激光选区熔化成形S136模具钢热处理组织和性能研究

激光选区熔化是非平衡凝固过程,成形过程会产生热应力及组织应力,造成金属零件开裂、变形等缺陷,后期热处理是改善激光选区熔化金属零件微观组织和提升性能的有效手段。本文研究了后期热处理参数（热处理温度、保温时间及冷却方式）对激光选区熔化成形的S136模具钢零件微观组织和性能的影响。结果表明:最优热处理参数为1050℃,保温30 min,水冷。在最优热处理工艺下S136模具钢试样洛氏硬度达到HRC 53.7,比热处理之前提高了8.6%,洛氏硬度标准差比热处理之前降低了37.14%,硬度均匀性得到显著改善;试样的耐磨性、最大显微硬度和最大弹性模量比热处理前分别提升33.5%、3.3%和8.6%;试样的熔池形态鳞状形貌结构消失,碳化物相CrFe₇C_0.45溶解,组织均匀,基本呈现各向同性特征。     

影响40Mn钢链片淬回火硬度的原因分析

采用金相显微镜、洛氏和显微硬度计对40Mn钢链片淬火硬度不足的原因进行分析,并探讨影响淬回火试样显微组织和硬度的因素。结果表明,40Mn钢链片淬回火后表面脱碳300μm左右时,表面洛氏硬度只有HRC 16.8;脱碳66～84μm时,表面洛氏硬度约为HRC 30,表面洛氏硬度随脱碳层的增加而急剧降低。较高的淬火加热温度能促进马氏体转变,回火组织更粗大,从而提高淬火硬度。40Mn钢热轧状态容易形成带状组织,带状组织在热处理时增加奥氏体化难度,从而影响淬硬性。理论计算40Mn钢的Ac_3点为795℃,6 mm厚度的试样淬火所需最小保温时间约为7 min。     

电动工具用换向器材料—新型Cu-Cr-Zr合金研究

本文研究了电动工具用换向器铜合金的成分、加工及热处理工艺,确定其成分为 Cu-Cr-Zr-Mg,导电率>85%IACS,抗拉强度450～550MN/m~2,表面洛氏硬度>83,延伸率>10%,软化温度480℃。     

浅析 2018 版金属材料洛氏硬度试验方法

金属硬度试验是一种应用较为广泛的力学性能试验方法,同时也是一种应用较为广泛的强度性能试验技术,主要应用于检测材料的产品质量及热处理工艺。一般来说,洛氏硬度试验方法属于压入法测定金属材料硬度情况的技术范畴。目前,我国在金属材料洛氏硬度试验标准方面,主要于2018年完成修订,并于2018年12月1日正式实施。对比 2018 版与 2009 版两个版本主要内容,找出主要技术要求差异,并进行分析,以期为深入理解和正确执行新标注提供参考。     

焊后热处理对异种钢焊缝组织和性能的影响

选择高强钢和超低碳钢异种钢焊缝试样,进行不同温度的热处理,对比不同保温温度下焊缝区域的金相组织、力学、杯突和洛氏硬度等性能,研究保温温度对异种钢焊缝的影响。结果表明,900℃保温5min后,焊缝熔合度良好,焊缝强度较高,焊缝熔合区附近的组织较为细小;随保温温度升高,试样硬度呈下降的趋势,且热影响区的硬度比母材明显提高。     

0Cr17Ni7Al不锈钢热处理工艺研究

研究了热处理工艺对0Cr17Ni7Al不锈钢洛氏硬度的影响。将0Cr17Ni7Al不锈钢调整处理后冷却到15℃以下进行深冷处理,并保证调整处理和深冷处理的时间间隔小于1 h,可以降低组织的奥氏体稳定化程度,使其转变为马氏体组织,从而提高材料的洛氏硬度。经固溶处理—调整处理—深冷处理—时效处理,可以明显提高0Cr17Ni7Al不锈钢的洛氏硬度,为44～47,符合稳定使用标准的要求。     

洛氏硬度试验的不确定度评定

按金属材料洛氏硬度试验的基本要求,对高强螺栓的洛氏硬度用两种不同的方法进行了不确定度评定,并对评定结果进行分析,获得了有意义的结果。     

喷射成形轴承钢GCr15显微组织分析

对喷射成形轴承钢GCr15试样显微组织进行试验分析,发现喷射成形坯件沿轴向各位置均存在较多孔隙和疏松,坯件的组织为等轴晶,微观组织为珠光体团,晶界处渗碳现象明显,平均洛氏硬度值为HRC34.5。通过降低凝固速度、提高金属液过热度及降低载气量及冷/热态挤压可控制消除孔隙和疏松,并采取适当的热处理工艺减少晶界处碳化物的析出,进一步提高材料的综合性能。     

