Hot Deformation Behavior of an Ultra-High-Strength Fe–Ni–Co-Based Maraging Steel

Hot processing behavior of an ultra-high-strength Fe–Ni–Co-based maraging steel was studied in temperature range of 900–1200 °C and strain rate range of 0.001–10 s~(-1). Deformation processing parameters and optimum hot working window were characterized via flow stress analysis, constitutive equation construction, hot processing map calculation and microstructure evolution, respectively. Critical strain value for dynamic recrystallization was determined through theoretical mathematical differential method: the inflection point of θ–σ and -αθ/ασ-σ curves. It was found that the flow stress increased with the decrease in deformation temperature and increase in the strain rate. The power dissipation maps in the strain range of 0.1–0.6 were entirely similar with the tendency of contour lines which implied that strain had no strong effect on the dissipation maps. Nevertheless, the instability maps showed obvious strain sensitivity with increasing strain, which was ascribed to the flow localization and instability. The optimized hot processing window of the experimental steel was obtained as 1100–1200 °C/0.001–1 s~(-1) and 1000–1100 °C/0.001–0.1 s~(-1), with the efficiency range of 20–40%. Owing to high Mo content in the experimental steel, high dynamic activation energy, Q = 439.311 kJ mol~(-1), was achieved, indicating that dynamic recrystallization was difficult to occur in the hot deformation process, which was proved via microstructure analysis under different hot deformation conditions.     

Deformation Behavior of Finely-Lamellar Pearlite During Multiple Cold Plastic Deformation of Eutectoid Steel

Metal Science and Heat Treatment - Deformation behavior of finely-lamellar pearlite in steel with 0.78% C during multiple cold plastic deformation by drawing is considered. It is revealed that...     

汽车轮胎帘线用共析钢微观组织对硬化行为的影响

研究了汽车轮胎帘线用共析钢的显微组织对硬化行为的影响。结果表明,片状珠光体的共析钢具有较高的抗拉强度,但断面收缩率和屈服强度较低。球状珠光体使共析钢的抗拉强度、断面收缩率和屈服强度都有所提高。细化组织和超细化组织加工硬化不明显,表现出很好的塑性和韧性。     

Wear Behavior of Harmonic Structured 304L Stainless Steel

Wear behavior of a harmonic structured 304L austenitic stainless steel with periodically distributed fine and coarse grains was examined and compared with a sintered non-harmonic structured 304L stainless steel and a low carbon conventional 304 stainless steel using fretting wear tests at varying loads in ball-on-flat contact configuration. Characterization was accomplished using scanning electron microscope, energy-dispersive spectroscopy, optical profilometry and Raman spectroscopy. Coefficient of friction and wear volume were minimum at intermediate normal load of 5 N, whereas maximum at 10 N for the harmonic stainless steel compared to other two steels. Harmonically distributed fine- and coarse-grained structure attributes to the higher wear rate of the harmonic structured steel at higher load because of differential interaction of the ball with the harmonically distributed hard (fine) and relatively soft (coarse) regions.     

高强韧耐磨铸钢摩擦磨损行为研究

高强韧耐磨铸钢经930℃×2h淬火(油淬)+240℃×2h回火+240℃×2h二次回火后,具有较高的强韧性,硬度≥54HRC,冲击韧度≥43J/cm2,组织为回火马氏体+少量的残余奥氏体。对热处理工艺优化后的耐磨钢在MMS-1G高温高速销盘摩擦磨损试验机上进行摩擦磨损性能研究,运用JSN-5610V扫描电镜分析磨损形貌。结果表明:在一定摩擦速度(50m/s)下,随着载荷的增加,磨损量明显增大,摩擦系数不断减少,表明载荷作用是影响试样钢磨损量的一个重要因素;在一定载荷(40N)作用下,磨损量随摩擦转速的提高先增大后减小,磨损转速在低载荷作用时对材料的磨损量影响不大。     

