淬火工艺对塑料模具用钢40Cr组织及性能的影响

研究了不同淬火温度、不同淬火介质对塑料模具用钢40Cr组织及力学性能的影响.结果 表明:40Cr钢经水淬后得到组织均为马氏体.随淬火温度的升高,粗针状的马氏体束增多,可降低钢的强度、硬度及韧性;油淬后得到组织均为马氏体+贝氏体+少量铁素体,随着淬火温度的提高,原始奥氏体晶粒长大,马氏体组织含量增多,但获得较粗大的马氏体组织,贝氏体含量逐渐减少;不同淬火温度下,水冷试样硬度均高于油冷试样;水淬试样回火后由于细晶强化作用,使强度、硬度及冲击韧性均高于油淬.840℃水淬试样经过600℃回火可获得最佳综合力学性能.     

P20塑料模具钢的组织对抛光性能的影响

测试和研究了P20塑料模具钢900℃淬火马氏体和900℃加热450℃等温淬火粒状贝氏体在400～700℃回火的托氏体组织的硬度和表面粗糙度。结果表明，P20钢回火后的硬度越高，粗糙度越低，抛光性能越好；马氏体回火组织较粒状贝氏体回火组织细小，具有良好的抛光性能；当P20模具钢的硬度HRC为32～38时，钢的抛光性能稳定。     

等温温度对超细贝氏体钢组织演变规律的影响

通过热膨胀试验研究实验钢的等温转变动力学,采用盐浴等温淬火工艺制备超细贝氏体组织,利用扫描电镜、透射电镜和X射线衍射仪定量分析工艺参数对微观组织结构的影响.结果显示:实验钢室温组织由大量超细板条状贝氏体铁素体和板条间分布的薄膜状奥氏体的复相组织构成,210℃等温淬火得到的贝氏体板条间距细化到约60 nm,硬度约为HBW610;实验钢的最终组织特征取决于发生贝氏体转变的等温温度和等温时间,等温温度越低时贝氏体转变完成需要的等温时间越长.      

回火对Si-Mn-Mo系贝氏体钢组织性能的影响

研究了淬火后不同温度回火对Si-Mn-Mo系贝氏体钢显微组织与力学性能的影响.结果表明,采用淬火后回火的工艺可以显著提高Si-Mn-Mo系贝氏体钢的强度和塑性.淬火后300℃回火与350℃回火,该钢的力学性能相差不大,而450℃回火后强度、硬度相对较低,韧塑性略有提高.组织观察表明,该钢为贝氏体铁素体和残余奥氏体(片状和块状M-A岛)的复合组织,适当温度回火可以促进块状M-A岛分解,增加板条铁素体含量,提高残余奥氏体的机械稳定性,进而稳定其组织性能..     

核电站用SA738Gr.B钢板热处理工艺研究

为满足SA738Gr.B核电站用钢较高的性能要求,在实验室试验的基础上,研究了工业化生产热处理工艺参数对钢显微组织和力学性能的影响。结果表明,钢板淬火时冷却速度5℃/s时,能够避免先共析铁素体的析出;淬火温度较高时,钢板具有更细小和均匀的板条贝氏体;随着淬火加热的保温时间延长,晶粒组织粗化且铁素体含量减少;随着回火温度的升高,晶粒粗化,同时贝氏体含量减少,铁素体含量增多;在工业化生产中,较大淬火水量下钢板的拉伸性能更优;随着回火时间的延长,钢板强度下降而冲击韧性提高。以920℃×2.0 min/mm加热、较高水量的Q2工艺淬火,并采用650℃×1.5min/mm的工艺回火,可使钢板的强韧性达到最佳匹配。     

回火工艺对贝氏体辙叉心轨钢组织性能影响研究

研究了Si—Mn—Cr低碳贝氏体钢在正火和回火过程中的组织转变和性能变化。结果表明:经350℃回火后具有良好的强韧配合,新型贝氏体钢屈服强度为1 196 MPa,抗拉强度为1 437 MPa,伸长率和断面收缩率分别为13%和50%,冲击韧性为72 J/cm~2,强韧性配合明显高于普通及淬火珠光体钢轨钢。而在450℃～600℃回火时出现明显的回火脆性。通过研究回火后的组织转变及残余奥氏体热稳定性、机械稳定性的变化,探讨了无碳贝氏体韧化及脆化机理,提出了适于该钢的最佳回火工艺。     

淬火分配工艺对低碳低合金钢组织与性能的研究

研究了0.15C-Mn-Si-Cr低碳低合金钢在Ms点以下不同温度预淬火-碳分配工艺(QP工艺)及贝氏体转变对钢组织与性能影响。结果表明,实验钢经QP处理后获得贝氏体/马氏体复相组织,与淬火回火钢相比能获得更多的残余奥氏体量,随着淬火碳分配温度的升高,钢中残余奥氏体量增加,等温温度超过310℃后,钢中析出碳化物,残余奥氏体量减少。在250℃预淬火温度等温碳分配淬火,钢的冲击韧性显著高于传统的淬火回火钢。     

MC5中间辊硬度偏低、不均匀的原因分析

通过对批量性MC5中间辊硬度偏低、不均匀的情况进行试验、分析,发现淬火温度偏高导致残余奥氏体量增加,造成回火后硬度偏低;残余奥氏体在350℃左右回火时转变为下贝氏体类组织,使得残余奥氏体在回火后对硬度没有贡献.     

等温处理对中碳超高强度弹簧钢组织与力学性能的影响

研究了等温处理对中碳超高强度弹簧钢组织与力学性能的影响.结果表明,在325～375℃等温可以获得无碳化物贝氏体/马氏体复相组织;奥氏体化温度对贝氏体/马氏体复相组织的影响很大,从875℃升高到930℃,强度升高,但其塑性、冲击韧性和断裂韧性显著降低.试验范围内,在875℃保温30 min,325℃等温120 s油淬后,在300℃进行回火处理2 h,可获得强韧性配合良好的贝氏体/马氏体复相组织,其断裂韧性KIC值为83MPa·m1/2,是相同强度水平下常规淬火回火马氏体组织的1.5倍.     

热处理工艺对EH690级特厚钢板心部组织及性能的影响

针对不同热处理工艺对EH690级特厚钢板心部组织和性能的影响展开研究,结果表明：经过在线淬火+回火处理,钢板心部的强度能够满足性能要求,但冲击韧性极差,显微组织为粗大粒状贝氏体和珠光体的混合组织;一次淬火+回火处理后,强度下降明显,冲击性能有所改善,但是不能满足-40℃低温冲击吸收功≥69 J的要求,存在混晶,组织为粒状贝氏体+少量马氏体;二次淬火+回火处理后,强度整体偏高,冲击功均值满足标准要求,强韧性匹配程度一般,晶粒细化明显,马氏体含量占比增多。通过调整回火温度,最终获得晶粒细小均匀、以高密度位错回火索氏体为主的组织,钢板心部强韧性匹配较好。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。