船用高强钢薄板焊接成形研究

探究了不同焊接工艺对3 mm船用高强钢薄板焊接成形质量的影响.结果表明:3 mm对接试板经不同方法焊接后均呈马鞍形变化.焊条电弧焊和手工气保焊焊接的试板变形严重,且两者变形量和残余应力基本相当,药芯焊丝CMT(cold metal transfer)自动焊接试板的焊缝内部存在夹渣缺陷.利用实心焊丝CMT自动焊接试板的焊缝均匀、内部无缺陷,焊缝中心残余应力明显降低,其变形量平均值比焊条电弧焊减小37.8%,且线能量仅为焊条电弧焊的22.4%.焊接试板变形量与其线能量大小的变化趋势一致.     

690 MPa级低合金高强钢焊接接头组织性能

为探讨690 MPa级低合金高强钢焊接接头组织与性能的关系,采用手工电弧焊(SMAW)和埋弧焊(SAW)获得成形良好的焊接接头,经过拉伸、冲击、弯曲试验及光学显微镜、扫描电镜和透射电镜分析,对两种焊接方法的接头组织性能进行研究.结果表明:两种焊接方法的焊缝组织主要为板条状贝氏体和少量针状铁素体,粗晶区为粗大贝氏体和少量马氏体;焊缝中含有大量分布均匀的微小球形夹杂物;两种焊接方法所得焊接接头都具有较高力学性能,-50℃的冲击断口形貌为韧窝、准解理混合型;埋弧焊焊缝冲击韧性低于手工电弧焊,手工电弧焊熔合线处冲击吸收功小于埋弧焊,但随距熔合线距离增加其值增加更快.显微组织和夹杂物是影响接头性能的主要因素.     

爆炸焊接参数设计能量模型(I)

论述了建立爆炸焊接参数设计能量模型的依据和方法 ,得到了表征能级分布和能级转换的等能量线和数学表达式 ,阐明了焊接参数的变化规律和等能量线的性质     

粉尘测量仪检定准确性和效率的主要影响因素初探

粉尘测量仪作为监测环境空气受颗粒物污染程度的重要工具,被广泛用于疾控、环保和工矿企业中。为保证其量值的准确可靠,需定期进行计量检定或校准。为了提高其检定或校准的准确性和效率,本文探讨了几个主要影响因素,如检定中仪器放置方式、被检仪器系数设置方式、尘棒质量、发尘控制方式、粉尘浓度稳定时长等。     

对光散射式粉尘测试仪的标定及其不确定度分析

依据JJG846-1993《光散射式数字粉尘测试仪检定规程》,采用KCl气溶胶对光散射式数字粉尘测试仪进行溯源性标定,对该检定规程加以拓展,用多分散气溶胶代替单分散气溶胶,并根据误差传播定律建立不确定度计算的数学模型,以及对测量结果的不确定度进行A类和B类评定,实验结果表明KCl气溶胶发尘稳定,适宜作为实验校准中的标定尘源。     

TC4钛合金激光焊接应力变形有限元分析

基于ANSYS有限元分析软件,采用三维移动热源,对TC4钛合金激光焊接残余应力和变形进行了数值模拟和实验研究.结果表明:钛合金激光焊接产生很大的纵向残余应力,而横向残余应力较小.激光焊接线能量增加时,纵向残余应力拉伸区域变宽,峰值应力降低;而横向残余应力随线能量的增加而升高.在临界焊透规范以上焊接时,随焊接线能量的增大,角变形随之而减小,而横向收缩变形增大.焊件被完全穿透时,线能量对角变形的影响作用降低.钛合金激光焊接变形和残余应力实验结果与数值计算结果吻合性较好.通过焊缝金相实验分析了焊接残余应力和变形与线能量的内在关系.     

线能量对铝/钢双光束激光焊接接头组织及性能的影响

为了研究线能量对铝钢异种金属双光束激光焊接接头组织和性能的影响,本工作通过激光双光束铝钢搭接焊工艺优化实验,获取了焊接工艺窗口,研究了焊接线能量与焊缝成形、显微组织和接头性能的关系.结果表明:不同焊接速度下,线能量过大或过小将导致焊缝出现坑洞或未连接,焊接速度超过0.05 m/s时,线能量的最高值和最低值基本维持不变,且线能量与熔深成正比,与熔宽无相关性.低线能量的焊接接头的抗剪切力为130.70 N/mm,断裂位置位于铝合金焊缝,而高线能量的焊接接头的抗剪切力仅有35.76 N/mm,断裂位置位于铝钢界面焊缝.低线能量接头的显微组织为板条马氏体,显微硬度的最高和最低值分别位于热影响区和焊缝中心,而高线能量接头的显微组织为粗大柱状晶或片状马氏体,显微硬度的最低值位于熔合区.在低线能量和高线能量接头处,主、辅助光束共同作用面积分别占整个焊缝截面积的1/3和2/3.     

