Study Of Microstructure And Hot Strength On ZG12Cr22Ni12 Hot Resistent Steel

Gas turbines are often used for long time at 700℃.It starts and stops frequently, which does great damage to materials.ZG12Cr22Ni12 austenite hot resistant steel has good mechanical properties, particularly, anti-high-temperature oxidation performance and anti-corrosive performance. The structure and hot strength of ZG12Cr22Ni12 austenite hot resistant steel were studied through high temperature short time tensile experiment, room temperature tensile and impact test after heating at 700℃for long time, high temperature oxidation experiment. It has significance and provides essential data for material components design, intensity design and craft design. It has practical significance for application.Rp0.2,Rm,A and Z decreases with the increasing temperature during high temperature short time tensile test. However, Rp0.2 and Rm decrease quickly at 600℃. A and Z increase quickly at 600℃.E reduces during the whole test with the exception of 700℃.While heated for long time at 700℃,Rp0.2 and Rm continued to reduce. The bottom point is at 25h,after 25h they both raises and Z firstly increases and then decreases.E continued to rise. Impact energy and hardness reduces. There exists chain like precipitates and circular precipitates. Circular precipitates are most at 75h, however chain like precipitates most at 100h.There are M23C6 during oxidation at 600℃.The content of M23C6 increases with the oxidation time expanding. After 50h,Cr18.93Fe4.07C6 transforms to Cr23C6 completely. Oxidized dynamics partition conforms to the straight line rule separately.There appears compact Cr2O3 membrane on the oxidized surface at 700℃.Besides, the thickness of Cr2O3 film increases with the extension of oxidizing. Film's thickness reduces and M23C6 separates out at 100h.Oxidized dynamics conforms to the parabola rule.Although oxidation resistance is good for austenitic hot resistant steel at 600℃,yet precipitates(M23C6)influence material's performance and drop steel's intensity. There is compact Cr2O3 oxidation film on the surface at 700℃,which is protective. Few precipitates would not reduce intensity greatly.Referring to high temperature oxidation microstructure, precipitates increases gradually from 5h to 50h at 600℃.The precipitates(M23C6) increases from 25h to 100h at 700℃and they separate out in grain boundary and triangle grain boundary.