters, caldera, feed water heaters, valves and main steam lines as well as aircraft and aerospace applications.

Figure 1 gives a broad concept of the hot strength advantages of stainless steel in comparison to low carbon unalloyed steel. Table 1 shows the short term resistencia a la tracción y límite elástico vs temperature. Table 2 shows the generally accepted temperatures for both intermittent and continuous service.

With time and temperature, changes in metallurgical structure can be expected with any metal. In stainless steel, the changes can be softening, carbide precipitaciones, or embrittlement. Softening or loss of strength occurs in the 300 series (304, 316, etc.) stainless steel at about 1000° F and at about 900° F for the hardenable 400 (410<, 420, 440) series and 800° F for the non-hardenable 400 (409, 430) series (refer to Table 1).

Precipitación de carburo can occur in the 300 series in the temperature range 800 – 1600° F. It can be deterred by choosing a grade designed to prevent carbide precipitation i.e., 347 (Cb added) or 321 (Titanio added). If carbide precipitation does occur, it can be removed by heating above 1900° and cooling quickly.

Hardenable 400 series with greater than 12% chromium as well as the non-hardenable 400 series and the acero inoxidable dúplex are subject to embrittlement when exposed to temperature of 700 – 950° F over an extended period of time. This is sometimes call 885F embrittlement because this is the temperature at which the embrittlement is the most rapid. 885F embrittlement results in low ductility and increased dureza y resistencia a la tracción at room temperature, but retains its desirable propiedades mecánicas at operating temperatures.

Table 1 Short Term Resistencia a la tracción vs Temperatura (en estado recocido excepto 410)

* tratado térmicamente by oil quenching from 1800° F and tempering at 1200° F

Table 2 Generally Accepted Service Temperaturas

It may seem to be illogical that the “continuous” service temperature would be higher than the “intermittent” service temperature for the 300 series grades. The answer is that intermittent service involves “thermal cycling”, which can cause the high temperature scale formed to crack and spall. This occurs because of the difference in the coefficient of expansion between the stainless steel and the scale. As a result of this scaling and cracking, there is a greater deterioration of the superficie than will occur if the temperature is continuous. Therefore the suggested intermittent service temperatures are lower. This is not the case for the 400 series (both ferritic and martensitic grades). The reason for this is not known.

Referencias relacionadas:
Utilización del acero inoxidable en condiciones de alta temperatura consulte la tabla
Tubo de acero inoxidable resistente a la corrosión
Resistencia a la corrosión de los tubos de acero inoxidable
Efectos de la temperatura en la resistencia de los metales
Tubos de acero inoxidable para altas temperaturas
Tubos de acero inoxidable para altas temperaturas
Acero inoxidable con propiedades a altas temperaturas
Tubos de acero inoxidable resistentes al calor
Tubos soldados de acero inoxidable
Tubos de acero inoxidable curvados en U
Tubos intercambiadores de calor
Tubos de acero inoxidable dúplex
Tubos de caldera, tubos de condensador
Tubo corrugado de acero inoxidable sin soldadura
DIN 2391 Tubos de acero de precisión sin soldadura
EN 10305-1 E215 E235 E355 Tubo de acero de precisión sin soldadura Tubos
Tubo de acero inoxidable no resistente a los ácidos
Recocido brillante Tubos de acero inoxidable
Tubos para altas temperaturas Normas
Propiedades técnicas del acero inoxidable para altas temperaturas
Aceros inoxidables resistentes al calor y aceros inoxidables resistentes a la corrosión-Aceros para válvulas,Superaleaciones Iron Baes
Riesgos de chispas en atmósferas de gases explosivos