NOTCH WEAR OF MACHINING NICKEL BASED ALLOYS WITH CERAMIC TOOLS

ＮＯＴＣＨＷＥＡＲＯＦＭＡＣＨＩＮＩＮＧＮＩＣＫＥＬＢＡＳＥＤＡＬＬＯＹＳＷＩＴＨＣＥＲＡＭＩＣＴＯＯＬＳＮＯＴＣＨＷＥＡＲＯＦＭＡＣＨＩＮＩＮＧＮＩＣＫＥＬＢＡＳＥＤＡＬＬＯＹＳＷＩＴＨＣＥＲＡＭＩＣＴＯＯＬＳＨｅＮｉｎｇ；ＰａｎＬｉａｎｇｘｉａｎ...     

STUDY ON WEAR AND DESTRUCTION OF HOB IN GEAR HOBBING

The wear and destruction appearances of hobs are researched. The reasons of the wear and destruction of hobare analyzed. And the influence of the change of the bobbing force and the bobbing temperature on the wear and destruction of hob in gear bobbing is also analyzed. In gear bobbing, the main wear mechanisms are adhesion and ploughingwhen cutting the 20CrMnTi gear using W18Cr4V high-speed steel hob.     

DISTRIBUTION OF Cu AND ITS EFFECT ON MICROSTRUCTURE OF Cu-BEARING STEEL

In order to investigate the distribution of Cu and its effect on the microstructure of Cu-bearing steel, a series of mild steels containing different contents of Cu are developed by vacuum electric arc furnace. These steels are annealed at 1 260℃, 1 100℃and 1 000℃respectively for one hour and followed by furnace cooling to room temperature to simulate the heat treatment before the rolling process. The results show that Cu did not obviously segregate in annealed steels. The scanning electron microscope (SEM) observation show that the main microstructures in Cu-bearing steel are ferrite and pearlite; The volume fraction of pearlite in steel increase with increasing Cu content. The grain size reduces with the decrease of annealing temperature. The results of energy dispersive X-ray analysis (EDXA) suggest that the Cu content in pearlite is higher than that in ferrite, which means that the microstructure-segregation of Cu exists. However, the cast specimens show that Cu content in MnS and S-rich phase is very high, and Cu changed the distribution of MnS in steel. In addition, the optimal Cu content in steel between 0.2%-0.4% and the optimal annealing temperature between 1 100-1 200℃are determined by the economical and practical principles.     

PCBN刀具切削GCr15淬硬轴承钢的研究

通过切削实验,研究了PCBN刀具精密切削淬硬GCr15轴承钢时切削力的特征、锯齿切屑的形态和刀具的员特征,又从表面粗糙度、硬化层深度、亚表层的白层现象和残余应力的分布方面深入研究了PCBN刀具精密切削淬硬轴承钢的适应性,实验结果表明,PCBN刀具应用于GCr15轴承钢的精密切削是可行的。     

用PCBN刀具精密切削GCr15淬硬轴承钢

通过切削试验研究了PCBN刀具精密切削GCr15淬硬轴承钢时的切削力特征、切屑形态、刀具磨损特性等切削性能 ,并从表面粗糙度、硬化层深度、亚表层白层现象、残余应力分布等方面研究了PCBN刀具精密切削淬硬轴承钢的加工表面质量     

PCBN刀具和硬质合金刀具铣削GCr15的对比试验研究

在干式切削的条件下,采用单因素试验法,比较分析了PCBN刀具和硬质合金刀具铣削轴承钢GCr15的差异。结果表明:PCBN刀具在铣削过程中不产生积屑瘤,可获得更好的表面粗糙度,后刀面的磨损较小。     

PCBN刀具切削淬硬钢GCr15的磨损实验研究

以PCBN刀具切削淬硬轴承钢GCr15为实验对象，对干湿切削条件下的刀具磨损形式、磨损原因及刀具寿命进行了对比实验研究。实验结果表明：干湿切削磨损形式相似，但干切削时前刀面磨损面积较大；磨损机理主要为摩擦磨损、粘结剂磨损、扩散磨损和氧化磨损；湿切削比干切削的正常磨损时间稍长一些。     

STUDY ON STRUCTURE AND PROPERTIES OF 18Si MnCu DUAL PHASE STEEL

ＳＴＵＤＹＯＮＳＴＲＵＣＴＵＲＥＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦ１８ＳｉＭｎＣｕＤＵＡＬＰＨＡＳＥＳＴＥＥＬ￥ＹｕＳｈｅｎｊｕｎ；ＧｏｎｇＦａｎｇｙｕｅ；ＬｉＳｈａｎｙｏｕ；ＷａｎｇＣｈｕｎｙａｎ；ＣｈｅｎＹｕｒｕ；ＣｈｅｎＦｕｍｉｎ（ＴｉａｎｊｉｎＵ...     

