Coat-hanger dies are widely used in the extrusion of plate and sheet, since it can achieve uniform velocity attribution on the outlet according to balancing the distribution of flow through the die. A failure ABS extrusion die of a petrochemical company is studied in this paper. The results show that the pressure drop in the die exceed the maximum allowable value, which is the main cause of die failure, in addition to the exceeded pressure drop the fluctuation of the velocity on the outlet is too large, which would lead to poor quality of product. The work in the paper provides guidance for the future die design and optimization.
This paper present the state of the art review on the effect of the various heat treatments on fatigue strength and fracture toughness of the different tool steels. The different researchers used the experimental tests like thermal fatigue test, thermo-mechanical fatigue (TMF) test for calculation of fatigue strength and threepoint bend tests for fracture toughness of the tool steels.
Burst of a reactor occurred in an explosion accident during the production of antistatic agent process. According to the results of site survey, the current regulations and standards as well as the requirements of the accident investigation group, the reason of burst was discussed by failure analysis of the shell and bolts.
In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The continuous
cooling transformation (CCT) diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative ségrégations.
Tungsten carbide alloyed with cobalt (WC/Co) shows unique characteristics like high strength at elevated temperature and high mechanical and chemical resistance that makes carbide tools appropriate for cutting, drilling, mining and machining operation. A whole failure study is revealed within the paper. This study also discusses the failure mode of a tungsten carbide tools, its prediction and remedies.
The study shows that considerable reserves still exist for increasing the service times of CrN-coated dies for Al hot extrusion. The main reasons for the decreased service times are revealed and explained regarding the selected CrN-coated die for hot extrusion, i.e. why the service time of the coated-die is not in accordance with the wear resistance of the CrN-coating. The shaping of the bearing surface and presence of the scratches, size and amount of nonmetalic inclusions in the die steel, nodular defects in the CrN-coating, as well as thicknesses uniformity of CrN-coatings along the bearing surface, are relevant influential parameters.
L’étude expérimentale confiée par EDF au Cetim a eu pour objectif de déterminer l’influence du mode de chargement sur la vitesse de propagation en fatigue de fissures transverses circonférentielles et d’évaluer les éventuels effets d’échelle.
Les compétences du Cetim s’expriment à travers sa capacité à maîtriser l’ensemble des technologies mécaniques. Les cas qui sont présentées ici exposent des exemples de réalisations menées pour ses clients tant à titre collectif qu’à titre individuel. Elles témoignent de la capacité du Cetim à proposer une offre globale et personnalisée de prestations autant pour les grands donneurs d’ordre que pour les petites entreprises.
This paper mainly investigates the fracture problem of U71Mn rail flash-butt welding joint. The analysis results show that the welding joint is fatigue fracture, and the fracture surface morphology is the cleavage fracture characteristics.