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为了研究Mg处理对钢中夹杂物的影响,采用NiMg合金对铝脱氧30CrNi2MoVA钢进行处理。共进行了3组试验,终点钢中Mg的质量分数分别小于0.001%、0.010%、0.014%。试验结果表明:Mg处理可以起到良好的脱氧、脱硫、脱磷效果,能有效地使钢中夹杂物弥散细小化,同时改变夹杂物的种类和成分。随着Mg含量逐渐增加,钢中夹杂物的平均等效直径由[?2.0×10-6 m]降低至[?1.0×10-6 m,]钢中等效直径小于[?1.5×10-6 m]的夹杂物比例从84.04%提高到93.65%。但当Mg质量分数增加到0.014%时,钢中开始出现少量的大尺寸夹杂物。将试验结果结合热力学计算分析可知,随着钢中Mg含量的逐渐提高,钢中夹杂物种类由Al2O3依次向Al-Mg-O系、MgO和Mg-O-S系转变。当钢中Mg含量进一步增加时,钢中出现细小的单纯MgS和Mg-O-S-P系夹杂物。 相似文献
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前不久,中国装备制造业龙头中联重科产品全新涂装发布会在长沙麓谷工业园隆重举行.代表着中联重科极致思维的全新涂装主题色——星耀灰、砂砾灰、极光绿,惊艳亮相、华丽登场,吹响了中联重科向高端智能服务型制造业转型升级的号角.
中国工程机械工业协会会长祁俊、湖南省经信委副主任殷林波与中联重科董事长(CEO)詹纯新等见证了这一重要时刻. 相似文献
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铸造生铁价格不断上升,中小铸造厂竞争对手越来越多,利润微薄。某厂利用机加工所产生的铁屑代替大部分铸造生铁投炉,铸件抗拉强度气可达240M.Pa以上,用以生产变速箱壳体,每吨降低生产成本600元左右。 相似文献
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对刚玉-莫来石基质在1550~1700℃烧成4 h,研究其α-Al2O3添加量对刚玉-莫来石基质性能的影响规律.研究结果表明,刚玉-莫来石基质是通过液态SiO2和原料中SiO2与α-Al2O3反应生产的莫来石相进行致密,1650℃是基质的烧成温度转折点,超过此温度,莫来石相发生分解形成无定性SiO2,将影响基质的结构及性能.基质的体积密度和强度随烧成温度和α-Al2O3添加量的增加而增大,并高于刚玉-莫来石窑具材料.随着α-Al2O3添加量的增加,基质的主要断裂方式由穿晶断裂向沿晶断裂方式转变.基质的抗热震性能随烧成温度和α-Al2O3添加量的增加而降低,烧成温度和α-Al2O3添加量是基质抗热震性能主要影响因素. 相似文献
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建立了线架的三维有限元实体模型,并运用ANSYS有限元分析软件对其进行了模态分析,得出了线架的前五阶固有频率和振型。通过分析线架的各阶振动模态的特点,对其进行动态特性分析以及改善结构设计,从而达到线架的优化设计、缩短开发周期和投资成本的预期效果。 相似文献
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When cutting metallic materials, the magnitude and the variation of the amplitude of the cutting force and the quality of the treated surface are of major importance. During the fine turning of alloys that have similar mechanical properties, differences will show both in the roughness of the machined surface and in the magnitude of the cutting forces measured, which can be attributed to the influence of the microstructure of the workpiece material.This paper deals with the influence of the microstructure of Al alloys containing different amounts of silicon on the variation of the amplitude of the signal of the dynamic component of the main cutting force during fine turning. An analysis of the energy spectra and the auto-correlation functions of the amplitude of the dynamic component of the cutting force confirmed the relationship between the latter and the size of the phases in the microstructure of the workpiece material. It was confirmed that the microstructural changes were directly related to the amplitude of the cutting-force variation in the cutting zone. The microstructural changes and the cutting force can be considered as random phenomena; therefore, they may be described by statistical parameters such as the mean value, the standard deviation, and the coefficient of variation. The values calculated for the individual alloys differed considerably and confirmed a close relationship between the statistical values of the intercept lengths of the phases in the microstructure and the dynamic component of the cutting force. 相似文献
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Based on the phenomenological crystallographic theory of martensitic transformations, the following crystallographic characteristics of the tetragonal martensite in high-carbon steel have been calculated: orientation relationships between the crystal lattices of the bct martensite and fcc austenite; the magnitude and direction of the macroscopic shear; the habit plane; the angle and the axis of rotation of the crystal lattice of the martensite. The calculation was performed for three variants of lattice deformation: Bain deformation; two-shear Kurdjumov-Sachs deformation; and the deformation we suggested upon the analysis of the fcc-bcc transformation. In the last variant, a minimum rotation of the crystal lattice of martensite is required; consequently, this variant is closest to the real mechanism of the martensitic transformation. An expression has been derived that describes the interrelation between the degree of tetragonality of the crystal lattice of martensite and the magnitude of the shear deformation of the lattice. It has been shown that the 12 crystal-lographically equivalent variants of shear upon the formation of the lattice of the tetragonal martensite form three groups in each of which the martensite has the same tetragonality axis. For each variant of the shear, we have two equivalent variants of deformation of the martensite with invariant lattice. This results in 24 variants of orientation relationships. 相似文献
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数值模拟技术在汽车覆盖件成形中的应用 总被引:31,自引:18,他引:13
