Carbide Precipitation During Tempering of a Tool Steel Subjected to Deep Cryogenic Treatment
Carbide Precipitation During Tempering of a Tool Steel Subjected to Deep Cryogenic Treatment
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DOI：
10.1007/s11661-014-2202-8
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发表时间：
2014-05-01
影响因子：
2.8
通讯作者：
Kortmann, A.
中科院分区：
文献类型：
--
作者：
Gavriljuk, V. G.;Sirosh, V. A.;Kortmann, A.
采用透射电镜、穆斯堡尔光谱和硬度测量，研究了含（质量分数）1.55C、11.90Cr、0.70V和0.86Mo的X153CrMoV12钢在77 K或123 K（-196℃或-150℃）低温淬火和DCT深低温淬火三种处理后的回火过程中碳化物析出情况。与之前的一些研究相反，在低温下长时间保存后，没有检测到细小的碳化物析出。室温淬火后，在373 ~ 473 K（100 ~ 200℃）之间析出瞬态epsilon（epsilon’）碳化物，从573 K（300℃）开始转变为渗碳体。在123 K（-150℃）下的DCT，在373 K（200℃）回火后，只检测到细小的渗碳体颗粒，并且在更高的温度下延迟变粗。室温淬火后，在773 K（500℃）时析出渗碳体和合金元素碳化物，但也观察到一些未溶解的渗碳体板。在123 K（-150℃）DCT后，回火过程中未析出瞬态epsilon（epsilon’）碳化物，这是由于等温马氏体相变伴随塑性变形引起的。在这种情况下，渗碳体是在573 K至773 K（300℃至500℃）温度范围内析出的唯一碳化物相。如果在77 K（-196℃）下进行DCT，则在373 K至473 K（100℃至200℃）回火后发现epsilon（epsilon'）碳化物。粗渗碳体颗粒和合金元素碳化物的缺失构成了经受DCT和773 K（500℃）回火的钢的特征。结果表明，与室温淬火相比，二次硬度降低。根据Mossbauer研究，在773 K（500℃）下进行DCT和回火后的组织特征是α固溶体中残余奥氏体的数量减少，合金元素聚集。结果表明，磨损过程中残余奥氏体的应变诱导转变与碳化物析出之间的竞争控制了刀具的寿命。
Using transmission electron microscopy, Mossbauer spectroscopy, and measurements of hardness, the carbide precipitation during tempering of steel X153CrMoV12 containing (mass pct) 1.55C, 11.90Cr, 0.70V, and 0.86Mo is studied after three treatments: quenching at RT and deep cryogenic treatment, DCT, at 77 K or 123 K (-196 A degrees C or -150 A degrees C). In contrast to some previous studies, no fine carbide precipitation after long-time holding at cryogenic temperatures is detected. After quenching at room temperature, RT, the transient epsilon(epsilon') carbide is precipitated between 373 K and 473 K (100 A degrees C and 200 A degrees C) and transformed to cementite starting from 573 K (300 A degrees C). In case of DCT at 123 K (-150 A degrees C), only fine cementite particles are detected after tempering at 373 K (200 A degrees C) with their delayed coarsening at higher temperatures. Dissolution of cementite and precipitation of alloying element carbides proceed at 773 K (500 A degrees C) after quenching at RT, although some undissolved cementite plates can also be observed. After DCT at 123 K (-150 A degrees C), the transient epsilon(epsilon') carbide is not precipitated during tempering, which is attributed to the intensive isothermal martensitic transformation accompanied by plastic deformation. In this case, cementite is the only carbide phase precipitated in the temperature range of 573 K to 773 K (300 A degrees C to 500 A degrees C). If DCT is carried out at 77 K (-196 A degrees C), the epsilon(epsilon') carbide is found after tempering at 373 K to 473 K (100 A degrees C to 200 A degrees C). Coarse cementite particles and the absence of alloying element carbides constitute a feature of steel subjected to DCT and tempering at 773 K (500 A degrees C). As a result, a decreased secondary hardness is obtained in comparison with the steel quenched at RT. According to Mossbauer studies, the structure after DCT and tempering at 773 K (500 A degrees C) is characterized by the decreased fraction of the retained austenite and clustering of alloying elements in the alpha solid solution. It is suggested that a competition between the strain-induced transformation of the retained austenite and carbide precipitation during the wear can control the life of steel tools.