Abstract:
The present invention relates to a rigid plasticity processing method for a metal pipe provided to improve mechanical stiffness such as internal pressure fatigue resistance inside and outside a metal pipe, vibration fatigue resistance, cavitation and scratch resistance, and durability while maintaining the shape of the metal pipe, which is manufactured or is being manufactured within a predetermined range; and a rigid plasticity processing apparatus therefore. The rigid plasticity processing method of the metal pipe comprises: a step of compressing a metal pipe wall facing an outer mold or an inner mold or to load the metal pipe between the outer and inner molds spaced apart from the wall of the metal pipe, wherein either the outer mold facing the outer wall of the loaded metal pipe along the circumference of the outer wall or the inner mold facing the inter wall of the loaded metal pipe along the circumference of the inner wall is divided into a plurality of segments, and a gap between the outer and inner molds increased or decreased by a pressurizing drive unit, thereby compressing the wall of the metal pipe; a step of compressing either the outer mold or the inner mold to the faced wall of the metal pipe; and a step of rotating either the outer mold or the inner mold or to pass the metal pipe through the gap between the outer and inner molds.
Abstract:
The present invention relates to a porous metallic material having a hierarchical cell structure and a manufacturing method thereof for producing a product with a cell structure which has desired microstructures, desired product density, and desired mechanical properties by controlling the hierarchical distribution of pores and the structural properties of a porous metallic material. The manufacturing method of the porous metallic material having the hierarchical cell structure includes (a) a step of manufacturing rod-shaped specimens using a core material and a covering metallic material which covers the core material; (b) a step of forming a first bundle by gathering the specimens and manufacturing a composite of different materials, in which the rod-shaped specimens with a uniform size are hierarchically distributed, by extruding the first bundle in the longitudinal direction; and (c) a step of removing the core material from the composite of the different materials. The rod-shaped specimens, the composite of the different materials, and a multi-material of different materials obtain directivity and form the hierarchical distribution inside the product. The present invention manufactures the metallic material by removing the male core material manufactured by controlling various conditions so that the directivity, the size, and the density (the distribution of the pores in comparison with cross sectional area) of the pores can be varied. Therefore, the present invention can obtain a porous metallic material with a hierarchical cell having desired properties such as weight and mechanical strength.
Abstract:
PURPOSE: A method for measuring the micro local strain of a material is provided to measure original properties of the material as the surface of a sample is not damaged and patterns are transformed in transformation. CONSTITUTION: A method for measuring the micro local strain of a material comprises: a step (S10) of forming patterns with points of a nano unit on the surface of a sample; a step (S20) of obtaining digital images before and after transformation of the sample; and a step (S30) of analyzing the digital images with a digital image analysis technique. The patterns are formed by heat treatment after forming a thin film on the surface of the sample. The shape and the size of the patterns become different according to a microstructure and the measurement magnification of the sample. [Reference numerals] (S10) Step of forming patterns with points of a nano unit on the surface of a sample; (S20) Step of obtaining digital images before and after transformation of the sample; (S30) Step of analyzing the digital images with a digital image analysis technique
Abstract:
본 발명은 서로 다른 2종 이상의 금속편을 원주방향으로 번갈아 배치한 후 압축비틀림 공정을 통해 재료에 원주방향의 소성변형을 가하여 층과 층 사이에서 좋은 금속결합을 갖도록 하고, 동시에 복합화 과정에서 큰 전단변형이 가해져 재료의 결정립 미세화를 통해 재료의 강도, 경도, 내마모성 등의 기계적 물성을 향상시킬 수 있는 새로운 조직구조를 갖는 복합재료의 제조방법에 관한 것이다. 본 발명에 따른 복합재료의 제조방법은, (a) 2종 이상의 서로 다른 금속재료로 이루어진 단위 금속편을 준비하는 단계; (b) 상기 2종 이상의 단위 금속편을 상,하부 다이가 구비된 금형에 원주방향으로 배치하는 단계; (c) 장입된 금속편에 상,하부 다이를 이용하여 압축응력을 가하는 단계; 및 (d) 가압된 상태에서, 상기 상,하부 다이 중 일방 또는 양방을 회전시켜 회전력을 가하는 단계;를 포함한다.