PCBN刀具切削GCr15淬硬轴承钢时刀具磨损的研究

通过切削实验，研究了PCBN刀具切削淬硬轴承钢时刀具磨损形态及磨损机理。实验表明。PCBN刀具前刀面的磨损为月牙洼磨授，后刀面的磨损为机械磨损，其磨损程度与工件硬度呈非线性关系，并随着切削速度的提高磨损量减少。     

MECHANICAL PROPERTIES AND ANTIWEARABILITY STUDIES OF MULTILAYER THIN COATINGS ON CUTTING TOOLS

The nanoindentation fracture of multilayer hard coatings, such as TiN, TiN/Ti(C,N)/TiC, TiN/Ti(C,N)/TiC/Ti(C,N)/TiC and TiN/Ti(C,N)/TiC/Ti(C,N)/TiC/Ti(C,N)/TiC coatings, deposited on cemented carbide using a CVD technique are studied. It is found that these coatings have high hardness. Based on the analysis of the energy release in cracking, the fracture toughness of these coatings are calculated. The observations clearly establish a step occurs in the forcedisplacement curves at the onset of coating fracture and a straigh t line segment in the loadpenetration depth squared curves to identify the interfacial failure of coatings. The hardness, fracture toughness and antiwearability of these coatings are clearly compared. The results show that with the layes increasing, the fracture toughness and antiwearability are getting larger.     

PCBN刀具干切削淬硬轴承钢时磨损机理的研究

通过干切削淬硬GCr15轴承钢的PCBN刀具磨损试验 ,得出了后刀面刀具磨损曲线 ,结合扫描电镜对刀具的磨损形态进行了宏观和微观观察 ,研究了PCBN刀具的磨损特征及磨损机理 ,并对切屑形态与刀具磨损之间的关系进行了初步探讨     

GCr15钢超高周疲劳行为的实验研究

以GCr15钢为实验材料进行旋转弯曲超高周疲劳行为的实验研究.用光学显微镜和扫描电镜对试样疲劳断口进行观察,结果显示,疲劳断裂周次从106直到4×108,GCr15钢疲劳裂纹大多起源于试样内部,裂纹源一般为非金属夹杂物.从内部起裂的试样,疲劳寿命一般比从表面起裂试样的寿命长.文中从断裂力学和断裂物理的角度,对实验结果和疲劳机理进行分析.     

PCBN刀具的磨损机理和干切削GCr15时的磨损与寿命

研究了PCBN刀具的磨损机理和磨损形式。通过对干切削GCr15轴承钢时刀具的磨损形式及寿命进行试验研究 ,得出了工件硬度、切削速度对PCBN刀具磨损的影响规律以及工件硬度在临界硬度附近时刀具磨损速度最快的结论。加工两种硬度工件时的刀具寿命方程表明 ,切削速度对PCBN刀具寿命的影响小于对硬质合金及陶瓷刀具寿命的影响。     

研磨加工层对高碳铬轴承钢超长寿命疲劳行为的影响

为了阐明磨石研磨加工层对高碳铬轴承钢JIS SUJ2超长寿命疲劳行为的影响,分别使用经砂纸研磨和电解研磨的砂漏形试样,在室温空气环境下进行旋转弯曲疲劳试验.砂纸研磨试样被除去部分磨石研磨层,电解研磨试样被除去了全部的磨石研磨层.结果表明,两种试样的S-N曲线由位于短寿命区的表面破坏模式和位于长寿命区的内部破坏模式的两条组成,表面破坏模式的S-N曲线受表面粗糙度和表面压缩残余应力的影响.内部破坏模式的S-N曲线不受表面条件的影响,是材料固有的特性.砂纸研磨试样表面破坏模式的疲劳极限最高,是电解研磨试样1.11倍和磨石研磨的1.20倍.表面压缩残余应力对表面破坏模式疲劳极限的影响可以用修正Goodman图表示.还讨论裂纹的萌生和扩展条件,推定超长寿命的疲劳极限.     

GCr15钢不同回火态扭转流变硬化行为和组织强度研究

研究了ＧＣｒ１５钢淬火不同温度回火后扭转流变硬化行为、组织和强度的关系。研究表明，在双对数坐标上硬化曲线呈现多ｎ行为。在低于２５０℃回火，随回火温度降低，诸ｎ值增大的原因很多，但残余奥氏体及其塑变诱导相变强化效应在其中起着主要作用。在高温回火范围，随回火温度降低，诸ｎ值减小的原因与渗碳体质点间距，即位错运动平均自由程（ＭＦＰ）有关。尽管宏观扭转断口有正断和切断之分，但微观断口均为韧窝，这表明塑变和硬化在断裂过程中起着重要作用。据此，可借助τ（０．３）、γｋ和ｎｌ值的变化分析τｋ值随回火温度变化的规律。