金属薄板成形的数值模拟技术在汽车覆盖件生产及其模具设计制造中起着十分重要的作用。数值模拟技术的广泛应用可以帮助模具设计人员显著地减少模具开发时间、试模周期和费用。为此,详细介绍了应用Dynaform软件模拟覆盖件成形过程的一般步骤,并以某汽车覆盖件的拉深为例,对其成形过程进行了数值仿真。通过对模具零件的运动、板料的成形,以及板料厚度的变化,应力应变分布,成形极限预测等结果的分析,进一步弄清了板料形状,压料筋布置以及压边力大小等工艺参数对汽车覆盖件质量的影响。在案例分析的基础上,针对覆盖件坯料拉深过程中可能出现的起皱现象,给出了相应的拉深工艺优化和模具方案优化。 相似文献
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A.D. Razmyshlyayev M.V. Mironova S.V. Yarmonov P.A. Vydmysh 《Welding International》2013,27(4):296-300
Physical modelling of arc welding with a wire shows that the flow speed of liquid metal, directed into the tail part of the pool and induced by the constant transverse magnetic field, increases with the increase of current and the transverse component of induction of the field. Experimental results show that the distribution of the flows is determined by the distribution of the density component of the current spreading in the liquid metal of the weld pool. The results can be used in the determination of the optimum frequency of the transverse magnetic field for controlling the dimensions of the penetration zone of the metal and the process of solidification of the weld pool metal in arc surfacing and welding. 相似文献
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Study on heat efficiency of laser-TIG double-side welding 总被引:1,自引:0,他引:1
A series of laser-TIG double-side welding experiments for aluminum alloys were carried out to investigate the heat efficiency of the process. The melting efficiency was introduced to evaluate quantitatively the degree of the mutual effect of the laser and the arc. The results showed that the melting efficiency of laser-TIG double-side welding exceeded the sum of the laser and the arc taken separately. With the increase of heat input, the weld depth and melting efficiency of the laser and the arc were increased signifwantly. This, in fact, implies the strong mutual effect of the laser and the arc as heat sources joined simultaneously in the process. Comparatively, the higher efficiency of the laser constituent of heat sources plays the main role in the increase of the process efficiency. The phenomena of arc column convergence, increased laser absorptivity and the formation of heat accumulation region are the causes of the improvement of heat efficiency. 相似文献
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对厚板HQ785T1低合金高强钢填充HS-70焊丝激光—电弧复合焊接头根部化学成分分析及元素线扫描分析,结果表明,焊缝部位主要元素的含量介于母材和焊丝之间,焊缝从上部到根部,随着深度的增加,焊缝元素组成越接近母材,根部焊缝组成以母材成分为主,焊丝成分所占比例较小;焊缝根部冲击韧性低于焊缝上部, 增大坡口钝边,焊缝根部的冲击韧性降低;金相显示根部焊缝中心组织为粒状贝氏体组织,随着钝边尺寸的增加,碳化物析出量减少,组织略显粗大,组织脆性增加. 相似文献
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为了验证Ar-N2混合气体对焊缝中各元素含量和焊缝铁素体数(FN值)的影响,对SS304L奥氏体不锈钢进行了4种比例的Ar-N2混合气体GTAW多层多道焊接试验,研究了4种Ar-N2比例对焊缝金属中各元素含量的影响,以及每条焊缝中各元素含量随着焊道层数的变化趋势。结果表明,不同保护气体类型的11种焊缝化学元素中,只有N元素随着保护气体中氮气比例的升高而明显增加,其它元素则没有明显的影响;经过汇总分析,认为由于稀释率的原因,导致各元素含量在同一保护气体焊缝中的规律为:C元素含量随着层数的增加而下降;Si,P,S和Nb元素含量随着层数的增加无明显上升或下降趋势;Mn,Ni,Cr,Mo和Cu元素含量随着层数的增加而上升;而N元素在纯氩气保护SG-A时的含量随着层数的增加而稍微下降,在SG-AN-0.5,SG-AN-1,SG-AN-1.5 3种保护气体中N元素含量随着层数的增加而上升;分析结果也表明,Creq/Nieq值和FN值有相同的变化趋势,都与氮气含量呈现反比关系。
创新点: 采用了阶梯式的多层多道焊,保留了各层焊缝的原始信息,验证了GTAW焊接方法在保护气体中添加氮气对奥氏体不锈钢焊缝各种化学元素成分的影响,为Ar-N2混合气体GTAW焊接奥氏体不锈钢在工程中的应用提供了可参考的试验数据。 相似文献
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The present paper describes the effect of the half apex angle of the cone-frustum on the motion trajectory under simultaneous five-axis motion and the effect of the sensitive direction of the ball bar when the motion trajectory is measured along the three-dimensional circular conical path. In the present paper, simulation of the measurement by means of a ball bar instrument is mainly conducted using a motion simulator developed previously. In particular, a precise mathematical model was developed to express the pitch errors of the axes of rotation of the five-axis machining center having a tilting rotary table driven by worm gears. In the experiment and simulation, primarily the center position and half apex angle of the cone-frustum were varied. In addition, two sensitive directions of the ball bar were investigated. The motion simulator incorporating the pitch error model can express the detailed trajectories obtained by the ball bar, even if the half apex angle and center position of the cone-frustum and the sensitive direction of the ball bar were changed. Then, the influence of the frictional force of the linear axes of motion, and the backlash and pitch error of the axes of rotation on the circular trajectories were analyzed. In particular, for the case of a half apex angle of 45°, the trajectory due to the errors of the axis of rotation is strongly affected by the sensitive direction of the ball bar. 相似文献