Effect of deep cryogenic treatment on the properties of 80CrMo12 5 tool steel

The effect of deep cryogenic treatment on the mechanical properties of 80CrMol2 5 tool steel was investigated.Moreover,the effects of stabilization (holding at room temperature for some periods before deep cryogenic treatment) and tempering before deep cryogenic treatment were studied.The results show that deep cryogenic treatment can eliminate the retained austenite,making a better carbide distribution and a higher carbide amount.As a result,a remarkable improvement in wear resistance of cryogenically treated specimens is observed.Moreover,the ultimate tensile strength increases,and the toughness of the sample decreases.It is also found that both stabilization and tempering before deep cryogenic treatment decrease the wear resistance,hardness,and carbides homogeneity compared to the deep cryogenically treated samples.It is concluded that deep cryogenic treatment should be performed without any delay on samples after quenching to reach the highest wear resistance and hardness.     

Microstructural evolution of a heat-treated H23 tool steel

The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures (...     

热处理工艺对低合金耐磨钢组织和性能的影响

通过对低合金耐磨钢热处理工艺试验．研究了不同淬火和回火温度对材料组织和性能的影响．结果表明：经过920℃／30min水淬＋260℃／2h回火处理后,试样晶粒细小,组织为板条马氏体、碳化物和少量残余奥氏体,并具有最佳的冲击韧性和硬度．     

碳化物对H13钢退火软化的作用

利用电子衍射,分析了Ｈ１３钢退火组织中的碳化物类型,并指出,由于它们溶入奥氏体的强工不同,聚集强度和显微硬度各异,使得碳化物能够长大,并削弱硬度较高的碳化物的硬化作用。     

磨损条件对冷作模具钢的磨粒磨损特性及机理的影响

本文通过对三种冷作模具钢LDI、65Nb和Cr12MoV在不同磨损条件下的磨粒磨损试验,并结合金相组织分析和SEM形貌观察,研究了试验钢的磨粒磨损特性,讨论了钢的组织和力学性能对耐磨性的影响。结果表明:材料的磨损机理随磨损条件的变化而变化;LDI钢540℃两次回火组织具有优良的耐磨性。     

Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.     

深冷处理对双金属带锯条切削性能的影响

应用实验手段研究了深冷处理对双金属机用带锯条切削性能的影响，包括对刃部材料M42钢的红硬性、耐磨性的研究以及对背部材料Rm80钢疲劳性能的分析。结果表明：深冷处理不仅可提高M42钢的红硬性、耐磨性；同时提高了Rm80钢的抗疲劳性能，延长刀具的使用寿命，通过对比回火前和回火后 深冷处理工艺，发现采用回火后 深冷处理工艺能显著提高材料寿命。     

The hydro-abrasive erosion wear behavior of duplex-treated surfaces of AISI H13 tool steel

The influence of duplex surface treatments consisting of a DC-pulsed plasma nitriding process and subsequent coatings of CrN and TiAlN deposited by physical vapor deposition(PVD)on AISI H13 tool steel was studied in this article.The treated samples were characterized using metallographic techniques,SEM,EDS,and microhardness methods.Hydro-abrasive erosion wear tests were performed in a specifically designed wear tester in which the samples were rotated in a wear tank containing a mixture of distilled water and ceramic abrasive chips with a fixed rotational speed.The wear rates caused by the abrasive particle impacts were assessed based on accumulated weight loss measurements.The worn surfaces were also characterized using optical microscopy,SEM,and EDS.Microhardness measurements indicated a significant increase in the surface hardness of the duplex-treated samples.The surfaces of the samples with the TiAlN coating were approximately 15 times harder than that of the untreated samples and 3 times that of the plasma nitrided samples.Hydro-abrasive erosion wear results showed that the duplex surface treatments,especially the CrN coating,displayed the highest erosion wear resistance.     

