Hoge temperatuur eigenschappen roestvrij staal

Stainless steel have good strength and good resistance to corrosion and oxidatie 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 warmtewisselaar, super-heaters, ketel, 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 treksterkte en treksterkte 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 neerslag, 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).

Carbide precipitation 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 (Titanium 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 duplex roestvast staal 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 hardheid en treksterkte at room temperature, but retains its desirable mechanische eigenschappen at operating temperatures.

Table 1 Short Term Treksterkte vs Temperatuur (in gegloeide toestand, behalve voor 410)

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

Table 2 Generally Accepted Service Temperaturen

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 oppervlak 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.

Verwante referenties:
Gebruik van roestvast staal onder hoge temperatuur raadpleeg de tabel
Corrosiebestendige roestvast stalen buis
Corrosiebestendigheid van roestvast stalen buizen
Temperatuursinvloeden op metaalsterkte
Roestvrijstalen buizen op hoge temperatuur
Roestvrijstalen buizen op hoge temperatuur
Roestvrij staal met hoog temperatuurbezit
Hittebestendige roestvrij stalen buizen
Gelaste roestvast stalen pijp
U-bocht roestvrij stalen buizen
Warmtewisselaarbuizen
Duplex roestvast stalen buizen
Ketelbuizen, Condensorbuizen
De gegolfde Naadloze Buis van de Roestvrij staalpijp
DIN 2391 Naadloze Buizen van Precisiestaal
EN 10305-1 E215 E235 E355 Naadloze Precisiestaal Buizenbuizen
Niet-zuurbestendige roestvrij stalen buis
Het heldere Ontharden Van Roestvrij Staal Buizen
Normen voor buizen en pijpen voor hoge temperaturen
Hoge temperatuur verandering roestvrij staal Mechnical eigenschappen
Hittebestendig roestvrij staal en corrosiebestendig roestvrij staal - klepstalen, ijzerlegeringen superlegeringen
Risico's van vonken in explosieve gasatmosferen