连续退火钢板表面洛氏硬度的影响因素研究

对在连续退火生产过程中采集的温度、粗糙度、时间变化的带钢表面洛氏硬度进行试验,对试验数据进行分析处理,在此基础上总结和探讨各因素在连续退火过程中对带钢洛氏硬度的影响。通过试验得出的经验公式HRB=132-26 935/R_m,可用来估测硬度值并指导生产。     

P20塑料模具钢低能耗热处理工艺的生产实践

应用光学显微镜,洛氏硬度计对P20塑料模具钢进行了显微组织观察和硬度测定。研究了不同热处理工艺下塑料模具钢的组织及其硬度的变化规律,为大生产试制P20塑料模具钢提供技术参数。     

模拟焊后消应力热处理样坯尺寸对厚板力学性能的影响

针对锅炉和压力容器钢钢板产品标准中模拟焊后消应力热处理样坯的建议尺寸为3T·3T·T这一要求,结合相关钢板产品信息,选择了不同钢级和规格的钢板,设计了三种不同尺寸的样坯进行了模拟焊后消应力热处理试验,并且取样进行力学性能测试。对拉伸和冲击试验结果进行分析之后得出,试验所用样坯尺寸对于试验结果并无明显影响,因此得出厚度50 mm以上并且淬透性较好的钢板可以用小试样代替标准规定的3T·3T·T的尺寸要求。     

Use of controlled heat treatment to predict mechanical properties in steel components

This paper investigates the non-destructive, experimental determination of mechanical properties, at any location within large steel forgings, through the use of controlled heat treatment. Industrial time–temperature data from heat treatment furnaces have been used as the surface temperature boundary condition in finite element models. The models have been used to determine the thermal history at specific locations of interest within a 95 tonne forging. Application of the predicted thermal history to a laboratory sized sample of material, using controlled heat treatment, results in macroscale material that has an identical thermal history to the points of interest within the forging. This sample material has been mechanically tested and compared to mechanical test results from the forging itself.     

润滑剂对温压FeSiAl磁粉芯性能的影响

采用温压成形工艺将水雾化Fe Si Al粉末制备成磁粉芯;用X射线衍射对原始粉末和经过绝缘包覆及热处理的粉末进行物相分析;采用软磁交流测试仪测量磁粉芯的磁损耗;利用精密磁性元件分析仪测量样品的磁导率。混合不同质量分数的硬脂酸锌和聚乙二醇(PEG)作为温压润滑剂,并研究其对Fe Si Al磁粉芯性能的影响。结果表明,1 100 MPa/100℃的温压成形条件下,当硬脂酸锌和PEG质量比为2:3,添加温压润滑剂的质量分数为1.3%时,磁粉芯生坯密度达到最大值5.75 g/cm3,热处理后为5.74 g/cm3。660℃×1 h热处理后,100 k Hz下,相应的有效磁导率?e达到137.9;350 k Hz/50 m T下磁损耗Ps为81.78 W/kg。     

高温合金母合金真空冶炼中炉前快速分析的取制样方法探讨

高温合金母合金的成分范围控制较窄,应用综合检测手段,建立了高温合金母合金中主量、微量及痕量元素的炉前快速分析方法.使用φ30 mm的铝刚玉材质取样杯,在真空感应炉中采用二次浸没法取高温合金母合金熔液,凝固后快速冷却完成取样.在样品的尾部切割厚约8 mm的第1试样,用于辉光放电质谱仪(GDMS)测试其痕量元素含量;在剩下...     

Computer-derived nuclear features distinguish malignant from benign breast cytology

This article describes the use of computer-based analytical techniques to define nuclear size, shape, and texture features. These features are then used to distinguish between benign and malignant breast cytology. The benign and malignant cell samples used in this study were obtained by fine needle aspiration (FNA) from a consecutive series of 569 patients: 212 with cancer and 357 with fibrocystic breast masses. Regions of FNA preparations to be analyzed were converted by a video camera to computer files that were displayed on a computer monitor. Nuclei to be analyzed were roughly outlined by an operator using a mouse. Next, the computer generated a "snake" that precisely enclosed each designated nucleus. The computer calculated 10 features for each nucleus. The ability to correctly classify samples as benign or malignant on the basis of these features was determined by inductive machine learning and logistic regression. Cross-validation was used to test the validity of the predicted diagnosis. The logistic regression cross validated classification accuracy was 96.2% and the inductive machine learning cross-validated classification accuracy was 97.5%. Our computerized system provides a probability that a sample is malignant. Should this probability fall between 30% and 70%, the sample is considered "suspicious," in the same way a visually graded FNA may be termed suspicious. All of the 128 consecutive cases obtained since the introduction of this system were correctly diagnosed, but nine benign aspirates fell into the suspicious category.(ABSTRACT TRUNCATED AT 250 WORDS)     