Electrochemical corrosion behavior of the laser continuous heat treatment welded joints of 2205 duplex stainless steel

The electrochemical corrosion behaviors of the welded joints of 2205 duplex stainless steel with the laser continuous heat treatment were investigated. The secondary austenite formation is the outcome of thermodynamic equilibrium breach of the alloy during heat treatment and the result of the continuous heat treatment which has the most important effect on the weld material. The partitioning behaviors of chromium and molybdenum as well as the volume fraction of ferrite and austenite have a remarkable influence on the composition of the individual phase. Mechanical examination of the laser trated weld demonstrates that the tensile strength and yield strength increase with increasing the amount of the secondary austenite. It is shown that the ultimate tensile strength of the 6 kW laser-treated weld is higher about 20 MPa than no heat treatment weld and the ductility can be further improved without compromising strength. The results indicate that the welding alters the corrosion behavior because of different post heat treatment power and the broad active peak is not identified which is attributed to the dissolution of the secondary austenitic in the ferrite phase. It is indicated that pitting resistance equivalent (PRE) values of base metal and 6 kW weld are higher than that of other welds; base metal is 33.7, 6 kW weld 33.3, no treatment 32.4, 4 kW weld 32.8, 8 kW weld 32.5. The extent of corrosion resistance improvement after reheating treatment is mainly caused by the removal of nitrogen from ferritic regions, which occurred as a consequence of secondary austenite growth.     

深冷处理对W4Mo3Cr4VSi钻头耐磨性的影响

刀具深冷处理可以以较低成本改善贵重工模具材料的显微组织,提高其机械性能．本文结合具体的高速钢刀具材料进行了深冷处理试验,并对其做了大量的对比分析,研究了高速钢钻头显微组织及耐磨性的变化．结果表明,深冷处理可以改变高速钢钻头的显微组织结构,提高刀具的硬度,增强刀具的耐磨损性能．     

Implementation of remote monitoring system for prediction of tool wear and failure using ART2

Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via internet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.     

热处理对S7钢组织和硬度的影响

研究了热处理工艺对S7钢组织和硬度的影响,结果表明,S7钢在810－830℃加热,15－30℃/h冷却,软经效果最好,在850－880℃加热淬火,550℃回火,可满足热作模具钢的使用性能要求。     

热处理对Cr26型高铬铸铁组织与性能的影响

研究Cr26型高铬铸铁经过不同的热处理后,其组织、硬度和耐磨性之间的关系。实验结果表明,最佳的淬火工艺是1 050℃×60 min后空冷,硬度为64.2 HRC;材料的硬度越高耐磨性能越好;并从组织状态和磨损机理方面分析了其原因。     

热处理对TRIP590钢微观组织及力学性能的影响

采用Gleeble3800热模拟机对TRIP钢拉伸试样进行不同工艺条件的快速热处理模拟实验,并采用金相分析、显微硬度测试等方法对试样进行组织观察和性能测试,目的是通过适宜的热处理工艺促使材料微观组织中出现适量的残余奥氏体组织,增强该材料在变形过程的相变诱导塑性（TRIP）效应,强化材料.结果表明：在两相区内,TRIP钢中的残余奥氏体含量随着退火温度和退火时间的增加而增大,以25℃/s缓慢加热到700℃,再以150℃/s的速率快速加热到820℃保温120 s后淬火处理,处理后的试样,残余奥氏体体积分数达到13%,显微硬度最高,达到262 HV.     

