【摘要】：利用選區(qū)激光熔化(SLM)增材制造技術(shù)成功制備了5Cr Ni4Mo模具鋼試件,研究了激光成形5Cr Ni4Mo模具鋼的相變過程及其機(jī)制,分析了激光線能量密度η(激光功率與掃描速度之比)對SLM成形件致密度、顯微組織和力學(xué)性能的影響規(guī)律。研究表明:過高的η(387.5 J/m)引起球化效應(yīng),使得成形件內(nèi)部含有殘留孔隙,成形致密度降低;過低的η(155.0 J/m)導(dǎo)致熔體潤濕性較低,成形致密度較差。將η優(yōu)化為258.3 J/m時(shí),成形試件加工缺陷減少,成形致密度提升到98.12%。激光加工的快速冷卻作用易導(dǎo)致馬氏體相變;原始粉末中的Mn、Ni、Cr等合金元素可以增加過冷奧氏體的穩(wěn)定性,降低馬氏體臨界冷卻速度,從而確保了馬氏體轉(zhuǎn)變的順利進(jìn)行;隨著η的降低,馬氏體組織發(fā)生明顯的細(xì)化。當(dāng)η=193.8 J/m,成形試件具有較高的顯微硬度(689.5 HV0.2)、較低的摩擦系數(shù)(0.44)和磨損率[2.3×10~(-5)mm~3/(N·m)]。
[Abstract]:5Cr Ni4Mo die steel specimens were successfully prepared by selective laser melting (SLM) technology. The transformation process and mechanism of laser forming 5Cr Ni4Mo die steel were studied. The effect of laser linear energy density 畏 (the ratio of laser power to scanning speed) on the density, microstructure and mechanical properties of SLM forming parts was analyzed. The results show that the spheroidizing effect is caused by too high 畏 (387.5 J 鈮，

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