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石墨易切削钢是顺应易切削无铅、低硫这一发展趋势而产生。具有亚共析成分的钢种其石墨化过程一直较难,因此开发该钢种的关键是促进其石墨化过程。研究表明,通过合理的成分设计和工艺处理,可以在较短的时间内钢中C原子的石墨化。石墨化退火时,C原子除了能在析出相上形成石墨外,还能自发形核及长大形成石墨。经石墨化退火后,试验钢的组织主要由铁素体+石墨+少量渗碳体组成,其中,石墨粒子的尺寸较为细小,分布也较为均匀,渗碳体主要以球状的形式分布铁素体晶粒晶界及晶内。抗拉强度和伸长率分别为595 MPa和33%,表现较高的强度和较好的塑性。
Graphite free cutting steel is easy to follow cutting lead-free, low-sulfur development of this trend. Steel with sub-eutectoid composition has been difficult to graphitize, so the key to developing this steel is to promote its graphitization process. The research shows that the graphitization of C atoms in steels can be carried out in a relatively short period of time through rational composition design and process. Graphitization annealing, C atoms in addition to the formation of graphite in the precipitation phase, but also spontaneous nucleation and growth to form graphite. After graphitizing and annealing, the microstructure of the test steel is mainly composed of ferrite + graphite + a small amount of cementite, in which the size of the graphite particles is relatively small and the distribution is relatively uniform. The cementite mainly distributes ferrite in a spherical form Grain grain boundaries and intragranular. Tensile strength and elongation were 595 MPa and 33%, respectively, showing higher strength and good ductility.