碳素鋼車軸金相組織對超聲波透聲性能的影響

碳素鋼車軸金相組織對超聲波透聲性能的影響Effect of Metallographic Structure of the Carbon Steel Axle on Its Ultrasonic Transmission Performance

針對LZ50和C35e車軸的超聲檢測時軸向超聲波透聲不良的問題，對采用相同生產(chǎn)工藝且晶粒度級別基本相同的相應(yīng)規(guī)格的車軸進(jìn)行解剖分析。結(jié)果表明：超聲波透聲性能不良車軸的金相組織存在區(qū)域性珠光體聚集，或存在珠光體、鐵素體群的區(qū)域性分布，局部伴有類似針狀的鐵素體；而超聲波透聲性能合格車軸的金相組織呈均勻的“珠光體+鐵素體”細(xì)晶粒組織。實踐表明，這種珠光體聚集或珠光體、鐵素體群的區(qū)域性分布會使軸向超聲波散射衰減增大，而且這種組織比局部單個大晶粒對軸向超聲波散射衰減的影響更大。實際生產(chǎn)中，應(yīng)對鋼坯冶煉、軋制及車軸鍛造和熱處理過程進(jìn)行有效地控制，才能消除或削弱這種組織的存在。

With regard to the poor axial ultrasonic transmission of the LZ50 and C35e axles, the axles of the corresponding specification varieties with the same process and the same grain sizes were anatomically analyzed. The results show that the regional pearlite aggregation or regional distribution of pearlite and ferrite group (locally accompanied by needle-like ferrite) exist in the metallographic structure of poor axial ultrasonic transmission axles. On the other hand, a uniformly distributed pearlite and ferrite fine grain structure exists in the metallographic structure of axles with qualified ultrasonic transmission. Practice shows that the pearlite aggregation or the regional distribution of pearlite, ferrite group will make the axial ultrasonic scattering attenuation increase, and the influence of such microstructure on axial ultrasonic scattering attenuation is greater than locally single great grain. In practice, billet smelting, rolling and axle forging and heat treatment should be effectively controlled to eliminate or weaken the existence of this kind of structure.

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