共查询到18条相似文献,搜索用时 62 毫秒
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对20CrNi3Mn2Al 时效硬化钢进行不同温度和不同时间的离子渗氮处理,优选出最佳渗氮工艺为520~540 ℃×50 h氨气变温深层离子渗氮处理,表层硬度高,化合物层薄,硬度梯度好,表面下0.1 mm处硬度大于900 HV,0.4 mm处硬度大于600 HV,渗氮层深大于0.7 mm,基体硬度为400~450 HV,可用于制造大型重载高速精密齿轮,部分替代渗碳钢,省去渗碳和油淬工序,简化工艺,减少变形。 相似文献
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研究了20Cr3MnMoV钢热处理工艺参数对力学性能和渗氮硬化性能的影响。结果表明:20Cr3MnMoV钢热处理由固溶处理、时效、预时效和渗氮组成。合理控制时效过程是20Cr3MnMoV钢热处理的主要工艺特点。分别采用固溶处理后充分时效,无预时效直接渗氮和先预时效再渗氮等多种工艺,可以适应于不同工作条件的模具和构件,以满足耐磨性和强韧性的不同要求。20Cr3MnMoV钢氮碳共渗处理,可实现快速渗氮,深层渗氮硬化和基体强化,有广泛应用前景。 相似文献
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以马氏体时效钢为研究对象,将试验钢经900 ℃固溶后,再进行500 ℃等温时效处理,采用光学显微镜、扫描电镜及维氏硬度计表征了时效过程中其显微组织与析出相及硬度变化规律,在此基础上,分析了时效工艺对马氏体时效钢显微硬度变化的影响。结果表明,在时效初期,试验钢硬度增幅明显,并于12 h时达到峰值,为585 HV30。随着时效时间进一步延长,试验钢进入过时效状态,硬度开始缓慢下降。试验钢基体由板条马氏体与残留奥氏体组成,且基体分布着细小弥散的第二相颗粒。时效0.5 h时,析出相尺寸为5~10 nm,当时效达到12 h时,析出相缓慢长大至20~25 nm。 相似文献
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时效工艺对新型不锈钢零件尺寸稳定性的影响 总被引:2,自引:0,他引:2
对15-5PH不锈钢制零件进行时效处理,找到时效工艺对尺寸稳定性、硬度的影响规律,为制定合理的机加工艺路线提供依据. 相似文献
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研究了400℃至800℃再加热处理后超低碳铜时效强化钢组织和性能的变化.利用光学显微镜、扫描电镜、透射电镜观察和X射线衍射分析了不同温度再加热处理后钢显微组织和ε-Cu沉淀的特征.结果表明,再加热温度不高于650℃的条件下,钢的强度和韧性未明显下降,即具有优良的热稳定性;再加热温度高于650℃则钢的屈服强度明显降低,这是由于基体组织发生明显的回复以及ε-Cu沉淀粗化;再加热温度高于700℃钢的韧性明显降低,这是大量高硬度M/A岛组织出现所造成.分析表明基体组织的回复,ε-Cu沉淀的数量和尺寸及M/A岛组织是影响超低碳铜时效强化钢热稳定性的主要因素. 相似文献
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高性能铜沉淀硬化船体钢 总被引:4,自引:0,他引:4
通过大幅度降低钢中碳含量,利用铜的时效析出强化作用以及铌的微合金化作用,在碳含量小于0.06%(质量分数)时,获得了屈服强度高于600 MPa、-40℃时冲击功超过250 J、可实现0℃不预热焊接的高性能新型船体结构钢.实验表明:在钢体中加入1%(质量分数)的铜可使其屈服强度增大270~350 MPa.该钢的应用可望大幅降低大型船体的建造成本,代表了新一代船体钢的发展方向. 相似文献
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V.H. Baggio-Scheid A.J. Abdalla G. de Vasconcelos 《Surface & coatings technology》2006,201(7):4058-4061
Although plasma nitriding has been applied successfully to increase the hardness of austenitic stainless steels, the process cycles are long due to the low nitrogen diffusion rate for these steels. An alternative to reduce the nitriding time is to perform a heating treatment after nitriding to prolong the diffusion process. In this work we investigate the properties of plasma nitrided AISI 316 stainless steel after heating post-treatments. The samples were nitrided at 823 K during 3 h. After nitriding, heating post-treatments were performed in a vacuum furnace. The influence of the heating time, ranging from 1 up to 16 h, and heating temperatures, varying from 732 up to 873 K, on the surface properties was investigated. The samples were characterized using microhardness testing, scanning electron microscopy and X-ray diffraction. The nitriding treatment results in a compound layer 44 μm thick with a hardness of 1434 HV0.1, consisting predominantly of γ'-[Fe4N] and CrN phases. As expected, an increase of the compound layer thickness and a decrease of the surface hardness with heating time were observed. However, the microhardness profiles show that beneath the surface the layer hardness increases for long treatment times. New phases as Fe3O4 and FeCr2O4 appear and grow with increasing heating time. 相似文献
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I. Calliari M. Dabalà E. Ramous M. Zanesco E. Gianotti 《Journal of Materials Engineering and Performance》2006,15(6):693-698
In this study the effects of a surface-controlled decarburization on the structure of a nitrided steel are analyzed. Samples
of a quenched and tempered 42CrMo4 steel were decarburized by heating in air at different depths and submitted to gaseous
nitriding. After decarburization and nitriding, the microstructure of surface layers was investigated by optical microscopy
(OM) and scanning electron microscopy (SEM). The nitrogen and carbon profiles in the diffusion layers were determined by SEM
equipped with a wavelength dispersive spectrometer (EPMA-WDS) and by glow discharge optical spectrometry (GDOS). The effect
of nitriding was determined by microhardness measurements. Our results indicate that a previous decarburization only slightly
affects the surface hardness, but reduces the conventional nitriding depth. The decarburization also favors the nitrogen take-up
and produces increased nitrogen concentrations in the compound layer and in the narrow zone beneath it. 相似文献
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在不同温度下对碳钢Q235和42CrMo钢进行气体渗氮,利用光学显微镜、扫描电镜、能谱仪及X射线衍射仪对比分析了Q235和42CrMo钢渗氮层的微观组织及相结构,并用电化学方法测试了样品的耐腐蚀性。经过渗氮处理后的样品的耐腐蚀性都较原材有大幅提高,而相同温度渗氮后42CrMo钢的自腐蚀电位较Q235钢的低,42CrMo钢渗氮层电阻小于Q235钢,碳钢渗氮层的耐蚀性优于合金钢。采用热力学和第一性原理计算探讨了42CrMo钢的合金元素对渗氮层的抗腐蚀性的影响。结果表明合金元素Cr、Mo通过降低Fe-N化合物稳定性从而降低渗氮层的抗腐蚀性。 相似文献