Postcarburizing Thermal Treatments

Carburizing ◽  
1999 ◽  
pp. 171-198
Keyword(s):  
Retained Austenite ◽  
Standard Procedure ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Related Factors ◽  
Fracture Behaviors ◽  
Fatigue And Fracture ◽  
Potential Problems ◽  
Numerous Data ◽  
Effects Of Aging

Abstract This chapter familiarizes readers with tempering and refrigeration treatments and their effect on case-carburized parts. It explains how tempering makes such parts easier to machine, more structurally and dimensionally stable, and more durable in certain applications. It identifies key process parameters and provides test data showing how they affect hardness, yield strength, bending and contact fatigue, and fracture toughness. It also addresses potential problems stemming from process-related factors such as the presence of hydrogen and the effects of aging and grinding. In regard to refrigeration, the chapter explains that it is not uncommon for subzero treatments to be included in the production of carburized parts whether as a standard procedure or optional step. Subzero cooling promotes the transformation of retained austenite to martensite, thereby increasing surface hardness and reducing the propensity of quenched carburized steels to burn and crack during surface grinding. The chapter includes numerous data plots and tables showing how the various treatments influence hardness, wear resistance, tensile properties, and fatigue and fracture behaviors.

Retained Austenite

Carburizing ◽  
1999 ◽  
pp. 77-97
Keyword(s):  
Wear Resistance ◽  
Residual Stresses ◽  
Tensile Properties ◽  
Retained Austenite ◽  
Fracture Behaviors ◽  
Fatigue And Fracture

Abstract This chapter addresses the issue of retained austenite in quenched carburized steels. It explains why retained austenite can be expected at the surface of case-hardened components, how to estimate the amount that will be present, and how to effectively stabilize or otherwise control it. It presents detailed images and data plots showing how retained austenite appears and how it influences hardness, tensile properties, residual stresses, fatigue and fracture behaviors, and wear resistance.

scholarly journals Potential problems of partial resection for colitis-associated cancer in a patient with ulcerative colitis: case report

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Yuki Horio ◽  
Motoi Uchino ◽  
Takako Kihara ◽  
Toshihiro Bando ◽  
Ryuichi Kuwahara ◽  
...  
Keyword(s):  
Ulcerative Colitis ◽  
Endoscopic Resection ◽  
Ileal Pouch ◽  
Standard Procedure ◽  
Partial Resection ◽  
Total Proctocolectomy ◽  
Potential Problems ◽  
Partial Colectomy ◽  
A Site ◽  
Anal Site

Abstract Total proctocolectomy and an ileal pouch-anal anastomosis are recommended as the standard procedure for ulcerative colitis (UC)-colitis-associated cancer (CAC). However, several studies have reported the partial colectomy and endoscopic resection of UC-CAC in recent years. We present a surgical case of UC-CAC that was detected at a site that had not been diagnosed preoperatively, and we report potential problems of partial colectomy and endoscopic resection through this case. Considerations of synchronous and metachronous cancer/dysplasia are important before partial resection is planned for CAC in UC. Moreover, it should be noted that endoscopic resection at the anal site can be a risk factor for pouch surgery failure due to fibrosis after resection.

scholarly journals Establishment of health management package for native sheep of Bangladesh

2016 ◽  
Vol 3 (1) ◽  
pp. 151-155 ◽  
Author(s):  
KBM Saiful Islam ◽  
Md Ershaduzzaman ◽  
Md Nuruzzaman Munsi ◽  
Md Humayun Kabir ◽  
Sompa Das ◽  
...  
Keyword(s):  
Health Management ◽  
Standard Procedure ◽  
Disease Status ◽  
Related Factors ◽  
In Vivo Evaluation ◽  
Betel Leaf ◽  
Native Sheep ◽  
Sheep Production

The present study was designed to explore the disease status of sheep in Bangladesh with the aim of developing health management package for sheep for better and efficient sheep production in Bangladesh. Both retrospective and prospective investigations on the incidence and prevalence of different diseases of sheep have been conducted in the study areas. Information on the disease related factors like health status, sex and age, vaccination, deworming, etc. were collected. Samples (faeces, blood, etc.) were collected from the diseased/dead animals and preserved following the standard procedure. Faecal samples were examined to determine the parasitic loads and faecal as well as blood samples were examined to determine any protozoan infection present in the study animals. Samples from diarrhoeic animals were studied to isolate and identify causal organisms. Antibiotic resistance and sensitivity studies of the aetiological agents responsible for common infectious diseases in sheep were also conducted in order to suggest the most suitable antibiotic to treat the concerned diseases in the field. Since helminthic infections, diarrhea, pneumonia and foot rot were found to be the mostly occurring health hazards in sheep of all ages, especial attempts were made to develop herbal based novel approaches to treat and control major intestinal helminthic infestations of sheep. However, gentamicin and ciprofloxacin were found most effective antibiotics and recommended to use in diarrhoeal cases in the field. On the other hand, methanol extract of mahogany seeds (100 mg), betel leaf (100 mg) and dodder (100 mg) were found significantly effective against 100% worms in 2 hours in vitro and thus recommended to be used in the field against helminthic infection in sheep. Therefore, a health management package for native sheep of Bangladesh can be designed using the present findings with some fluctuations for different sites after doing the in vivo evaluation of the medicinal plants used in this experiment.Res. Agric., Livest. Fish.3(1): 151-155, April 2016