高碳低合金钢低温贝氏体组织及其耐磨性研究

设计了一种新的低温等温转变无碳化物贝氏体高碳低合金钢。对该钢低温等温淬火组织和干滑动摩擦磨损耐磨性及磨损机理进行研究,并与淬火＋低温回火处理试样进行比较。结果表明,经1 000℃奥氏体化后在220℃盐浴中进行等温120 h的等温淬火处理,得到了由平均厚度约为120 nm的板条状贝氏体铁素体和薄膜状的残留奥氏体组成的无碳化物贝氏体组织,干滑动摩擦磨损相对耐磨性比回火马氏体组织提高19%,磨损机理为粘着磨损。     

矿浆流变特征对钢球磨损规律的影响

探讨了湿式磨矿过程中矿浆流变特性对钢球磨损的影响规律,研究结果表明,矿浆粘度随矿浆体积分数的增大而增大,当矿浆体积分数大于50％时,矿浆粘度急剧增大,矿浆粘度是影响钢球磨损率的主要流变学因素,当矿浆粘度介于500－1000mPa.s时,钢球的磨损率出现最大值,当矿浆体积分数较高时,添加化学助剂NaNO2,钢球的磨损率降低,磨矿效率提高,控制磨矿条件能改善矿浆的流变学特性,使钢球表现的罩盖层厚度处于最佳值,从而提高磨矿效率,降低钢球的磨损率。     

全钢载重子午线轮胎胎面磨耗行为研究

以12R22.5全钢载重子午线轮胎为研究对象,建立含纵向花纹的轮胎有限元模型,采用磨耗后处理法模拟胎面磨耗行为. 将制动条件下计算得到的沟深磨耗量与道路实测结果进行对比,两者相对误差为10.2%,验证了该处理方法的可靠性. 对4种不同行驶工况的轮胎胎面进行磨耗仿真分析. 结果表明,自由滚动工况磨耗主要发生在花纹沟边,制动工况胎肩部花纹块磨耗深度较大,驱动工况磨耗主要发生在胎中部花纹块,侧偏工况胎面橡胶磨耗速率最快. 考察充气压力和载荷对胎面磨耗的影响. 结果表明,载荷增大、充气压力减小使胎面磨耗的不均匀性增加. 对于超压超载工况,仿真得出自由滚动5×10⁴ km后胎面橡胶磨耗质量是额定工况的1.56倍.     

马氏体不锈钢等离子堆焊铁基合金组织及磨损性能

为了研究马氏体不锈钢的表面性能,采用等离子堆焊技术在Z5CND16-04不锈钢表面制备铁基合金堆焊层.采用扫描电子显微镜、能谱仪、X射线衍射仪、显微硬度计及销盘磨损实验机等检测设备,对堆焊层的组织结构、成分、硬度和磨损性能进行了研究.结果表明,铁基合金堆焊层主要由α-Fe、(Fe,Cr,Mo)7C3和(Fe,Cr,Mo)23C6相组成,添加稀土元素后相组成无明显变化.铁基合金堆焊层的硬度和耐磨性均明显高于马氏体不锈钢基材.添加适量的CeO2后,明显细化了堆焊层的显微组织.     

Characterization and wear behavior of WC-0.8Co coating on cast steel rolls by electro-spark deposition

To prepare high wear resistance and high hardness coatings, electro-spark deposition was adopted for depositing an elec trode of a mixture of 92wt%WC+8wt%Co on a cast steel roll substrate. The coating was characterized by classical X-ray diffracto meter (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The results indicate that the coating shows nanosized particulate structure and dendritic structure including columnar structure and equiaxed structure. The pri mary phases of the coating contain Fe_3W_3C, Co_3W_3C, Fe_2C and Si_2W. The coating has a low friction coefficient of 0.13, its average wear-resistance is 3.3 times that of the cast steel roll substrate and the main mechanism is abrasive wear. The maximum microhard ness value of the coating is about 1573.9 Hv_(0.3) The study reveals that the electro-spark deposition process has the characteristic of better coating quality and the coating has higher wear resistance and hardness.     

夹杂物对Cr13铸钢耐磨性的影响

本文研究了动载磨损条件下夹杂物的数量、形态与分布对铸钢耐磨性的影响及其作用机理．试验表明，夹杂物在动载磨粒磨损过程中的作用与磨损机理密要相关，夹杂物的存在，增加了裂纹形核的机率，导致磨损率增加．减少夹杂物的数量，改善夹杂物的形态与分布能提高铸钢的耐磨性