共查询到19条相似文献，搜索用时 406 毫秒
1.
杨雪春 《通化师范学院学报》2012,(12):19-20,37
对圆环链钢25MnV采用不同温度的亚温淬火回火的热处理工艺,并对热处理后的试样进行冲击和拉伸试验,结合实验数据和显微组织图片,分析影响圆环链疲劳强度的因素及显微组织的变化,为提高钢的疲劳寿命提供了理论依据． 相似文献
2.
钢中残余奥氏体的作用 总被引：1，自引：0，他引：1
葛心慧 《南通职业大学学报》1995,(1)
钢淬火后总存在一定量的残余奥氏体.残余奥氏体对钢性能的影响是一个受多因素影响的复杂问题.目前很少把残余奥氏体作为一个组成相,从残余奥氏体的数量、形态、稳定性、分布方式等诸方面来考察残余奥氏体在钢中的作用的这方面的报道,从而影响认识的深化.本文仅就残余奥氏体的数量、残余奥氏体的稳定性这两个因素对钢性能的影响作些探讨.一、残余奥氏体的数量对钢性能的影响及残余奥氏体数量的控制文献(1)用30CrMnSiNi_2A 钢作试样.最终热处理为900℃ × 40min加热保温后,进行230 ℃×60min的等温淬火十280℃×2h回火,用热水与干冰进行十50℃×15min(?)-60℃× 15min的循环冷处理,分别进行了三次与九次.残余奥氏体的量分别为5.8%和4.5%,然后进行多冲疲劳试验.试验结果证明:薄层状的残余奥氏体存在于马氏体板 相似文献
3.
《武汉工程职业技术学院学报》2016,(3)
采用超声疲劳试验技术对一种高强汽车弹簧用钢进行了超高周疲劳试验。采用扫描电镜对失效试样进行断口分析,并对断口特征区域尺寸进行了测量。结果表明:在0~10~6循环周次内失效的试样断口起源萌生于试样表面;而在10~6~10~9循环周次内失效的试样断口萌生于试样次表面或内部,且断口呈现鱼眼状特征,随着夹杂物处应力强度因子幅的减小,疲劳寿命增加;而粒状亮面处的应力强度因子幅并不随寿命变化而明显变化,基本为一常数。弹簧钢的超高周疲劳S-N曲线呈现二次下降型特性,其S-N曲线的形态特征跟试样夹杂物尺寸密切相关。 相似文献
4.
《武汉工程职业技术学院学报》2016,(4)
对一种高强汽车弹簧用钢分别进行了常规疲劳和超高周疲劳试验。常规疲劳试验频率为140Hz,超高周疲劳试验频率为20kHz。采用扫描电镜分别对失效试样进行断口扫描分析。结果表明,140Hz和20kHz下的疲劳断口表现出相似的特征,在106循环周次内失效的试样断口起源萌生于试样表面;而高周和超高周疲劳试样断口起裂于试样次表面或内部,且断口呈现"鱼眼"状特征。另外,超高周疲劳断口裂纹源周围存在粒状亮面特征区。弹簧钢的超高周疲劳S/N曲线呈现二次下降型特性,其S/N曲线的形态特征跟试样夹杂物尺寸密切相关。140Hz得到的疲劳试验结果与20kHz下的超高周疲劳试验结果有着明显的偏差,弹簧钢频率效应明显。 相似文献
5.
采用50kg真空感应电炉冶炼4炉不同成分的试验钢,然后对试验钢锭进行锻造和预备热处理,并对经过调质处理的锻件进行力学性能和微观组织检验、以及顶端淬火淬透性试验;通过对比分析,选用综合性能较好的低N材质试验钢开展淬火试验,经过分析淬火试样的微观组织和显微硬度,优化出最佳淬火温度,为研制8Cr4MoV低合金锻造超深淬硬层冷轧工作辊打下基础。 相似文献
6.
古人说:“学则需疑”。疑问是深入学习的起点,有“疑”才有“问”,有“究”才有“疑”。 在使用不同类型的试样(U型缺口或V型缺口)进行一次摆锤冲击弯曲试验时,得到的冲击韧性值是否相同?当交变应力循环对称时,疲劳强度用符号o_(-1)表示,当交变应力循环不对称时,疲劳强度该用什么符号表示?高速钢淬火时,“当钢中含4％的铬时,空冷就可使奥氏体转变成马氏体”,因此,空气也能作为淬火介质?将奥氏体化后的钢件先水后空气淬火的方法,称“双液淬火”好,还是称“双介质淬火”确切?共析钢,过共析钢完全奥氏体化,随之缓慢冷却,获得接近平衡状态组织的工艺,能否称为完全退火?将钢件加热 相似文献
7.
采用宏观及显微组织分析、扫描电镜分析和力学性能试验等方法对传动轴的断裂进行了失效分析。结果表明,该轴断裂属疲劳失效,轴端部键槽处在制造过程中存在淬火裂纹是导致疲劳断裂的主要原因。 相似文献
8.
