镶铸双金属复合锤头铸造工艺的研究

Research on Inlay Composite Casting Technology of Bi-metal Hammer

双金属复合锤头锤端复合层采用高铬铸铁,锤柄采用碳素结构钢。采用型内感应加热工艺进行镶铸复合。造型时锤柄预先放置在砂型中,锤端和浇注系统内浇道的成型采用消失模。复合时将包含有锤柄的砂型整体放入到感应圈内采用中频感应原理对锤柄进行预热,锤柄温度升高,锤端消失模受热汽化,锤柄达到预定温度后浇注并继续进行加热,复合层熔液将锤端部分锤柄包覆后停止加热并继续浇注,使金属液充满冒口。所得到的双金属复合锤头结合界面为完全冶金结合。经过热处理后,复合层组织为断续分布的Cr7C3 共晶碳化物+马氏体+少量残余奥氏体,硬度HRC≥58,冲击韧度≥12 J/cm2。基体组织为珠光体+铁素体。破碎石灰石和炼焦用原煤,镶铸双金属复合锤头使用寿命分别是高锰钢锤头的3倍和5倍左右。

The composite layer of bi-metal hammer is made up of high-chromium cast iron and base matrix material of hammer handle is ZG270-550. The combining technology is carried out by in-mold induction heating. The hammer handle with foam pattern of hammer-head is placed in the sand mold when molding. The sand mold with the hammer handle and foam pattern of hammer-head is wholly placed in the induction-heat ring. The hammer handle is preheated by the intermediate frequency induction heating. While its temperature is raising the foam pattern is gradually vaporized. The pour is begun when the temperature is reached and the heating is continued when pouring and stopped when the liquid metal wholly fill the mold. Pouring is continued until the cavity of riser is fully filled. The composite interface of bi-metal is wholly metallurgical bonding. The composite bed is Cr7C3 eutectic carbide + martensite + little residual austenite. HRC greater than or equal 58, impact ductility greater than or equal 12 J/cm2. Matrix is pearlite+ferrite. The service life of composite grinding roll is about 3 times over austenitic manganese steel.