加工硬化对高锰钢磨料磨损性能的影响

利用喷丸技术,在高锰钢表面制备出具有纳米晶结构特征的表层,60min喷丸样品表面的晶粒尺寸约为3～8nm。2min喷丸样品表面的晶粒尺寸为30-40nm。随着喷丸处理时间的增加,表面硬度增加,样品起始硬度为256HV,120min喷丸处理后,表面硬度增加到774HV。二体磨料磨损试验结果表明,在玻璃砂纸磨损,经2min喷丸的材料耐磨性相对于喷丸前提高了70％。喷丸前、后样品主要为微观切削,但过长的喷丸时间,导致表面产生微裂纹,使耐磨性下降;而刚玉砂纸磨损,喷丸处理不能提高样品的耐磨性。     

5CrNiMo钢的高温滑动磨损特性

研究了５ＣｒＮｉＭｏ钢在４００℃、５００℃、５５０℃及６００℃等不同温度下的滑动磨损行为，利用扫描电镜、波谱仪及Ｘ射线衍射仪对磨损面形貌及成分进行了分析。结果表明：５ＣｒＮｉＭｏ钢的磨损机制随温度而异，表面氧化膜有减摩、抗磨作用。     

A Study on the Wear Behavior of Cast Boron Steel

In this study, a wear-resistant Cast Boron Steel (CBS) of nominal composition 0.25% C, 1.18% B, 1.27% Cr, 0.85% Mn, and 0.69% Si was oil-quenched at different temperatures. The effect of quenching temperature on the microstructure and wear resistance of CBS was investigated. Moreover, the wear resistance between CBS and high chromium cast iron was compared. The results show that a martensite matrix can be obtained by quenching from 900 to 1050 °C, and the wear resistance of quenched CBS is excellent, which reaches the level of high chromium cast iron. The reason behind the fact that CBS has excellent wear resistance is discussed.     

钢的共析分解理论研究的进展

珠光体是共析铁素体和共析渗碳体（或碳化物）构成的整合组织而不是机械混合物。珠光体的形核长大是以界面扩散为主进行的。过冷奥氏体中会出现贫碳区和富碳区的涨落,加上随机出现的结构涨落、能量涨落,三者非线性的因果正反馈相互作用,导致贫碳区和富碳区分别建构铁素体和渗碳体（或碳化物）的核坯,组成珠光体晶核（F+Fe₃C）。铁素体和渗碳体是共析共生、台阶式协同长大,不存在领先相计算表明,珠光体临界晶核半径为70～152 nm,临界形核功△G^*=155～292 J/mol。"相间沉淀"是殊光体转变产物,应用共析分解的新理论解释了"相间沉淀"过程。珠光体片间距与奥氏体过冷度的关系是非线性的。发现珠光体表面也有浮凸现象,是新旧相比体积不同所致。     

45钢上几种表面涂层的微动损伤行为和机理研究

在ＳＲＶ微动试验机上研究了五种表面改性层：离子镀ＴｉＮ激光硬化,磁控溅射ＭｏＳ２离子渗流,电刷镀Ｎｉ－ＭｏＳ２的抗微动磨损性能,结果表明：以高硬度为特征的抗磨必性层,比低摩擦因数的减摩改性层,能更有效地改善基体４５钢的抗微动损伤性能,其微动损伤机制均为颗粒脱落,但由于各表面改性层性能的不同,共损伤过程亦有差别。     

Carbide Precipitation Behavior and Wear Resistance of a Novel Roller Steel

High speed steel, which contains more alloy elements, cannot be used to manufacture the forged work roll. Therefore, a novel roller steel was designed on the basis of W6Mo5Cr4V2 (M2) steel. In this study, the carbide precipitation behavior and wear resistance of the novel roller steel were investigated. The Fe-C isopleths were calculated by Thermo-Calc to determine the carbide types, which were precipitated at different temperatures. The phase transformation temperatures were measured by differential scanning calorimeter and then the characteristic temperatures were designed. The phase structures quenched from the characteristic temperatures were measured by x-ray diffraction and transmission electron microscopy. The typical microstructures were observed by field emission scanning electron microscopy with Energy Disperse Spectroscopy. The hardness and wear resistance of the novel roller steel were measured. The results show that the precipitation temperatures of austenite, MC, M₆C, M₂₃C₆, and ferrite are 1360, 1340, 1230, 926, and 843 °C respectively. When the specimen is quenched from 1300 °C, only MC precipitates from the matrix. At 1220 °C, MC and M₂C precipitate. At 1150 °C, all of MC, M₂C and M₆C precipitate. Relationship between mass fraction of different phases and temperature were also simulated by Thermo-Calc. The hardness of the novel roller steel is a little lower than that of M2 steel, however, the wear resistance of the novel roller steel is a little higher than that of M2 steel with the increase of wear time.     

