CAJ | 학술논문

利用XRD、SEM、TEM、EDS、金相显微镜、拉伸试验等方法研究了15-5PH不锈钢经400℃长期时效后组织及力学性能。随着时效时间延长，板条状马氏体逐渐变得细小，发生Spinodal分解，分解为富Cr相及富Fe相；大量ε-Cu相呈弥散析出；逆变奥氏体的量逐渐增多；粗大的析出相沿板条马氏体晶界分布；未溶解的NbC颗粒逐渐长大。随着时效时间的延长，抗拉强度先升高后下降，在1000 h时达到最大值1554 MPa；伸长率先下降后上升，在1000 h时下降到最小值4.8%；断面收缩率逐渐减小，试样断裂方式由韧性断裂向脆性断裂转变。
이용XRD、SEM、TEM、EDS、금상현미경、랍신시험등방법연구료15-5PH불수강경400℃장기시효후조직급역학성능。수착시효시간연장，판조상마씨체축점변득세소，발생Spinodal분해，분해위부Cr상급부Fe상；대량ε-Cu상정미산석출；역변오씨체적량축점증다；조대적석출상연판조마씨체정계분포；미용해적NbC과립축점장대。수착시효시간적연장，항랍강도선승고후하강，재1000 h시체도최대치1554 MPa；신장솔선하강후상승，재1000 h시하강도최소치4.8%；단면수축솔축점감소，시양단렬방식유인성단렬향취성단렬전변。
The microstructure, phase and mechanical properties of 15-5PH stainless steel long-term aged at 400℃ were studied by XRD, SEM, TEM, EDS, metallographic microscope and tension test, etc. As the aging process proceeded, the lath martensite becomes finer, and spinodaly decomposes into Cr-rich phase and Fe-rich phase, a large number of ε-Cu phase disperse precipitates, the amount of reversed austenite increases gradually;massive precipitate distributes on the lath martensite grain boundary, undissolved NbC grains grow up gradually. As the aging process proceeded ,the tensile strength increases firstly then decreases, and reaches the peak value of 1 554 MPa at 1 000 hours, the elongation value decreases firstly then increases,and reduces to the minimum value of 4. 8% at 1 000 hours. The reduction of area decreases gradually, and the fracture mechanisms of the specimens are transformed from ductile fracture to brittle fracture.