金属型离心铸造Ti—48%Al—2%Cr—2%Nb合金汽车排气阀的研制

本文利用离心铸造的方法，在金属型中浇铸了T 湛8%A轼%Cr-2%Nb合金汽车排气阀，通过SEM、XRD和EMPA等分析手段。对排气阀坯件的表面层结组织形态、成分分布和力学性能等特征进行了检测，并将热等静压（HIP）处理后的排气阀安装到483Q型柴油发动机上进行了台架试验，结果表明，金属型离心浇铸Ti-Al基合金排气阀，在保证阀体成分均匀性的同时，可在一定程度上细化铸件的显微组织，HIP处理后排气阀的平均力学性能为：σb=670MPa,σ0.2=527.5MPa和δ=3%，进一步的台架测试结果表明，热电厂气阀在测试过程中表现出了优异的密封性和耐磨性，完全满足发动机的性能要求。

Research onTi-48%Al-2%Cr-2%Nb Automobile Exhaust Valve Cast by Centrifugal Casting Process inPermanent Mold

In this paper, Ti-48Al-2Cr-2Nb automobile exhaust valve was castby the centrifugal casting method in permanent mold and its surface layer structure, microstructure, element distribution , mechanical properties etc were analyzed by SEM, XRD and EMPA . Furthermore, the valves treated by HIP were tested on 483Q diesel engine platform. Results showed that the distribution of alloying elements in Ti-Al based alloy for exhaust valve was uniform and its microstructure was refined to a certain extent. The mechanical properties of exhaust valve cast by centrifugal permanent mold then treated by HIP were that the σb = 670MPa, σ0.2 =527.5MPa and δ=3%. Result of the engine platform test showed that the valve had excellent air-tightness and wear-resistant properties, so could successfully satisfy requirements of the engine.