辐射管辊底式热处理炉数学模型的研究与应用

采用假想面法建立了辐射管辊底式热处理炉炉内钢板加热的二维数学模型,开发了辐射管热处理炉模型控制系统。该模型包括钢板温度跟踪和炉温设定两个模块,钢板温度跟踪可以实时计算钢板在炉内的温度,为钢板热处理进入保温状态提供依据;炉温设定可以计算不同钢种、不同厚度、不同热处理目标温度下钢板对应的炉温设定值范围,用于指导生产。该模型已成功应用于某公司的辐射管辊底式热处理炉上,通过埋偶试验对模型进行了验证。试验结果表明,模型计算精度在±5℃以内,控制效果良好。     

Effect of internal heating during hot compression on the stress-strain behavior of alloy 304L

The temperature change due to the conversion of mechanical deformation to internal heat and its effect on the as-measured stress-strain behavior of alloy 304L was investigated by means of initially isothermal (compression specimen, dies, and environment at same temperature at initiation of test), constant strain rate, uniaxial compression of laboratory-sized cylindrical specimens. Strain rate was varied in the range 0.01 to 1 s⁻¹, where the thermal state of the test specimen varied from nearly isothermal to nearly adiabatic, respectively. Specimens were deformed in the temperature range of 750 °C to 1150 °C to a strain of 1. The change in specimen temperature with applied strain was calculatedvia finite-element analysis (FEA) from the asmeasured stress-strain data. Selected predictions were confirmed with embedded thermocouples to verify the model employed. Temperature was found to increase monotonically with strain at a strain rate of 1 s^-1, consistent with what is theoretically expected for the adiabatic case. At the 0.1 and 0.01 s^-1 rates, the sample temperature initially increased, peaked, and then decreased as the sample thinned and the contact area between the sample and the cooler dies increased. As-measured stress was corrected for softening associated with deformational heating by interpolation between the various instantaneous stress-temperature behaviors. The resulting isothermal flow data are compared to those predicted by a conventional method that employs an empirical estimate of the heat retention efficiency of the test specimen, assumed dependent on strain rate but independent of strain, to reduce the increase in temperature calculated for the adiabatic case. Differences between the calculated isothermal stress-strain data from the two methods are discussed. Values for the apparent activation energy of deformation and the strain to the peak in the flow curve, which is associated with the onset of dynamic recrystallization, determined from isothermal stress-strain data differed significantly from those obtained from the as-measured compression test data. Formerly Senior Systems Engineer with EG&G Rocky Flats, Inc., is retired.     

使用2A02合金冷拉棒材毛料的锻件热处理工艺研究

使用2A02H112φ25mm影响,通过试验调整桨叶锻件热处理制度,使产品满足标准要求,应用于生产取得良好效果。:冷拉棒材做毛料的桨叶锻件的热处理工艺,首次提出了退火、冷拉操作对后续热处理工艺的     

Gas Tungsten Arc Welding of 316L Austenitic Stainless Steel with UNS S32205 Duplex Stainless Steel

In the present work, dissimilar welding between UNS S32205 duplex stainless steel (DSS) and 316L austenitic stainless steel (ASS) was performed by using gas tungsten arc welding and ER2209 filler at two different heat inputs (0.52 and 0.98 kJ/mm). Microstructures were characterized using reflected light optical microscope and scanning electron microscope. Micro-hardness and tensile properties were measured across the weld for both the heat inputs. The microstructure of the welded region was primarily austenitic (for both heat inputs) with Widmanstätten morphology. The grain size of the heat affected zone on DSS side was very large (~200 µm) for the high heat input sample with the presence of partially transformed austenite and acicular austenite. The precipitation of intermetallic phases and carbides was not observed for both the heat inputs. The proportion of ferrite in the weld metal (as measured by feritscope) was higher for the high heat input sample than the low heat input sample. During the tensile test, fracture occurred in 316L ASS base metal (because of its lower strength) in ductile manner. For high heat input welds, the impact tested sample showed the presence of fine spherical precipitates rich in Cr, Mn and Fe in the fracture surface of weld metal.