基于与企业合作开发的00Cr9M合金钢,采用JMatPro软件模拟其平衡相图、过冷奥氏体等温转变曲线、连续过冷奥氏体转变曲线和再奥氏体化温度曲线并设计热处理工艺。通过显微组织观察、拉伸试验、冲击试验和硬度检测,研究不同淬火和回火温度对00Cr9M合金钢组织形貌演变和力学性能的影响规律。结果表明：在320℃回火工艺下,随着淬火温度的提高,00Cr9M合金钢逐渐完成再奥氏体均匀化转变,晶粒及其内部板条状回火马氏体组织逐渐粗化且晶界更加清晰;在820℃淬火、400℃回火工艺下,00Cr9M合金钢内部形成细小的超低碳回火马氏体并获得所有热处理工艺中最为卓越的综合力学性能,其中抗拉强度为1135MPa,屈服强度为869MPa,伸长率为12.5%,断面收缩率为73.0%,洛氏硬度为34.8 HRC,冲击吸收功为243J,满足抽油杆高强度、高韧性的力学性能要求。 相似文献
9.
复杂飞机结构裂纹萌生寿命确定的工程方法 总被引：1，自引：0，他引：1
采用静拉伸应变测量试验的方法,确定了典型飞机复杂结构在载荷作用下的应变分布,并准确判断出其疲劳危险部位。对典型飞机复杂结构模拟件进行了等幅加载疲劳试验,并在疲劳试验过程中采用着色探伤方法测得了疲劳裂纹扩展数据。在此基础上,提出并建立了一种适用于确定复杂结构疲劳裂纹萌生寿命的工程方法,包括疲劳裂纹萌生寿命反推法和含有不确定寿命样本的统计推断方法。根据该方法对试验样本疲劳数据进行处理得出了裂纹萌生中值寿命及其在95%置信水平下的单侧置信下限。 相似文献
10.
《实验室研究与探索》2015,(6):38-41
采用HL-5000型横流CO2激光加工机,应用宽带技术,选择合适的激光工艺参数,对QT600-3球墨铸铁和40CrMo电梯绳轮进行了激光相变硬化处理。研究了球墨铸铁和40CrMo激光淬火后显微组织的变化,球墨铸铁绳轮基体的显微组织为珠光体、铁素体和球状石墨,激光硬化层的显微组织为石墨球周围一般包围一层等轴状的马氏体和残余奥氏体,其外再围有变态莱氏体层。40CrMo绳轮基体组织为回火索氏体组织,激光硬化层的显微组织为细小马氏体和少量残余奥氏体。测量了淬硬层的性能,淬硬层的硬度可分别达到785HV0.1和767HV0.1,硬化层深度约为0.77 mm和0.75 mm,达到电梯绳轮的技术要求。绳轮实样耐磨性模拟试验表明:激光淬火后耐磨寿命有很大的提高,1987~2007年激光表面处理了电梯绳轮约2万只,全部投入装机使用。 相似文献
11.
This paper investigated the static and fatigue behaviors of steel and composite multi-leaf spring using the ANSYS V12 software.
The dimensions of an existing conventional leaf spring of a light commercial vehicle were used. The same dimensions were used
to design composite multi-leaf spring for the two materials, E-glass fiber/epoxy and E-glass fiber/vinyl ester, which are
of great interest to the transportation industry. Main consideration was given to the effects of material composition and
its fiber orientation on the static and fatigue behaviors of leaf spring. The design constraints were bending stresses, deflection
and fatigue life. Compared to the steel leaf spring, the designed composite spring has much lower bending stresses and deflections
and higher fatigue life cycles. 相似文献
12.
A newly developed pure rolling fatigue test rig with three contact points for bearing balls was used to perform rolling contact fatigue (RCF) tests. The fatigue properties of GCr15 steel balls and two kinds of Si3N4 ceramic balls (GSN-200 and NBD-200) produced with different technologies were compared. Ball surfaces were examined after failure with optical microscope and scanning electron microscope (SEM). It was identified by tests that the failure mode of ceramic balls was surface spall. The main factor of ceramic ball failure was principal tensile stress. Life tests data, summarized in accordance with the Weibull theory, showed that the life of GSN-200 balls was close to that of GCr15 balls, whereas the life of NBD-200balls was much longer than those of GSN-200 and GCr15. Under the same working condition, the temperature rise of all ceramic balls was lower than that of steel balls, and their crack propagation rates were slower than that of steel balls. 相似文献
13.
Wei Fuming Huang Zheng Zhu Yanian Zhou Jun Yu Heying Xu Ting Liu Feng Yao Yong 《上海大学学报(英文版)》1998,2(2):148-155
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14.
