Optimization of Strength and Toughness for Hot-Forged Bainitic Medium Carbon Steel Using RSM

Document Type

Article

Publication Date

2021

Abstract

This work presents the experimental results and statistical analysis of the strength and toughness for an isothermally heattreated medium carbon steel of composition 0.415% C, 1.67% Si, 1.22% Mn, 0.97% Cr, and 0.29% Mo, with varying Al contents in the range (0.00-1.16%) by response surface methodology (RSM). The effect of aluminum content, as well as the isothermal treatment at 300°C for 24–120 hrs in terms of varying the holding time is studied and correlated with the mechanical properties of the steel and state of art findings. Design of experiments and ANOVA were implemented for statistical analysis using Design Expert software. The results show the predicted range of combinations of Al wt.% and holding time that yields the highest values of the responses (Yield strength, ultimate tensile strength, impact energy and hardness). Moreover, the regression equations for each response and the optimum values of the controllable factors to maximizes the responses values are introduced.

Comments

The addition of variant percentages of Al in the range (0.00–1.16%) to medium carbon steel of composition 0.415% C, 1.67% Si, 1.22% Mn, 0.97% Cr, and 0.29% Mo; followed by isothermal heat treatment at 300C for 24–120 hrs result significant enhancement in the mechanical properties and the highest strength of 1603 MPa with the highest elongation of 8.8% elongation and highest impact toughness of 48 J was achieved for 0.65% Al after holding for 120 hrs at 300C. ANOVA analysis of the experimental data predicts the process parameters for optimization to be 0.49 wt% Al and isothermal holding time of 49.4 hrs.

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