退火态钨钾合金的微结构演化及力学性能研究

Study on Microstructure Evolution and Mechanical Properties of Annealed W-K Alloy

钨基材料因其高熔点、相对优异的高温性能被广泛应用于核聚变及搅拌摩擦焊接领域。以钨钾合金为对象,研究退火态钨钾合金的微观组织演变及相应力学性能。结果表明:原始态钨钾合金的平均晶粒尺寸、平均硬度分别为2.08μm、4.38 GPa,800℃抗拉强度423 MPa、断裂伸长率50%。锻态钨钾合金的再结晶温度在1425~1435℃。当退火温度低于1425℃,钨钾合金以回复为主。1425℃退火态样品平均晶粒尺寸为2.23μm,较原始态的增大22%,平均硬度下降4%至4.21 GPa,800℃抗拉强度为393 MPa,断裂伸长率为34%。当退火温度达到1500℃,材料完成再结晶,晶粒出现明显粗化,平均晶粒尺寸为178.17μm,是原始态样品平均晶粒尺寸的85倍,平均硬度为3.60 GPa,较原始态下降18%,800℃抗拉强度仅为208 MPa,断裂伸长率为44%。

Tungsten-based materials have good prospects as candidate materials for nuclear fusion devices and friction stir welding tools due to their high melting point and relatively excellent high-temperature mechanical properties.The microstructure and corresponding mechanical properties of as-received and annealed W-K alloy were investigated.The results show that the average grain size of as-received W-K alloy is 2.08μm,with the average hardness values of 4.38 GPa.When the ambient temperature is up to 800℃,the ultimate tensile strength of as-forged W-K alloy is 423 MPa,accompanied with fracture elongation being 50%.The recrystallization temperature of the forged W-K alloy ranges from 1425℃to 1435℃.Recovery dominates inside the W-K material as the annealing temperature is lower than 1425℃.Compared with corresponding data of as-received samples,the average grain size increases by 22%to 2.23μm while the average hardness decreases by 4%to 4.21 GPa with the tensile properties being characterized by the ultimate tensile strength reduces to 393MPa and fracture elongation descends to 34%as W-K alloy is annealed at 1425℃.When the annealing temperature is up to 1500℃,the recrystallization is finished along with grain coarsening.The average grain size is 178.17μm,which is 84 times bigger than average grain size of original samples,meanwhile the average hardness drops by 18%to 3.60 GPa compared with as-forged samples.When the ambient temperature rises up to 800℃,the ultimate tensile strength of the W-K alloy annealed at 1500℃decreases dramatically to 208 MPa,and the fracture elongation is 44%.