Improving the Fatigue Performance of the Welded Joints of Ultra-Fine Grain Steel by Ultrasonic Peening 总被引：2，自引：0，他引：2
Contrast tests were carried out to study the fatigue performance of the butt joints treated by ultrasonic peening, aiming at the improvement of ultrasonic peening treatment(UPT) on welded joints of a new material. The material is a new generation of fine grain and high purity SS400 steel that has the same ingredients as the traditional low carbon steel. The specimens are in two different states:welded and ultrasonic peening conditions. The corresponding fatigue testing data were analyzed according to the regulation of the statistical method for fatigue life of the welded joints established by International Institute of Welding(IIW). Welding residual stress was considered in two different ways: the constant stress ratio R = 0.5 and the Ohta method. The nominalstress-number (σ-N) curves were corrected because of the different plate thickness compared to the standard and because there was no mismatch or angular deformation. The results indicated that: 1 ) Compared with the welded specimens, when the stress range was 200 MPa, the fatigue life of the SS400 steel specimens treated by ultrasonic peening is prolonged by over 58 times, and the fatigue strength FAT corresponding to 106 cycles is increased by about 66％; 2) As for the SS400 butt joint ( single side welding double sides molding) , after being treated by UPT, the nominal S-N curve (m = 10) of FAT 100 MPa(R =0.5) should be used for fatigue design. The standard S-N curves of FAT 100 MPa (R = 0.5, m = 10) could be used for fatigue design of the SS400 steel butt joints treated by ultrasonic peening. 相似文献
15.
16.
N2 and N3 are known as the transition points of the three principal stages of fatigue： initial accommodation, accretion of damage and terminal fatigue. Many experiments show that the ratios of N2/Nf and N3/Nf tend to be stable even though the specific N2 and N3 values may fluctuate widely. The primary goal of this research is to study the piezomagnetic field surrounding AISI 1018 steel specimen under repeated loads and to find the ratio values of N2/Nf and N3/Nf by analyzing 11 sets of low-cycle fatigue data. An MTS-810 testing system with a peak capacity of 222 kN was used to obtain the data which consisted of stress, strain, and piezomagnetic field. A computer program was constructed to track the evolution of the piezomagnetic field and regression analysis was carried out to determine N2 and N3 values. It was observed that there exists a consistent relationship between N2 and Nf. The apparent invariance of the ratio N2/Nf implies that N2 may be identified as an index of performance in the early loading response of a specimen that forecasts its fatigue life, Nf. It has been demonstrated that measurements of the magnetic and mechanical hysteresis can yield significant insights into the various stages of the development of a fatigue critical microstructure which culminates in complete rupture of the material. 相似文献
17.
In this paper, based on the principle of heat transfer and thermal elastic-plastic theory, the heat treatment process optimization scheme for face gears is proposed according to the structural characteristics of the face gear and material properties of 12Cr2Ni4 steel. To simulate the effect of carburizing and quenching process on tooth deformation and residual stress distribution, a heat treatment analysis model of face gears is established, and the microstructure, stress and deformation of face gear teeth changing with time are analyzed. The simulation results show that face gear tooth hardness increases, tooth surface residual compressive stress increases and tooth deformation decreases after heat treatment process optimization. It is beneficial to improving the fatigue strength and performance of face gears. 相似文献
18.
The influence of direct quenching （DQ） on microstructure and mechanical properties of 0.19C-1.7Si-1.0 Mn-0.05Nb steel was studied. The microstructure and mechanical properties of reheat quenched and tempered （RQ＆T） steel plate were compared with those of direct quenched and tempered （DQ＆T） steel plates which were hot rolled at different finish rolling tem-peratures （1173 K and 1123 K）, i.e., recrystallization-controlled-rolled direct-quenched （RCR＆DQ） and controlled-rolled direct-quenched （CR＆DQ）, respectively. The strengths generally increased in the following order： RQ＆T〈RCR＆DQ＆T〈 CR＆DQ＆T. Strength differences between the CR＆DQ＆T and RQ＆T conditions as high as 14% were observed at the tempered temperature of 573 K. The optical microscopy of the CR＆DQ＆T steel showed deformed grains elongated along the rolling direction, while complete equiaxed grains were visible in RQ＆T and RCR＆DQ＆T steels. Transmission electron microscopy （TEM） and electron backscattering diffraction （EBSD） of the DQ steels showed smaller block width and higher density of dislocations. Inheritance of austenite deformation substructure by the martensite and differences in martensite block width were ruled out as major causes for the strength differences between DQ and RQ steels. 相似文献
19.
钢桥面硬沥青浇注式沥青混合料低温性能研究 总被引：6，自引：0，他引：6
通过汉堡轮辙试验 ,考察了浇注式沥青混合料的抗车辙能力 ,硬沥青浇注式沥青混合料具有良好的抗车辙能力 .通过低温弯曲试验和逐步降温的钢桥面铺装复合结构疲劳试验 ,测试与比较了使用硬沥青的浇注式混合料低温抗裂性能 .高性能聚合物改性沥青浇注式混合料具有较长的疲劳寿命和较低的断裂温度 ,可用于钢桥面浇注式沥青铺装 . 相似文献