Effect of Prior Cold Deformation on the Stability of Retained Austenite in GCr15 Bearing Steel

In this work, the effect of prior cold deformation on the stability of retained austenite in GCr15 bearing steel was investigated after quenching and tempering treatment. The thermal stability was evaluated by calculating thermal activation energy for decomposition of retained austenite using differential scanning calorimeter. The mechanical stability was investigated according to the strain-induced martensitic transformation behavior of retained austenite under the standard compression testing. It is found that the prior cold deformation not only accelerates the carbide dissolution during the austenitization process but also contributes to the carbon partitioning in the tempering stage due to the higher density of phase boundaries, which results in the improvement of the thermal stability of retained austenite. Due to the enhanced carbide dissolution, the higher carbon content in the prior austenite will intensify the isotropic strain of martensitic transformation. As a consequence, the film-like retained austenite is likely to form under a higher hydrostatic pressure and thus shows a higher mechanical stability. Additionally, it is noteworthy that the benefits of the prior cold deformation to the stability of retained austenite would be saturated when the cold deformation degree is larger than 40%.

Life Prediction of Newly Developed Ferritic Stainless Steels for Automotive Muffler

Corrosion mechanism of automotive mufflers was investigated by SEM （scanning electron microscope） and XRD （X-ray diffractomer） analysis. 409L and newly developed 439M steels were evaluated in terms of condensate corrosion tests for 5 periods, 10 periods and 20 periods separately. The relative lifetimes of 409L and 439M steels were predicted according to the extreme value analysis method and pitting corrosion models. Modelling studies dem- onstrated that the predicted relative lifetime of 439M ferrite stainless steel is 6.8 times that of 409L steels. The extreme value analysis method was also successfully used in the road test. The estimated maximum corrosion depth of the 439M muffler is 0. 55 ram.

Deep learning for automatically predicting early haematoma expansion in Chinese patients

Background and purpose Early haematoma expansion is determinative in predicting outcome of intracerebral haemorrhage(ICH)patients.The aims of this study are to develop a novel prediction model for haematoma expansion by applying deep learning model and validate its prediction accuracy.Methods Data of this study were obtained from a prospectively enrolled cohort of patients with primary supratentorial ICH from our centre.We developed a deep learning model to predict haematoma expansion and compared its performance with conventional non-contrast CT(NCCT)markers.To evaluate the predictability of this model,it was also compared with a logistic regression model based on haematoma volume or the BAT score.Results A total of 266 patients were finally included for analysis,and 74(27.8%)of them experienced early haematoma expansion.The deep learning model exhibited highest C statistic as 0.80,compared with 0.64,0.65,0.51,0.58 and 0.55 for hypodensities,black hole sign,blend sign,fluid level and irregular shape,respectively.While the C statistics for swirl sign(0.70;p=0.211)and heterogenous density(0.70;p=0.141)were not significantly higher than that of the deep learning model.Moreover,the predictive value for the deep learning model was significantly superior to that of the logistic model of haematoma volume(0.62;p=0.042)and the BAT score(0.65;p=0.042).Conclusions Compared with the conventional NCCT markers and BAT predictive model,the deep learning algorithm showed superiority for predicting early haematoma expansion in ICH patients.

Effects of Sub-zero Celsius Treatment and Tempering on the Stability of Retained Austenite in Bearing Steel

In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional quenched and tempered treatment, sub-zero Celsius treatment obviously decreases the volume fraction of retained austenite. Moreover, the mechanical stability of retained austenite was enhanced due to the accumulation of compressive stresses in retained austenite after sub-zero Celsius treatment and tempering. Meanwhile, the morphology of retained austenite changed from film-like to blocky with austenitization temperature increasing, and the mechanical stability of film-like retained austenite is higher than that of blocky one. The DSC results showed that the activation energy of retained austenite decomposition slightly increased through sub-zero Celsius treatment and tempering. This result may probably be ascribed to partitioning of carbon during tempering. However, the temperature at which retained austenite starts to decompose is unchanged.

Life-saving therapy for complete traumatic hemipelvectomy:a case report

To the Editor:Traumatic hemipelvectomy(THP),which was first described by Turnbull in 1978,is an unstable ligamentous or osseous hemipelvic injury that involves rupture of the pelvic neurovascular bundle(either open or closed integuments).[1]THP is a rare and catastrophic injury that is usually caused by high-energy trauma,as in a traffic,motorcycle,and machinery-related accident,and is accompanied by pelvic fractures.[2]THP usually leads to other associated injuries.[3]The mortality associated with open pelvic fracture is approximately 40%,while the mortality associated with THP may reach as high as 100%.[4]However,few studies describe a standardized approach for handling this fatal trauma.