研究了不同温度条件AZ31镁合金型材的应力应变状态变化,探讨了在单向拉伸试验条件下,其力学性能、微观组织、断口形貌的变化规律.结果表明:随着温度的升高,屈服强度从室温的203 MPa下降到230℃时的125 MPa,显著减小;170℃时,镁合金屈服强度为152 MPa,抗拉强度为242 MPa,屈强比最小,塑性成形性能最好;170℃时,型材的微观组织中仍存在大量孪晶,主要发生在晶粒内部,而在晶界附近有少量的再结晶.断裂方式从25 ℃时的脆性解理断裂转变为120 ～ 170℃的准解理及韧窝混合断裂,再转变为210～230℃的韧窝韧性断裂.
The stress and strain states of AZ31 magnesium alloy profiles at different temperatures were studied,and the mechanical properties,microstructure and fracture morphology of the alloy were investigated by the uniaxial tension test.The results show that with the increasing of temperature,the yield strength of the magnesium alloy decreases from 203 MPa at room temperature to 125 MPa at 230 ℃.The yield strength and tensile strength of the magnesium alloy tensiled at 170 ℃ are 152 MPa and 242 MPa,respectively,the yield ratio is minimum and the plastic forming property is the best.There are still a large number of twins in the microstructure of the specimen tensiled at 170 ℃,which mainly occurs in grain interior,while a small amount of recrystallization near the grain boundaries.The fracture mode changes from brittle cleavage fracture at 25 ℃ to quasi cleavage and dimple mixed fracture at 120-170 ℃,and then to dimple fracture at 210-230 ℃.
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