Friction and Wear Behavior of 30CrMnSiA Steel at Elevated Temperatures

The friction and wear properties of 30CrMnSiA steel were investigated at elevated temperature from 100 to 600 °C. Thereafter, the wear debris and worn surfaces were examined to understand the wear mechanisms. The remained debris with relatively high hardness created three-body abrasion at lower temperatures (100-300 °C). Abrasive wear prevailed at the conditions with high friction coefficients and wear rates. A significant change in friction and wear behavior occurred at 400 °C. At the temperature of 400 °C, oxidation induced mild wear was found because of the formation of load-bearing oxide film. Both the friction coefficients and wear rates of the steel were lowest at 400 °C. At the temperatures of 500-600 °C, a mild-to-severe wear transition occurred which resulted in an increase in the friction coefficients and wear rates of the steel. This is related to the decrease in the strength of matrix and hardness of worn surfaces and subsurfaces. The predominant wear mechanism is considered to be severe abrasive, adhesive wear and a fatigue delamination of the oxide film.     

共析钢中片状珠光体脆化钢材的机理研究

观测了片状珠光体钢在不同热处理状态时的显微组织和断口形貌,对比了不同热处理方式对片状珠光体钢组织及性能的影响,借助断裂模型分析了片状珠光体组织容易导致钢材脆断的作用机理,并讨论了影响片状珠光体形成的因素。结果表明,片状珠光体位向明显、区域偏析严重是钢材脆断的重要因素;片状珠光体钢断口组织粗大,解理面呈河流状花样,解理台阶和撕裂棱较少;低温退火很难改善片状珠光体钢的脆性,而高温正火则能显著提高其韧性;片状珠光体内交界面和相界面越多,韧性越强,而提高过冷度减小片间距能增加相界面;共析钢中碳含量处于共析点决定了其冷却过程中易形成片状珠光体组织。     

Relationship Between Microstructure and Corrosion Behavior of Cr12Ni3Co12Mo4W Ultra-High-Strength Martensitic Stainless Steel

The effect of tempering temperature on the microstructure and corrosion behavior of Cr12Ni3Co12Mo4W ultra-high-strength martensitic stainless steel was investigated using transmission electron microscopy, atomic force microscopy, X-ray diffraction, and electrochemical tests. The microstructures of the ultra-high-strength martensitic stainless steel consisted of some retained austenite and lath/plant martensite with the carbides distributed within the matrix and at the grain boundaries. Tempering of the steel for 4 h at various temperatures resulted in various carbide grain sizes and different amounts of the retained austenite. The results showed that larger carbide grains led to diminished corrosion resistance, whereas larger amounts of the retained austenite resulted in improved corrosion resistance. The steels exhibited good corrosion resistance in 0.017 mol/L NaCl solution and exhibited pitting corrosion in 0.17 mol/L Na Cl solution. The martensite and prior austenite crystal boundaries dissolved in solution with pH 1.     

爆炸硬化对高锰钢滑动磨料磨损性能的影响

对Mn13Cr2高锰钢进行了爆炸硬化处理,并以120#氧化铝砂纸为磨料,应用ML-10型滑动磨损试验机对比研究了爆前、爆后高锰钢的滑动磨损性能,以探讨爆炸硬化对高锰钢滑动磨损性能的影响.结果表明:爆后高锰钢的滑动耐磨性是爆前的1.07～1.32倍,爆炸硬化弥补了高锰钢在滑动磨损过程中加工硬化能力的不足,使其滑动耐磨性得到有效改善.爆后高锰钢磨面仅出现少量氧化铝磨料,磨损产生的犁沟和划痕明显浅而窄,且磨损面相对平整、光滑.     