Fatigue Performance of Low Pressure Carbonitrided 20MnCr5 and SAE 8620 Steel Alloys

2021 ◽  
Author(s):  
Larissa Vilela Costa ◽  
Vincent Lelong ◽  
Dennis Beauchesne ◽  
Robert L. Cryderman ◽  
Kip O. Findley
Keyword(s):  
Retained Austenite ◽  
Prior Austenite ◽  
Endurance Limit ◽  
Fatigue Testing ◽  
Surface Hardness ◽  
Low Pressure ◽  
Austenite Grain Size ◽  
Steel Alloys ◽  
Austenite Grain ◽  
Prior Austenite Grain

Abstract Low pressure carbonitriding and pressurized gas quenching heat treatments were conducted on four steel alloys. Bending fatigue tests were performed, and the highest endurance limit was attained by 20MnCr5+B, followed by 20MnCr5, SAE 8620+Nb, and SAE 8620. The differences in fatigue endurance limit occurred despite similar case depths and surface hardness between alloys. Low magnitude tensile residual stresses were measured near the surface in all conditions. Additionally, nonmartensitic transformation products (NMTPs) were observed to various extents near the surface. However, there were no differences in retained austenite profiles, and retained austenite was mostly stable against deformation-induced transformation to martensite during fatigue testing, contrasting some studies on carburized steels. The results suggest that the observed difference in fatigue lives is due to differences in chemical composition and prior austenite grain size. Alloys containing B and Nb had refined prior austenite grain sizes compared to their counterparts in each alloy class.

High cycle fatigue and fracture behaviors of CrMoV/NiCrMoV dissimilar rotor welded joint at 280 °C

2020 ◽  
Vol 786 ◽  
pp. 139473
Author(s):  
Wen-Ke Wang ◽  
Yan Liu ◽  
Yang Guo ◽  
Zhen-Zhen Xu ◽  
Jie Zhong ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Welded Joint ◽  
Cycle Fatigue ◽  
Fracture Behaviors ◽  
Fatigue And Fracture

scholarly journals Evaluation of contact fatigue risk of a carburized gear considering gradients of mechanical properties

Friction ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1039-1050
Author(s):  
Wei Wang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Jinyuan Tang ◽  
Chenxu Jiang
Keyword(s):  
Mechanical Properties ◽  
Fatigue Failure ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Engineering Practice ◽  
Case Hardening ◽  
Failure Risk ◽  
Spalling Failure ◽  
Carburized Gear

AbstractCarburized gears are widely used in geared machines such as wind turbines. Contact fatigue problems occur in engineering practice, reducing reliabilities of machines. Contact fatigue failures are related to many factors, such as gradients of mechanical properties of the hardening layer. In this work, an elastic-plastic contact model of a carburized gear is developed based on the finite element method to evaluate contact fatigue failure risk, considering variations in hardness and strength. The Dang Van multiaxial equivalent stress is calculated via Python coding within the Abaqus framework. The gradient of yield strength along the depth from case to core is considered. The concept of local material fatigue failure risk is defined to evaluate the probability of pitting failure. The effects of design factors, such as the case hardening depth (CHD), surface hardness, and contact pressure on fatigue failure risk, are studied. As the CHD increases or the surface hardness decreases, the risk of deep spalling failure reduces. The increase in surface hardness leads to a decreased risk of pitting failure, while the variation in CHD hardly affects the pitting failure risk.

scholarly journals Rolling Contact Fatigue Life of Case−Hardened Steel Treated by Shot Peenings with Shot Diameters of 0.05 mm and 0.30 mm

2011 ◽  
Vol 86 ◽  
pp. 645-648 ◽  
Author(s):  
Lei Wang ◽  
Guang Liang Liu ◽  
Masanori Seki ◽  
Masahiro Fujii ◽  
Qian Li
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Shot Peening ◽  
Fine Particle ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Hardened Steel ◽  
Rolling Contact ◽  
Contact Fatigue Life

In order to investigate the influence of different shot peenings on the rolling contact fatigue life of case−hardened steel, the thrust type rolling contact fatigue test was performed with a ball−on−disk contact tester. In this study, the case−hardened steel disks were treated by the fine particle peening with a shot diameter of 0.05 mm and the normal shot peening with a shot diameter of 0.30 mm. The surface hardness and the surface compressive residual stress of the test disks were increased by these peenings. On the other hand, the surface roughness of the test disks was increased by the normal shot peening, and was decreased by the fine particle peening. The rolling contact fatigue test showed that the rolling contact fatigue life of the test disks was improved by the fine particle peening, and was not improved by the normal shot peening. The rolling contact fatigue life of the test disks became longer as their surface roughness became smaller. Therefore, it follows from this that the fine particle peening, which can provide the increase in surface hardness and the decrease in surface roughness, is good for the increase in the rolling contact fatigue life of case−hardened steel.

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