Development of functional materials by ECAE and subsequent heat treatment

为获得高强度塑性平面碳素钢微型螺杆材料，采用冷等通道转角挤压工艺及后续热处理工艺。通过重复ECAE工艺实现了晶粒度小于HIS的细化，提高了抗拉强度。在ECAE工艺后，进行了低温短时热处理，降低了拉伸强度，提高了总延伸率。2005财年，研究使用了常用的螺杆材料SWCH18A(0.16%C球化处理)和S15C。这两种材料都在室温下通过C路线进行了4次ECAE处理。经等温挤压处理后的试件在600℃的温度下分几个时间段进行退火处理，提高了延性。2006财年选用S25C、S35C、S45C等不同碳素钢，对热处理后的试件进行微螺杆加工，成功地生产出微螺杆。材料在室温下通过C路线进行4道ECAE处理。经等温挤压处理后的试件在600℃的温度下分几个时间段进行退火处理，提高了延性。采用Nakashimada公司为制造微型螺杆而设计的冷拔头进行微型螺杆的加工。微螺杆的制造结果，无论是否可能，都被用来判断通过变形和热处理制造的增强材料的成形性。这些知识体现在对热力耦合过程的优化中。

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.