共查询到20条相似文献,搜索用时 218 毫秒
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采用化学成分分析、扫描电镜和显微组织观察以及X射线能谱分析等方法,对42CrMo钢重型汽车前轴锻件淬火开裂的原因进行分析.结果表明,钢中残留的硼含量异常是造成工件淬火开裂的主要原因,同时原材料中的带状组织偏析和粗大的显微组织增加了淬火开裂的倾向. 相似文献
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研究了热加工温度和冷却方式连铸JW钢组织和力学性能的影响,结果表明不同温度加热,其冰冷组织的力这性能主要取决于铁素体和马氏体的相对体积分数及马氏体的形态。其空冷组织的力学性能主要取决于铁素体,粒状贝氏体和粒状组织的体积分数以及M-A岛的性态。偏析形成的条带状组织空冷后有马氏体转变。 相似文献
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薄板坯连铸连轧30CrMo钢的热轧组织与力学性能 总被引:2,自引:0,他引:2
利用光学显微镜、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉伸试验机和硬度仪分析了薄板坯连铸连轧生产的30CrMo钢的热轧微观组织和力学性能。结果表明,该钢主要由珠光体和铁素体组成,珠光体的表观片层间距在0.5μm以下,铁素体晶粒尺寸在5μm以下。该钢热轧屈服强度为461 MPa,抗拉强度达677 MPa,硬度为96.8 HRB,伸长率达23%。与传统厚板坯连铸工艺生产的30CrMo钢热轧组织比,CSP工艺生产的30CrMo钢的组织更细小,综合性能更优良。 相似文献
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低碳合金钢中带状组织的成因、危害和消除 总被引:43,自引:11,他引:32
研究了低碳合金钢中带状组织和混晶组织形成的原因、对钢材质量的影响和消除方法。结果表明,这两种组织主要是钢中的成分偏析引起的,而且常成因果关系。带状组织会降低钢的力学性能,切削加工性能和逆性成形性能,带状组织中的合金元素偏析,在常规退火、正火、淬火、渗碳加热条件下难以消除。采用电渣重熔、快速结晶、增大锻造比和扩散退火等技术,可以减轻或避免钢材带状组织的形成。 相似文献
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C.L. Mo Y. T. Zhang D.Z. Li Y. Y. Li 《金属学报(英文版)》2005,18(5):664-668
The microstructural banding in steels is often found in hot rolling strips, which plays a very important role in mechanical properties. Much work has been done to investigate how the microstructural banding is formed during hot rolling. In the present study, the microstructure of hot rolling strips was examined in term of optical microscopy and transmission electron microscopy. Electron probe microanalysis was also used to decide the distribution of microchemical bands, by this means, the phases in these strips were found to be ferrite and pearlite. The average distance between the carbon lamellas in pearlite is about 0.06-0.1μm. It is also shown that microstructural banding in hot rolled carbon steel was closely related to the segregation of manganese and silicon into those bands. Based on the transformation kinetic, the simulated results pointed out that the thermodynamic stability of austenite would increase with the increasing of Mn, which led to a decrease of ferrite growth rate. The effect of Mn on the decomposition of austenite is attributed to segregation of Mn atoms along the ferrite/austenite phase boundary which causes a strong solute drag effect. The addition of Mn to steel decreases the activity of austenite, thereby it is beneficial to the formation of non-equilibrium phase, such as degenerate pearlite. The formation of banded structure on the hot rolled process was discussed. 相似文献
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The segregation behavior of trace amount of phosphorus (P) and the mechanical properties of dual-phase (DP) steels have been systematically studied. The microstructure of DP steels is mainly composed of martensite, ferrite and nanoscale carbides. For the DP steels with different trace amounts of P (≤ 0.015 wt%), P has almost no effect on the mechanical properties. Atom probe technology (APT) analyses confirm that P segregation was only found at the precipitate/matrix interface. Moreover, the precipitates of (Ti, Mo) C are widely distributed in the ferrite, martensite and ferrite/martensite interface regions. The special segregation feature of P would not concentrate at specific regions such as ferrite/martensite interface and/or martensite lath interface, which reveals that trace amounts of P (≤ 0.015wt%) have almost no effect on the mechanical properties of DP steels. It is proved for the first time that the MC-type carbides of (Ti, Mo) C can reduce or eliminate the damage effect of P on the mechanical properties of steels, which provides a new way for the design of alloys to reduce P damage. This work will promote to increase the P content control standard in DP steels from 0.01 to 0.015 wt%, which will not change the mechanical properties, but greatly reduce the scrap rate and increase the energy efficiency of the manufacturing process. 相似文献
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通过采用化学分析、组织观察和力学检验等手段对Q345T钢板桩初检与复检力学性能检验结果差别较大的原因进行了分析。结果表明,组织中带状组织、魏氏体组织,以及带状的夹杂物是导致钢材强度低的主要原因。追溯钢材的整个生产过程可知,钢水冶炼时除杂除气不充分、板坯浇铸后期杂质聚集偏析、加热温度控制不均匀是造成钢材组织与性能不合格的根本原因。 相似文献
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对18CrNiMo7-6齿轮钢进行了温锻余热等温正火工艺研究。结果表明:在温锻余热等温正火工艺中,冷却速度、等温温度、等温时间为关键的工艺参数。较低冷却速度和较高的等温温度,可在有限等温时间内有效提高珠光体的转变量,减少残留奥氏体含量及室温马氏体和贝氏体等非平衡组织,获得理想的组织及性能。以0.1 ℃/s和1 ℃/s冷却速度降至等温正火温度650 ℃保温1 h 后冷却可获得硬度163~164 HBS,F晶粒度10~11.5级,带状组织1.5级,组织及性能均符合技术要求,可具有良好的切削加工性能,并为后续热处理工艺提供理想组织。 相似文献
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研究了回火温度对大尺寸锻态35CrMo钢调质处理后组织特性及力学性能的影响,特别针对回火过程中渗碳体的析出动力学及大尺寸试块的组织性能不均匀性展开了分析。结果表明,锻坯热处理前的铁素体、珠光体带状组织经调质处理后完全消除,最终组织为含有大量渗碳体析出的回火马氏体,同时试块心部包含少量分布于原奥氏体晶界的回火贝氏体。回火过程中渗碳体的析出分为C扩散控制的快速长大阶段和Cr扩散控制的尺寸稳定阶段。锻态35CrMo钢经调质处理后仍存在力学性能各向异性,随着回火温度的升高,试验钢横、纵向强度下降,塑性和韧性同步提升。经综合考虑,当回火温度为570 ℃时,其强度、塑性和韧性具有最优匹配。 相似文献
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利用光学显微镜、扫描电镜和冲击试验机等仪器研究了15CrMoR钢中带状组织在热处理过程中的演变及其对冲击性能的影响。结果表明:奥氏体化后缓冷会出现铁素体-珠光体带状组织, 快冷则可以抑制带状组织的出现,但快冷会导致粒状贝氏体等非平衡组织形成。粒状贝氏体组织中的贝氏体铁素体基体和马氏体-奥氏体岛在回火过程中逐渐沿Cr、Mo等碳化物形成元素偏聚的区域分解出碳化物,形成富碳化物带,降低钢的横向冲击性能。15CrMoR钢加热到1100 ℃并保温7 h后可消除带状组织,改善钢的横向冲击性能。 相似文献