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1.
通过TMCP研究了低碳锰钢和添加微量Nb的低碳锰铌钢的组织和力学性能的影响因素.研究了Nb对实验钢显微组织和力学性能的影响.Nb的添加能够细化铁素体晶粒,促进铁素体转变,对贝氏体形成有一定的抑制作用.相对低碳锰钢来说,铌的加入减少了贝氏体的体积分数,贝氏体强化效果减弱,钢的屈强比升高.通过增加冷速和降低卷取温度,可以使低碳锰铌钢获得一定量的贝氏体,综合性能较佳.低碳锰铌钢的主要强化机制有细晶强化、贝氏体相变强化和析出强化.  相似文献   

2.
武会宾  巨彪  车英建 《工程科学学报》2016,38(12):1741-1746
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.   相似文献   

3.
利用膨胀仪测定了14CrlMoR钢(/%:0.01C,0.66Si,0.80Mn,0.006P,0.003S,1.72Cr,0.31Mo,0.01Nb)的临界点及连续冷却转变曲线并研究了冷却速度对试验钢的组织及显微硬度的影响。结果表明,当冷却速度为0.1~1℃/s时,试验钢的转变组织为铁素体和珠光体;2~5℃/s时,试验钢得到铁素体、珠光体以及少量粒状贝氏体的混合组织;10℃/s时,试验钢组织为铁素体和粒状贝氏体;15~20℃/s时为板条贝氏体组织;25~50℃/s时,该钢得到板条贝氏体和马氏体的混合组织。  相似文献   

4.
《钢铁》2017,(12)
为了探索含铜中碳硅锰钢连续冷却转变过程中的相变规律,采用DIL805L型膨胀仪研究了铜对中碳硅锰钢连续冷却过程中显微组织和硬度的影响,借助高分辨透射电镜研究了连续冷却过程中含铜相的析出行为。结果表明,在中碳硅锰钢的连续冷却过程中,铜的加入使得铁素体转变的孕育期延长,且降低贝氏体和马氏体开始转变温度。富铜颗粒在铁素体中弥散析出,细化连续相变组织。冷却速度小于21℃/s时,含铜中碳硅锰钢由于富铜颗粒析出以及贝氏体和马氏体组织增加引起显微硬度增加。当冷却速度大于21℃/s时,铜反而会降低钢中贝氏体和马氏体组织的显微硬度。  相似文献   

5.
通过Gleeble-3800热模拟机,研究了一种胀断连杆用中碳非调质钢的连续冷却转变组织变化规律,分析了冷却速度对转变组织和显微硬度的影响.结果表明,当冷却速度为0.1~3℃/s时,组织为铁素体+珠光体,当冷却速度大于5℃/s时,开始发生贝氏体转变,随着冷却速度提高,贝氏体含量增多,并在速度大于15℃/s时发生马氏体转变.实验钢的显微硬度随着冷却速度的提高而增加.  相似文献   

6.
通过测定20Cr H钢的CCT曲线,以及不同冷速下连续冷却转变产物的显微组织和对应的硬度值,研究冷却速度对组织及硬度的影响,为该钢热处理工艺的制定提供依据。结果表明:冷速为1000℃/h,转变产物为共析铁素体+珠光体;当冷速增加为250℃/min时,出现了贝氏体组织;而当冷速为20℃/s时,产物为贝氏体+马氏体组织;冷速为50℃/s时,转变产物为完全马氏体组织。  相似文献   

7.
对渗碳齿轮用钢17Cr2Ni2Mo进行了不同温度和不同时间下的等温正火工艺试验,采用金相显微镜和布氏硬度计,研究分析了其显微组织和硬度的变化。结果表明,同一温度下,保温时间越长,贝氏体含量越少,先共析铁素体和珠光体含量越多,布氏硬度越小;同一保温时间下,保温温度越高,贝氏体含量越少,布氏硬度越大。综合考虑,925℃奥氏体化2 h后,再在680℃下保温4 h,17Cr2Ni2Mo钢可获得边部为铁素体+珠光体、心部为铁素体+珠光体+极少量贝氏体的组织,试样硬度为178~195HBW,有利于用户的后续机械加工。  相似文献   

8.
利用Formastor-FII型膨胀仪和Gleeble-3800热模拟试验机,结合显微组织观察和硬度测试,研究了压力容器用钢17MnNiVNbR的静态和动态连续冷却转变行为,并分析了热变形对相变行为的影响。实验结果表明:冷却速率较低时,17MnNiVNbR钢的相变组织为先共析铁素体和珠光体;随着冷却速率的增加,依次出现贝氏体和马氏体。热变形能提高铁素体、珠光体和贝氏体的相变温度,并使连续冷却转变曲线向左上方移动。  相似文献   

9.
采用MMS-300热模拟机测定了C-Si-Mn-Cr-Nb系980 MPa级高强度汽车双相钢的动态CCT曲线。实验结果显示:冷却速率在0.1~5℃/s范围内显微组织主要为铁素体+贝氏体;冷却速率达到5℃/s时铁素体转变结束,奥氏体全部转变为贝氏体;当冷却速率达到40℃/s时开始发生马氏体转变,显微硬度和抗拉强度均随冷却速率的增加而增加。  相似文献   

10.
在膨胀仪上测定了一种V、Nb微合金化高强钢筋的临界点Ac1、Ac3、Ar1和Ar3,获得了该钢在不同冷却速度下连续冷却时的膨胀曲线。采用膨胀法结合金相-硬度法,获得了试验钢的连续冷却转变曲线(CCT曲线),并研究了冷却速度对该钢组织及力学性能的影响。结果显示,当冷却速度为0. 1~2℃/s时,显微组织由铁素体和珠光体组成,显微硬度为193~250 HV30;冷却速度为3~5℃/s时,显微组织由铁素体、珠光体和贝氏体组成,硬度为268~287 HV30;冷却速度为5~30℃/s时,显微组织由铁素体、贝氏体和马氏体组成,硬度为287~424 HV30。对试验钢来说,控冷速度为0. 5~3℃/s之间最为理想,本文研究结果可作为高强度钢筋冷却过程的控制依据。  相似文献   

11.
转炉炉壳热应力分析   总被引:5,自引:1,他引:4  
任学平  郭志强  邹家祥 《炼钢》2001,17(6):47-49
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。  相似文献   

12.
13.
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)  相似文献   

14.
15.
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.  相似文献   

16.
17.
通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。  相似文献   

18.
Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.  相似文献   

19.
20.
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.  相似文献   

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