# Mechanical Properties of ASTM A572 Grades 50 and 60 Steels at High Temperatures
## 1 Introduction
These experimental studies with the steady-state test included the stress-strain relationships at strains of 0.05, 0.1, and 0.2% for both the A572 Gr. 50 and 60 steels. Results from the stress-strain relationship at elevated temperatures are used to suggest the strength reduction factors with convenient regression equations for both the A572 Gr. 50 and 60 steels. To compare the mechanical properties of A572 Gr. 60 to those of mild steel, Gr. 50 steel was selected in this study to quantify and compare the above properties. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Group** & **Type** & **Grade** & \
\begin{tabular}{c} **Yield Strength** \\ \(\left(f_{y},\textbf{MPa}\right)\) \\ \end{tabular} &
\begin{tabular}{c} **Tensile Strength** \\ \(\left(f_{w},\textbf{MPa}\right)\) \\ \end{tabular} & **Author** \\ \hline \multirow{3}{*}{Index} & EN1993-1-2 & \multicolumn{3}{c}{Eurocode Standard (EN1993-1-2) [9]} \\ \cline{2-6}  & NIST\_2016 & \multicolumn{3}{c}{NIST Regression Equation [26]} \\ \cline{2-6}  & AISC\_2016 & \multicolumn{3}{c}{A1 SC Standard [27]} \\ \hline \multirow{6}{*}{MS} & SS400\_1 & SS400 (SS235) & 235 & 400 & Kwon (2001) \\ \cline{2-6}  & SS400\_2 & & Kwon (2007) \\ \cline{2-6}  & SM490 & SM490 (SM355) & 355 & 490 & [PERSON] (2007) \\ \cline{2-6}  & A572 Gr. 50\_Kodur & \multirow{2}{*}{ASTM A572 Grade 50} & \multirow{2}{*}{345} & \multirow{2}{*}{450} & [PERSON] (2016) \\ \cline{2-6}  & A572 Gr. 50\_Test & & & & \\ \cline{2-6}  & A992 & ASTM A992 & 345 & 450 & [PERSON] (2015) \\ \cline{2-6}  & S350 GD+Z & S350 GD+Z & 350 & 420 & \\ \cline{2-6}  & S3552 JH\_50\(\times\)50\(\times\)3 & \multirow{2}{*}{S355J2H} & \multirow{2}{*}{355} & \multirow{2}{*}{470–630} & \multirow{2}{*}{[PERSON] (2004)} \\ \cline{2-6}  & S355J2H\_80\(\times\)80\(\times\)3 & & & & \\ \cline{2-6}  & S355J2H\_100\(\times\)100\(\times\)3 & & & & \\ \cline{2-6}  & Mild steel & Mild steel & 400–460 & 550 & [PERSON] (2006) \\ \hline \multirow{6}{*}{HS} & A572 Gr.60\_Test & ASTM A572 Grade 60 & 415 (Min) & 520 & This study \\ \cline{2-6}  & S460N\_SST & \multirow{2}{*}{S460N} & \multirow{2}{*}{460} & \multirow{2}{*}{540–720} & [PERSON] (2013) \\ \cline{2-6}  & S460N\_TST & & & & \\ \cline{2-6}  & S690\_SST & & & & \\ \cline{2-6}  & S690\_TST & & & & \\ \cline{2-6}  & HSS & High-strength steel & 780–820 & 850 & [PERSON] (2006) \\ \cline{2-6}  & S960\_SST & & & & \\ \cline{2-6}  & S960\_TST & & & & \\ \cline{2-6}  & S960\_TST & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Types of steel according to yield strength. Figure 1: The yield strength reduction factor: (**a**) different steels at elevated temperatures from previous studies; (**b**) according to the steel grade, highlighting the MS, HSS, and VHSS zones. Figure 3: The elastic modulus reduction factor: (**a**) different steels at elevated temperatures from previous studies; (**b**) according to the steel grade, highlighting the MS, HSS, and VHSS zones. Figure 2: The tensile strength (ultimate strength) reduction factor: (**a**) different steels at elevated temperatures from previous studies; (**b**) according to the steel grade, highlighting the MS, HSS, and VHSS zones.