After the drive gear broke, the quality record of the heat treatment sub-contractor was inspected. It was found that the active three-furnace was produced, and the tempering temperature displayed on the instrument automatic recording paper was 150160, and the holding time was 4h.
22 Material Analysis A sample was taken at the thread of the broken part of the driving gear to analyze the chemical composition of the material.
We also sampled the fractured and qualified drive gears at the same location and analyzed the hydrogen content separately. The results showed that the hydrogen content was 00001 (ie 1 ppm).
23 Metallographic and Fracture Analysis 231 Metallographic analysis The metal gear samples were taken from the thread of the broken part of the drive gear. The surface structure was martensite and retained austenite. The top carbide of the thread was grade 6 and the core structure was low. Carbon martensite.
In addition, the depth test was performed using a microhardness tester: the hardened layer at the top of the thread was 170 mm deep (measured to HV550), and the surface hardness was HV739 (ie, HRC61), and the carburized layer was evenly distributed.
The result of 232 fracture analysis is that the high fracture appearance of the fracture is characterized by dimple fracture, and the internal fracture is mainly the coexistence zone along the crystal and transgranular dimple.
24 Comparative Test and Analysis In order to further understand the effect of hydrogen embrittlement on the driving gear, we selected three sets of samples and tested the hydrogen content and mechanical properties under three different heat treatment conditions.
241 hydrogen content determination We made three sets of different heat-treated driving gears into 350mm samples for hydrogen content determination.
242 Mechanical properties determination Three sets of drive gears with different heat treatment conditions were respectively made into standard mechanical samples for measurement.
3 Results and discussion (1) From the scanning electron microscopy analysis of the fracture of the driving gear after carburizing and quenching, and the hydrogen content and comparison test of different heat treatment conditions, it is proved that whether quenching or increasing dehydrogenation and tempering in hydrogen protection atmosphere, or in non- Quenching in a salt bath furnace with hydrogen protection atmosphere has no significant difference in hydrogen content, and there is no significant difference in mechanical properties.
The fracture characteristics of the drive gear indicate that although quenched in a large amount of hydrogen atmosphere, it is not a hydrogen brittle fracture.
(2) From the heat treatment process, metallographic structure and depth measurement of the driving gear, it can explain the abnormal fluctuation of the heat treatment state, especially the insufficient tempering time and the effective protection of the thread during the heat treatment. The main cause of the drive gear breaking.
(3) After the above test, find out that the driving gear is broken, and strengthen the quality monitoring of the heat treatment. Adopting a series of effective corrective and preventive measures, more than one year of production practice has proved that the failure of the drive gear after heat treatment has been eliminated, the intrinsic quality of the product has been further improved and the reliability of the whole product has been guaranteed. .
Coupletech Co., Ltd. also supply Opto-mechanics products including optical mechanical adjustments racks, Pockels Cell holder ( Q-Switch holder), water-cooled modules ( water-cooled holder ), air-cooled modules ( air-cooled holder ), crystal mount, mirror mount ( Optical mount ), ploarizer holder and other optics-related products but also according to the customer's need to design and assemble the relevant systems.
For matching our EO Q-Switch, EO modulator, Optical Crystal and mirror, we offer all kinds of Kinematic Mounts, e.g. one dimensional, two dimensional, three dimensional and four dimensional adjusting mount, post, rails, brackets, bases, carries and clamps. Cooling module is suitable for higher power pulsed Q-Switched laser. Coupletech is constantly adding new opto-mechanics to better serve our customers.
Optical Stages,Optical Mount,Optical Rails,Pockels Cell Positioner,Crystal Holder,Rotation Kinematic Mounts
Coupletech Co., Ltd. , https://www.coupletech.com