Development of functional materials by ECAE and subsequent heat treatment

为获得高强度、高韧性平面碳钢微螺钉材料，采用等通道转角挤压工艺进行了冷挤压及后续热处理。通过反复ECAE处理，获得了晶粒尺寸小于1 μ m的晶粒细化效果，提高了抗拉强度。在ECAE工艺之后，进行低温短时间热处理，通过该热处理，抗拉强度降低，总延伸率增加。在2005财年，研究中使用了通常用作螺钉材料的SWCH 18A（0.16%C，球化处理）和S15 C。两种材料均在室温下通过途径C进行ECAE处理4次。ECAE处理后的试样在600 ℃下分阶段退火，提高了塑性。对热处理后的试件进行了微型螺纹的制造，成功制造出微型螺纹。2006财年，选择了不同的含碳钢S25 C、S35 C和S45 C。材料在室温下通过途径C ECAE处理4次。ECAE处理后的试样在600 ℃下分阶段退火，提高了塑性。利用日本中岛田株式会社设计制造微型螺纹的冷镦机进行微型螺纹的加工，并将其加工结果作为变形和热处理强化材料成形性的判断依据。这些知识在热力过程组合优化中得到了体现。

To obtain materials for micro screw which was high strengthened plane carbon steel with ductility, a cold ECAE (equal channel angular extrusion) process and following heat treatment were conducted. Grain refinement with grain size less than him was achieved by repeated ECAE process and tensile strength was increased. After ECAE process, low temperature, short time heat treatment, by which tensile strength become lower and total elongation increased, was carried out.In FY 2005, SWCH18A (0.16%C with spheroidizing treatment) which is usually used as a material of screws and S15C were used in investigation. Both materials were ECAE processed to 4 passes via route C at room temperature. ECAE Processed specimens were annealed at 600 ℃ in several periods, then ductility were improved. Manufacturing micro screw was conducted to specimen after heat treated and succeed in producing micro screw.In FY 2006, Different carbon contained steels, S25C, S35C and S45C were selected. Materials were ECAE processed to 4 passes via route C at room temperature. ECAE Processed specimens were annealed at 600 ℃ in several periods, then ductility were improved. Producing micro screw was conducted by the cold header, that was design to manufacture micro screw, made by nakashimada co. ltd.The results of producing micro screw, whether it was possible or not, was used for judging of formability in enhanced materials fabricated by deformation and heat treatments. These obtained knowledge were reflected in the optimization for combination of thermo-mechanical process.