X100管线钢焊接接头组织对其断裂性能的影响

通过调整焊接线能量研究了X100管线钢CO2气体保护药芯焊焊接接头的组织及其对维氏显微硬度和断裂韧性(CTOD)的影响规律.结果表明:和15kJ/cm焊接线能量相比,30kJ/cm线能量下焊接接头的显微硬度较低,粗晶区的断裂韧性也较低,其主要原因是30kJ/cmm焊接线能量下组织中的贝氏体含量减小使得材料强度降低.     

SRJ60Fe焊条焊接工艺性研究

利用汉诺威焊接质量分析仪对SRJ60Fe焊条不同焊接电流下的焊接工艺性进行了分析评价,同时对945Fe焊条、ZS60A焊条与SRJ60Fe焊条在相同焊接条件下的焊接工艺性进行对比分析.利用焊接烟尘收集装置对SRJ60Fe焊条和ZS60A焊条的焊接发尘量进行了测量.结果表明,SRJ60Fe焊条的整体焊接工艺性良好,焊接发...     

不同焊接方法对铁路桥梁用321-Q370qE复合板焊接接头疲劳性能的影响

桥面结构焊接的方法主要是埋弧自动焊和焊条电弧焊,为了比较采用不同的焊接方法对321-Q370qE复合板焊接接头疲劳性能的影响,对这两种焊接方法形成的焊接接头进行了疲劳试验.试验结果表明,采用焊条电弧焊形成的焊接接头的抗疲劳性能优于埋弧焊形成的焊接接头.     

炸药量对双层圆管爆炸焊接影响的数值模拟

为研究炸药量对爆炸焊接过程的影响,并优化双层圆管结构爆炸焊接工艺.采用ANSYS/LS-DYNA软件建立钢-铜双层圆管爆炸焊接三维有限元模型,在对模型进行可靠性验证的基础上,研究炸药量对结合界面、覆管所受压力及其运动速度和动能的影响规律.结果表明:炸药量对基覆管产生的变形量及覆管速度影响极大,变形量和覆管速度过小均不能实现良好结合。覆管所受压力及其速度和动能在爆炸瞬间急速增大,与基管碰撞后急速减小并趋近于0,据此可判断爆炸复合管的质量.     

多功能超音速火焰喷涂粒子速度的计算机仿真

超音速火焰喷涂粒子焰流速度对涂层的性能影响极大,但其实际速度很难确定,根据射流动力学原理,建立了多功能超音速火焰喷涂的焰流和粒子速度模型,并对焰流、WC-17Co和NiCrBSi喷涂粒子的速度进行了计算机仿真计算.结果表明:随喷涂距离增大,超音速焰流速度、温度不断下降,直至形成亚音速焰流;粒子的速度分布在300～800...     

超音速电弧喷涂在风机叶轮上的应用

介绍了超音速电弧喷涂技术的基本特点，并分析了该技术在电厂风机叶轮上应用的可行性，同时结合排粉机叶轮制定了具体喷涂工艺，为火电厂排粉机叶轮的防磨损提供一种经济可行的方法。     

Simulation of explosive welding using the Williamsburg equation of state to model low detonation velocity explosives

Explosive welding is a process for producing bi-metallic plates and tubes. Whilst well established it has been essentially an empirical process. In most welding operations, low-speed explosives such as ammonium nitrate fuel oil (ANFO) mixtures, are used. Such explosives have a low velocity of detonation with an appreciable detonation zone. The usual Jones–Wilkins–Lee equation of state (EOS) is not valid. A more representative EOS is the Williamsburg EOS.Recent work to numerically model the process is described. A notable advance is the use of the finite difference engineering package AUTODYN with a Williamsburg-type EOS to model low detonation velocity ANFO explosive and perlite mixtures. In this work, the Williamsburg EOS was coded as a subroutine in the AUTODYN software package which was then used to simulate most aspects of the explosive welding process. The computed results were validated by explosive welding trials.The phenomenon of jetting and the interfacial waves usually observed in explosive welding were successfully reproduced.     

