固溶冷却方式对GH4220合金螺栓力学性能的影响

Effect of solution cooling method on mechanical properties of GH4220 alloy bolts

将GH4220合金螺栓在1220℃固溶处理冷却阶段的冷却方式由标准热处理制度的空冷改为缓慢冷却(24 min冷却至1100℃保温1 min,之后空冷),利用SEM、微机控制电子万能试验机观察合金的晶界形态及力学性能的变化。结果表明,相比标准热处理制度,缓慢冷却处理以后,晶界锯齿状特征明显,晶界由平直晶界变为弯曲晶界。室温抗拉强度由标准热处理制度的1004 MPa提升至1143 MPa,提高了13.8%,950℃高温抗拉强度由标准热处理制度的478 MPa提升至532 MPa,提高了11.3%;940℃高温应力持久断裂时间提升尤为明显,由标准热处理制度的38.2 h提高到51.7 h,提高了35%。

Cooling method of GH4220 alloy bolts in the cooling stage of solution treatment at 1220 ℃ was changed from the air cooling of the standard heat treatment system to slow cooling(cooling to 1100 ℃ within 24 min and holding for 1 min, and then air cooling), the grain boundary morphology and mechanical properties of the alloy were observed by means of SEM and computer-controlled electronic universal testing machine. The results show that compared with the standard heat treatment system, the grain boundary after the slow cooling treatment has obvious zigzag characteristics, and the grain boundary changes from a straight grain boundary to a curved grain boundary. The room temperature(950 ℃) tensile strength is increased by 13.8% from 1004 MPa under the standard heat treatment system to 1143 MPa. Similarly, the high temperature tensile strength is increased by 11.3% from 478 MPa under the standard heat treatment system to 532 MPa. The high temperature(940 ℃) stress lasting fracture time increases significantly, from 38.2 h under the standard heat treatment system to 51.7 h, which rises by 35%.