Effect of Rare Earth Elements on Erosion Resistance of Nitrocarburized Layers of 38CrMoAl Steel

Effect of rare earth elements (RE) on erosion resistance of nitrocarburized layer of 38CrMoAl steel was investigated. The results indicate that significant improvement occurs in erosion resistance of nitrocarburized 38CrMoAl steel by introducing RE during nitrocarburizing processing as compared with conventional nitrocarburizing processing. Results of mechanical testing show that both hardness and impact toughness of RE-nitrocarburizing layer of 38CrMoAl steel increase as compared with the conventional one. Optical microscopy reveals that there is improvement in the nitrocarburized layer attributed to the introduction of RE, which results in improvement in erosion resistance. Surface morphology observation of tested samples reveals that predominantly furrow-like peelings from plastic deformation are observed for RE nitrocarburizied 38CrMoAl steel, while the furrow-like peeling with initial cross crack and large grinding peelings were observed for conventionally nitrocarburized samples.

Parametric Collaborative Design of Network-based Mechanical Products

Aiming at the problems of low-level information sharing, slow transmission and repetitive work in the designing process of product series, the internet-oriented parametric collaborative design method is proposed, in which the problems of sharing conflict and network heterogeneous in the distributed collaborative design are analyzed, and the construction method of collaborative design platforms based on PDMWorks Workgroup is put forward. Through studying the mechanism of roles distribution and function allocation and data concurrency control, the communication mechanism of internet-oriented collaborative design is formulated. On the basis of structure features of overhead travelling crane, through combining parametric variant design with collaborative design, internet-oriented parametric collaborative design system of overhead travelling crane is developed and verified through main girder design. In the paper, the internet-oriented parametric collaborative design method is proposed, aiming to solve the problems of low-level information sharing, slow transmission and repetitive work in the designing process of product series. The problems of sharing conflict and network heterogeneous in the distributed collaborative design are analyzed. The construction method of collaborative design platforms based on PDMWorks Workgroup is put forward. The communication mechanism of internet-oriented collaborative design is formulated, through studying the mechanism of roles distribution and function allocation and data concurrency control. On the basis of structure features of overhead travelling crane, through combining parametric variant design with collaborative design, internet-oriented parametric collaborative design system of overhead travelling crane is developed and verified through main girder design.