热镀锌生产线大直径工艺辊的堆焊

热镀锌用大直径工艺辊表面涂层易被锌渣压溃,从而划伤带钢表面.由于尺寸原因,目前国内无法对其表面进行淬火.采用表面堆焊硬质材料后再喷涂制备复合涂层可解决这一问题.确定了堆焊材料和焊接工艺,并进行了大直径工艺辊的实物制作,分析了制作过程中存在的问题,指出了今后技术改进的方向.     

Continuous resistance welding of thermoplastic composites: Modelling of heat generation and heat transfer

A process model composed of electrical and heat transfer models was developed to simulate continuous resistance welding of thermoplastic composites. Glass fabric reinforced polyphenylenesulfide welded in a lap-shear configuration with a stainless steel mesh as the heating element was considered for modelling and experimental validation of the numerical results. The welding temperatures predicted by the model showed good agreement with the experimental results. Welding input power and welding speed were found to be the two most important parameters influencing the welding temperature. The contact quality between the electrical connectors and the heating element was found to influence the distribution of the welding temperature transverse to the welding direction. Moreover, the size of the electrical connectors was found to influence the achievable welding speed and required power input for a certain welding temperature.     

Warm spraying—a novel coating process based on high-velocity impact of solid particles

Abstract

In recent years, coating processes based on the impact of high-velocity solid particles such as cold spraying and aerosol deposition have been developed and attracting much industrial attention. A novel coating process called ‘warm spraying’ has been developed, in which coatings are formed by the high-velocity impact of solid powder particles heated to appropriate temperatures below the melting point of the powder material. The advantages of such process are as follows: (1) the critical velocity needed to form a coating can be significantly lowered by heating, (2) the degradation of feedstock powder such as oxidation can be significantly controlled compared with conventional thermal spraying where powder is molten, and (3) various coating structures can be realized from porous to dense ones by controlling the temperature and velocity of the particles. The principles and characteristics of this new process are discussed in light of other existing spray processes such as high-velocity oxy-fuel spraying and cold spraying. The gas dynamics of particle heating and acceleration by the spraying apparatus as well as the high-velocity impact phenomena of powder particles are discussed in detail. Several examples of depositing heat sensitive materials such as titanium, metallic glass, WC–Co cermet and polymers are described with potential industrial applications.     

喷涂参数及带速对大豆蛋白液喷涂平均密度的影响

目的研究大豆蛋白喷涂在硫酸纸上的平均密度,以及喷涂参数和带速对喷涂平均密度的影响。方法首先通过摄像机采集喷涂图像,再运用Matlab软件处理计算大豆蛋白液所占面积比。面积比越大,则大豆蛋白喷涂效果越好,并利用响应面分析法研究喷涂参数及带速对喷涂平均密度的影响。结果当液压为159 Pa,气压为180 Pa,带速为11.93 mm/s时,大豆蛋白液所占面积比可达79.9079%,此时最佳。结论单个因素中液压和带速对喷涂平均密度有显著影响。通过分析软件建立了大豆蛋白液所占面积比与喷涂参数及带速之间的关系模型,并得到了最佳喷涂条件。     

Computer simulation and control of plasma spraying processes

An integrated technological system for modeling, experimental study, and practical realization of plasma spraying process was devised. The system provided simulation of the main plasma spraying process stages (heating and acceleration of particles in a plasma jet, coating structure formation, heat transfer, and stress-strain state in a coating-substrate system); experimental measurement of the main plasma spray characteristics and entering them in a computer in a real time mode; computer control of the spraying process; and plasma spray coating corresponding with the devised technological process.

This integrated system was upon the basis of vacuum plasma spraying “Plasmatechnik” equipment. An original opto-electronic system was used for experimental measurement of temperature, particle velocity, and coating temperature.     

Effect of high filling ratio on the weld strength of hot plate welded calcite filled polypropylene and its comparison with talc filling

In this paper, the effect of the hot plate welding parameters on the weld strength of 40 % calcite filled polypropylene were investigated by utilizing design of experiment and compared to talc filled polypropylene. The plate temperature and the heating time were considered as the process parameters. A mathematical predictive model of the weld strength was developed in terms of welding parameters. The results show that the mathematical model correlates well with the experimental results. The optimum welding parameters of calcite filled polypropylene are determined as 260 °C of plate temperature and heating time of 25 s. The welding strength of the joint welded at optimum parameters is found as 18.32 MPa. Hot plate welding efficiency of the 40 % calcite filled polypropylene is observed to be higher than 40 % talc filled polypropylene material.