16.4Variation of Mechanical Properties of Steel with Temperature

IS 800:2007, General Construction in Steel — Code of Practice

Last Updated 29 Oct 2026

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16.4.1 Variation of Yield Stress with Temperature

The influence of temperature on the yield stress of steel shall be taken as follows for structures of mild steels and high strength low alloy steels:

$\frac{f_{y}(T)}{f_{y}(20)}=\frac{905-T}{905} \leq 1.0$

where

$f_{y}(T)=$ yield stress of steel at $T^{\circ} \mathrm{C}$

$f_{y}(20)=$ yield stress of steel at $20^{\circ} \mathrm{C}$ (room temperature), and

$T=$ temperature of the steel in ${ }^{\circ} \mathrm{C}$ .

This relationship is shown by Curve 1 in Fig. 24.

Yield Stress and Modulus of Elasticity Ratios for Steel at Elevated Temperatures YEILD STRESS RATIO

Figure description:

Yield Stress and Modulus of Elasticity Ratios for Steel at Elevated Temperatures

YEILD STRESS RATIO OR MODULUS OF ELASTICITY RATIO VS STEEL TEMPERATURE (T °C

Legend

CURVE 1 : YEILD STRESS RATIO — color: black; symbol: solid line
CURVE 2 : MODULUS OF ELASTICITY RATIO — color: black; symbol: solid line

Annotations

215 (text_label - position: x = 215)
T = 215 transition for Curve 1 (vertical_line - position: x = 215)

STEEL TEMPERATURE (T °C)	YEILD STRESS RATIO (CURVE 1)	MODULUS OF ELASTICITY RATIO (CURVE 2)
0	1.0	1.0
200	1.0	0.9
215	1.0	0.89
400	0.8	0.8
600	0.47	0.55
800	0.11	0.2
900	0.0	0.1
1000	null	0.0

Notes: Note the misspelling of 'YIELD' as 'YEILD' in the source graph. Curve 1 remains constant at 1.0 until 215°C, while Curve 2 begins to decrease immediately from 0°C. Both curves intersect at a ratio of 0.8 at 400°C.

FIG. 24 VARIATION OF MECHANICAL PROPERTIES OF STEEL WITH TEMPERATURE

For temperature less than 215°C no reduction in the yield stress need to be considered.

16.4.2 Variation of Modulus of Elasticity with Temperature

The influence of temperature on the modulus of elasticity shall be taken as follows for structures of mild steels and high strength low alloy steels:

$\frac{E(T}{E(20} = 1.0 + \left. \frac{T}{2000 \left. \ln \left( \frac{T}{1100} \right) \right.} \right.$

when $0^{\circ} \mathrm{C}<T \leq 600^{\circ} \mathrm{C}$

$\frac{690\left(1-\frac{T}{1000}\right)}{T-53.5}$

when $\quad 600^{\circ} \mathrm{C}<T \leq 1000^{\circ} \mathrm{C}$

$\begin{aligned} E(T) & =\text { modulus of elasticity of steel at } T^{\circ} \mathrm{C} \\ \text { and }\end{aligned}$
$\begin{aligned} E(20) & =\text { modulus of elasticity of steel at } 20^{\circ} \mathrm{C} \\ & \text { (room temperature). }\end{aligned}$

This relationship is shown by curve 2 in Fig. 24.

16.4.3

For special steel with higher temperature resistance, such as TMCP steels, the manufacturer's recommendation shall be used to obtain the variation of yield strength and modulus of elasticity of steel with temperature.