离心球墨铸铁管的组织及退火工艺研究

Microstructure and Mechanical Properties of Large Diameter Centrifugal Casting Ductile Iron Pipe and Its Annealing Process

从大型离心球墨铸铁管上取样 ,用光学金相、电子金相法研究了铸造和不同退火状态下的离心球墨铸铁的组织 ,实行了低温退火新工艺。研究表明 ,采用低温退火 ,使片状珠光体转变为粒状珠光体 ,并且控制粒状珠光体量为 15 %～ 2 5 % ,其余为铁素体 +石墨 。

Microstructure of centrifugal casting ductile iron and its microstructure after different annealing processes were investigated by means of electronic metallography.All samples were from large diameter centrifugal casting ductile iron pipes.A new low temperature annealing process was carried out.As result is showing,lamelar pearlite is transforming granular pearlite after a low temperature annealing,the quantity of granular pearlite is being confined of 15 percent to 25 percent,the other is ferrite and graphite.This kind of microstructure is revealing good comprehensive mechanical properties.