首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
王德宝  牟祖茂  杨峥  徐雁  徐辉  宋鑫晶 《轧钢》2021,38(1):74-79
针对热轧板带工作辊在轧制过程中发生的断辊事故,对其失效原因进行了分析。通过对轧辊断口宏观形貌,材质化学成分、显微组织、工作层残余奥氏体含量及断口形貌的分析,认为轧辊断裂属于应力断裂.而造成轧辊断裂的主要原因是工作层残余奥氏体含量过高,轧辊在使用过程中残余奥氏体发生马氏体相变,巨大的内应力导致裂纹的产生;同时轧辊工作层显微组织中网状碳化物,芯部C、Mn含量不足以及铸造孔洞缺陷加速了裂纹扩展而造成的。为此,对轧辊的制造工艺、使用及维护提出了相应的措施,确保了轧辊的正常使用。  相似文献   

2.
热轧型钢轧辊的断裂行为分析及对策   总被引:1,自引:1,他引:0  
吴成军 《锻压技术》2007,32(1):97-99
热轧型钢过程中经常发生轧辊断裂现象,断裂部位主要在轧辊的孔型处、辊颈处及辊颈与辊身交界处.分析了轧辊产生断裂的原因,认为断辊主要是由轧辊材质热处理回火不充分或存在铸造缺陷、轧辊冷却不良及轧制操作不当引起的,并从技术和管理两个方面提出了相应的控制措施.  相似文献   

3.
Φ1300轧辊断裂失效分析   总被引:2,自引:2,他引:0  
某化工公司卷板机轧辊在卷板过程中发生断裂事故,通过宏观微观检测、化学成分分析、金相显微组织分析等手段,对断裂的轧辊进行了失效分析.分析结果表明,轧辊心部的韧性不足是轧辊发生断裂的主要原因,并提出了相应的改进措施.  相似文献   

4.
一、前言轧制6.5mm盘条所用的轧辊,选用瓦房店轴承厂生产的GCr15钢,经锻造成型及轧后球化退火,机械加工成轧辊后,最终淬火加低温回火处理。 1985年4月生产的14个轧辊,经机械加工后进行淬火和低温回火处理时,连续淬裂12个,其中沿轴向断裂成两半或三半的有11个,另一个发现有裂纹。其断裂有的是在淬火过程中断裂的,有的则是回火过程中断裂的。我们对轧辊断裂原因进行了分析研究。二、轧辊生产工艺  相似文献   

5.
本文通过对斜轧轧辊的组织分析,结果表明轧辊断裂的主要原因是H13钢在浇注过程中出现液析碳化物和锻造不充分,并提出解决轧辊断裂的方法。  相似文献   

6.
介绍了热轧带钢轧辊常规使用与维护技术要求,分析轧辊在使用过程中出现的剥落、断裂、裂纹等失效形式的特征及产生原因,并给出了合理的纠正与预防措施,以减小轧辊失效带来的损失.  相似文献   

7.
利用连续流变成形实验机制备断面为5 mm×50 mm的Mg-3Sn-1Mn镁合金型材,研究辊靴型腔中的合金组织及其形成机理。结果表明:合金熔体首先在轧辊和靴子表面异质形核。当轧辊表面比较粗糙时,合金在轧辊表面异质形核能力较强,利于枝晶的形成;在轧辊剪切/冷却作用下,枝晶发生破碎形成自由晶,枝晶破碎主要由枝晶臂剪切断裂机制和枝晶臂熔断机制引起;自由晶在生长过程中,由于合金熔体内部的层流剪切作用,自由晶进一步被破碎,晶粒周围溶质分布趋于均匀,其散热择优方向也不明显,沿各个方向生长机会均等,晶粒以球状晶或等轴晶形式长大。  相似文献   

8.
60CrMoV钢轧辊热处理后断裂分析   总被引:2,自引:1,他引:1  
通过对60CrMoV钢轧辊热处理回火后断裂原因分析得出,轧辊断裂是在热处理残余应力作用下发生脆性断裂,钢中化学成分偏析和非金属夹杂物的聚集分布造成裂纹扩展;轧辊在原工艺基础上增加450 ℃补充回火4 h后没有再出现开裂.  相似文献   

9.
高钒高速钢、高铬铸铁冷轧辊磨损试验研究   总被引:16,自引:0,他引:16  
王强  杨涤心  龙锐  魏世忠 《铸造》2005,54(6):570-574
通过对高钒高速钢、高铬铸铁轧辊试样的冷轧模拟试验研究表明,高钒高速钢由于其均匀分布、形态较好的高硬度碳化物使其耐磨性大幅提高,在同等试验条件下为高铬铸铁试样的4.4倍.微观分析表明,轧辊试样磨损机理主要表现为疲劳剥落,浅层剥落主要表现为棘齿裂纹的萌生、扩展与断裂的过程;高铬铸铁轧辊试样深层失效主要表现为MC3型碳化物的断裂并形成裂纹源并在疲劳循环过程中断裂失效,高钒高速钢轧辊试样MC型碳化物有少量破碎并形成晶间裂纹源,主要失效方式表现为碳化物颗粒剥落,并对此进行了定性的力学解释.  相似文献   

10.
用于热轧F5机架上材质为高镍铬球芯的上工作辊在使用过程中辊身发生断裂,断辊事故的原因是轧辊内部存在显微疏松冶金缺陷,在工作中轧辊受到扭转应力和热应力的综合作用,在疏松部位产生应力集中,在疏松部位裂纹形核,并在长期的交变应力作用下不断扩展,直至轧辊整体断裂。为此,提出了防止断辊事故的具体对策和改进措施。  相似文献   

11.
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.  相似文献   

12.
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.  相似文献   

13.
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.  相似文献   

14.
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.  相似文献   

15.
The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).  相似文献   

16.
The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.  相似文献   

17.
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.  相似文献   

18.
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.  相似文献   

19.
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.  相似文献   

20.
韩磊 《腐蚀与防护》2015,36(1):84-90,94
综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号