Maximum service temperatures in air for stainless steels

Introduction

The maximum oxidation service temperatures for heat resisting steels is shown 'for guidance only' in table B.2 of EN 10095.
Although helpful, this only covers the steels specifically designed for heat resisting applications.

An alternative guide is shown in the ASM Specialty Handbook 'Stainless Steels', where a wider range of stainless steel grades is covered.

A comparison of these maximum service temperatures under intermittent or cyclic oxidation conditions (where protective oxide films produced may be likely to crack, hence reducing the useful service life) is summarized in this article, but it must be stressed that, these figures can only be used for guidance.

Selection of stainless steels for oxidation resistant service should also consider the the design strength requirements at the intended service temperature.

Austenitic stainless steel types

There are some apparent contradictions in the data, where EN 10095 suggests that the 321 type (1.4541 / 1.4878) is 'inferior' to the 316 and 304 types, as shown in the ASM data.

Based on the chromium content of these three types, the maximum service temperatures would be expected to be the same.
(The titanium stabilised 321 type would in fact normally be preferred, as its elevated temperature strength should be marginally better.)

Ferritic, duplex and martensitic stainless steel types

The ferritic types may be limited, in practice, to lower temperatures as they have lower strengths at elevated temperatures than the austenitic types. The ferritic types can also suffer from embrittlement with extended exposure to temperatures above about 450 °C.

Duplex stainless steels can also be prone to embrittlement and so although their chromium levels would suggest they may be useful steels for elevated temperature service. This steel family is limited in the European pressure vessel standard EN 10028-7 to a maximum temperature of 250 °C.

The martensitic types are not considered here.
These steels are usually selected for their hardness and strength, which will be reduced when their tempering heat treatment temperature is exceeded, thus limiting their usefulness for elevated temperature service.

Summary of maximum service temperatures

Grade		Main Alloying Elements (%)		Max. Service Temp. °C	Source
AISI	EN	Cr	Others	.	.
Ferritic types		.	.	.	.
405	1.4002	12	0.2 Al	815	ASM
.	1.4724	12	1.0 Al	850	EN 10095
430	1.4016	17	.	870	ASM
.	1.4742	17	1.0 Al	1000	EN 10095
.	.	.	.	.	.
446	1.4749	26	0.15-0.20 C, 0.2 N	1100	EN 10095
Austenitic types		.	.	.	.
304	1.4301	18	8 Ni	870	ASM
321	1.4541	18	9 Ni	870	ASM
.	1.4878	18	9 Ni	850	EN 10095
316	1.4401	17	11 Ni, 2 Mo	870	ASM
309	1.4833	22	12 Ni	1000	EN 10095
310	1.4845	25	20 Ni	1050	EN 10095
.	1.4835	20	10 Ni, 1.5 Si, 0.15 N, 0.04 Ce	1150	EN 10095
330	1.4886	18	34 Ni, 1.0 Si	1100	EN 10095

 

 

 

Source: http://www.bssa.org.uk/