(大連理工大學(xué) 材料科學(xué)與工程學(xué)院 三束材料改性國家重點(diǎn)實(shí)驗(yàn)室，大連 116023)
摘 要: 研究AZ31鎂合金不同方向的力學(xué)性能、疲勞裂紋擴(kuò)展行為和單峰過載效應(yīng)以及載荷比對疲勞裂紋擴(kuò)展速率的影響。結(jié)果表明：不同方向材料的抗拉強(qiáng)度相當(dāng)，而屈服強(qiáng)度差別較大；不同方向疲勞裂紋擴(kuò)展行為存在差異，是由于屈服強(qiáng)度不同所致，歸一化后差別消失；當(dāng)應(yīng)力強(qiáng)度因子范圍相同時(shí)，疲勞裂紋擴(kuò)展速率隨載荷比的降低而降低；單峰過載時(shí)，疲勞裂紋向前擴(kuò)展一段距離并偏離原擴(kuò)展方向，導(dǎo)致隨后裂紋擴(kuò)展遲滯，這是由于過載增大殘余壓應(yīng)力和裂紋出現(xiàn)偏折的結(jié)果。
關(guān)鍵字: AZ31鎂合金；疲勞裂紋；單峰過載效應(yīng)；屈服強(qiáng)度
（School of Materials Science and Engineering, State Key Laboratory of Materials Modification by Laser,Ion and Electron Beams, Dalian University of Technology, Dalian 116023, China）
Abstract:The tensile property, fatigue crack growth behavior and the effect of single overload of AZ31 magnesium alloy and load on fatigue crack growth rate were investigated under different directions. The results show that the ultimate strength has little difference, while the yield strength diverges under various directions, and the difference of fatigue crack growth behavior attributes to the yield strength, which disappears after unification. Under identical ∆K, the fatigue crack growth rate decreases with the decrease of stress ratios. During single overloading, the fatigue crack continues to the propagate and deflects from its original path, and it induces subsequent crack growth retardation due to the increase of compressive residual stress and crack deflection.
Key words: AZ31 magnesium alloy; fatigue crack; single overload effect; yield strength