一种Cr25系耐热钢的组织及磨损行为研究

采用金相显微(OM)、X射线衍射(XRD)、扫描电镜(SEM)、万能力学试验机以及摩擦磨损试验等方法,研究了一种Cr25系耐热钢的组织、相结构、力学性能以及在室温、100℃、260℃下的摩擦磨损特性。研究结果表明:该种Cr25系耐热钢由α相和(Fe·Cr)_(23)C_6(KI)型碳化物相组成,其室温抗拉强度高、塑性差,冲击韧度低于6 J/cm2。在室温下,合金的磨损机制为磨粒磨损,随着磨损温度的增加,摩擦热效应增强,合金的磨损机制逐渐转变为磨粒+粘着磨损;摩擦系数由室温下的0.6逐渐降低到100℃下的0.4,到260℃时,其摩擦系数低至0.35,且其未随磨损时间的延长而显著变化;磨损量随磨损温度的增加逐渐降低。     

Research on Oxidation Wear Behavior of a New Hot Forging Die Steel

Dry sliding tests for the hot forging die steel DM were performed in air under the test temperature at 400-700 °C and the time of 0.5-4 h by a UMT-3 high-temperature wear tester. The wear behavior and characteristics were studied systematically to explore the general characters in severe oxidation conditions. The results showed that a mild-to-severe oxidation wear transition occurred with an increase in the test temperature and duration. The reason was clarified as the unstable M₆C carbides coarsening should be responsible for the severe delamination of tribo-oxide layer. More importantly, an intense oxidation wear with lower wear rates was found when the experimental temperature reaches 700 °C or after 4 h of test time at 600 °C, which was closely related to the degradation behavior during wear test. Furthermore, a new schematic diagram of oxidation wear of DM steel was proposed.     

Wear Behavior and Mechanism of H13 Steel in Different Environmental Media

Sliding wear tests were performed for H13 steel in atmosphere, distilled water, 3.5% NaCl, and 5% NaOH water solutions under various loads on a pin-on-disk wear tester. The results showed that for different environmental media, the wear rate of H13 steel in atmosphere was the maximum and that in 3.5% NaCl solution was the minimum. The maximum wear rate in atmosphere was caused by a larger quantity of heat produced in the friction process. In this case, the adhesive wear prevailed. In three wet environments, the mild wear prevailed due to the good lubrication and cooling capacity of media as well as corrosion product film on worn surface. In distilled water, the wear mechanism was a typical fatigue wear. On the other hand, in 3.5% NaCl and 5% NaOH solutions, corrosive wear prevailed. The minimum wear rate in 3.5% NaCl solution was attributed to the protective function of corrosion product film. On the contrary, noncompact corrosion product film in 5% NaOH solution resulted in higher wear rate.     

人工海水溶液中系泊链钢的腐蚀磨损行为

目的 以CM490钢为研究对象,定量探究海洋环境下系泊链钢摩擦磨损和电化学腐蚀之间的耦合作用。方法 利用科斯特CS2350电化学工作站和Rtec摩擦磨损试验机开展CM490系泊链钢在人工海水环境下的腐蚀摩擦磨损实验。通过分析极化曲线、开路电位、摩擦因数、表面形貌及元素分布,定量分析电化学腐蚀体积损失量和摩擦磨损体积损失量,揭示腐蚀、摩擦磨损之间的交互作用机理。结果 CM490钢材料总体积损失速率随载荷增加而提高,在20、50、80N下分别为4.2×10^-2、6.5×10^-2、7.9×10^-2mm³/h;开路电位峰值随着载荷增加而增高,80 N下峰值最大,增幅约为0.095 V,表明腐蚀磨损产物与基体间存在电位差,形成电偶腐蚀以致加深材料的腐蚀程度;磨痕区域腐蚀磨损损失为材料失重主体,其损失量约占总损失量的95.80%～96.82%;腐蚀和磨损的交互作用显著促进材料损失,占磨痕区总失重量的47.14%～49.37%;腐蚀对摩擦磨损损失的促进量占腐蚀磨损交互作用量的98.32%～98.65%,表明交互作...