【摘要】 激光辐照后合金铸铁产生了熔化与未熔化两种情况,依据热传导分析,表面层的冷却速率为10~4～10~5℃/s,并可以自淬火,不同的层深、具有不同的加热温度与冷却速率。因之,不同层深将具有不同的组织,熔凝层由渗碳体骨架及粗大马氏体针的铸态组织组成,HM750左右,过热层由渗碳体骨架、粗大马氏体针及相当数量的残余奥氏体组成,比较详细地讨论了石墨在该区的作用。相变硬化区是颗粒状渗碳体、细针马氏体及隐晶马氏体,HM900左右,热影响区是对基体的高温回火。更多还原

【Abstract】 Laser irradiation can treat the cast alloy iron as both of melted and unmelted conditions.The analysis of heat tranfer shows that the cooling rate in its surface layer is about 104-105℃/sec which makes the layer self-quenched. In a specimen there are different heating temperatures and cooling rates in different layer depths with various mi-crostructures.The microstructure in resolidification zone is a skeleton of cementite with thick needle-like martensite and its microha-rdness HM(50g)is about 750.The microstructure in superheating zone is also a skeleton of cementite with thick needle-like martensite, but with additional large amount of residual austenite.The effect of the graphite is discussed in detail.The microstructure of the transformation hardened zone consists of granular cementite and tiny needle-like or concealed martensite and its microhardn-ess is about HM900. Heat affected zone is essentially a kind of high temperature tempering of the matrix.更多还原