COMAC announced on August 1 that the domestically produced large aircraft C919 has completed the certification test flight.
On August 12, the domestic large aircraft C919 arrived in Kunming for the first time. The aircraft numbered B-001G took off from Dongying Airport at 9:50 in the morning and landed at Kunming Changshui Airport at 1:10. After landing, Kunming Changshui Airport welcomes C919 to the beautiful south of Caiyun with the highest civil aviation etiquette "passing the water gate"!
Aero-engines are known as the "jewel in the crown" of modern industry. Blades are the key components of aero-engines, which are subjected to high temperature, high cycle and even ultra-high cycle (>107) cyclic loads during their service life. In the process of material preparation, processing and use, parts and components usually inevitably have various types of defects. Therefore, revealing the high-temperature high-cycle and ultra-high-cycle fatigue properties and defect susceptibility of titanium alloys has important scientific significance and engineering application value.
The microstructure computational mechanics research group of the State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, revealed that high-cycle fatigue cracks of TC17 titanium alloy for aero-engine blades at high temperature (200℃ and 400℃) originated from the surface or inside of the sample (Fig. 1). Crack initiation is caused by cracking of the oxygen-rich layer or oxide exfoliation (Fig. 1a-1g), and internal crack initiation is induced by grain refinement due to dislocation interactions (Fig. 2). Based on the experimental results, a competitive model of surface crack initiation and internal crack initiation of TC17 titanium alloy at 400 ℃ is proposed.
a: SEM image, the short line is the extraction position; b: SEM observation results along the principal stress direction at position b in a; c-e: reverse pole diagram, phase diagram and TEM picture of the section along the principal stress direction at position c in a; fand g: are the dark field image of area 1 and the enlarged image of area 2 in E, respectively. FIG. 2 Microstructure observation results of fatigue fracture roughness of smooth specimens at 400℃ (σa =520MPa, R=-1, Nf=1.0x106)
The research results are of great value for understanding the high-temperature high-cycle and ultra-high-cycle fatigue failure mechanisms of titanium alloys, as well as fatigue strength prediction of titanium alloys with defects.
Haida can provide you with related instruments:
Metallurgical microscope features
The micro-motorized control platform provides controlled movement in three directions: X, Y, and Z
Touch control screen, saving space and flexible control
NOMIS Plus Motorized Microscopic Imaging System Software
HD-U831 Metallographic Microscope
This instrument has safe, reliable and stable test performance, and has the advantages of simple touch screen operation, accurate test and high reliability. It is the diligent pursuit of every Haida person to let every company have high-quality inspection instruments!
Contact Person: Ms. Kelly