Effect of Controlled Cooling on Microstructure and Mechanical Properties of H-Beam

Based on ANSYS, an analytical model was established for H-beam during controlled cooling. The temperature fields during controlled cooling and air cooling were analyzed and the microstructure and mechanical properties for different parts of H-beam were discussed in detail. After the H-beam was controlled cooled for 4. 5 s, its mean surface temperature decreased from 850 to 460 °C, and the lowest and the highest temperatures were measured at edge of flange and at R corner, respectively. Whereas, for the H-beam air-cooled for 30 s, the mean temperature at R corner and web was 700 and 540 °C, respectively. The microstructures for different parts of H-beam consisted of ferrite and pearlite, and the grain size at R corner was coarser than those at flange and web. The difference of yield and tensile strengths of web, flange and R corner was within 30 MPa, and the elongation was similar. The changes of microstructure were in good agreement with that of temperature field. In addition, the results show that the uniformity of microstructure and mechanical properties can be improved by increasing water flow rate at R corner.