The impact of freeze – thaw and steaming treatments on the drying performance of <i>Eucalyptus urophylla</i> × <i>E. grandis</i> wood

To address the issues of high drying stress, severe cracking, and poor dimensional stability in eucalyptus wood drying, this study explored the impacts of freeze–thaw treatment (FT) and steam treatment (ST) on the wood's drying rate, moisture content (MC) distribution, shrinkage, and drying stress. The main findings are as follows: Both FT and ST enhanced the drying rate of specimens, with FT having a better improvement (P < 0.05). The drying rate of the FT group was the highest, 41% higher than that of the control group, while the ST group increased by 6.70% compared to the control. During drying, the MC of specimens showed a gradient distribution. FT and ST significantly reduced the moisture content difference (ΔMC) within the wood specimens. At 50% MC, FT significantly reduced ΔMC by 13% compared to the control; at 40% MC, ST reduced it by 11% (P < 0.05). Both treatments decreased the shrinkage of eucalyptus specimens, and FT had a better effect. The maximum shrinkage was significantly reduced by 42% in the FT group and by 21% in the ST group compared to the control (P < 0.05). Moreover, FT and ST reduced the residual stress of eucalyptus specimens, and FT was more effective.