A novel iso-scallop tool-path generation for efficient five-axis machining of free-form surfaces

Weld cladding is a process of depositing a thick layer of a corrosion resistance material over carbon steel plate to improve the corrosion resistance properties. The main problem faced in stainless steel cladding is the selection of process parameters for achieving the required clad bead geometry and its shape relationships. This paper highlights an experimental study carried out to develop mathematical models to predict clad bead geometry and its shape relationships of austenitic stainless steel claddings deposited by gas metal arc welding process. The experiments were conducted based on four-factor, five-level central composite rotatable design with full replication technique. The mathematical models were developed using multiple regression method. The developed models have been checked for their adequacy and significance. The direct and interaction effects of process parameters on clad bead geometry and its shape relationships are presented in graphical form.     

Genetic algorithm based optimization of the process parameters for gas metal arc welding of AISI 904 L stainless steel

The present study is focused on welding of super austenitic stainless steel sheet using gas metal arc welding process with AISI 904 L super austenitic stainless steel with solid wire of 1.2 mm diameter. Based on the Box — Behnken design technique, the experiments are carried out. The input parameters (gas flow rate, voltage, travel speed and wire feed rate) ranges are selected based on the filler wire thickness and base material thickness and the corresponding output variables such as bead width (BW), bead height (BH) and depth of penetration (DP) are measured using optical microscopy. Based on the experimental data, the mathematical models are developed as per regression analysis using Design Expert 7.1 software. An attempt is made to minimize the bead width and bead height and maximize the depth of penetration using genetic algorithm.     

不锈钢堆焊层上细长孔底部修复

针对已完成精加工的不锈钢堆焊密封面上钻孔，将不锈钢堆焊层钻穿，致使与底部低合金钢相通，给耐蚀容器使用带来极大隐患的事故，介绍一种小直径孔底修复工艺，采用填充同材质金属堵，再加自动氩弧焊，使表面自熔熔深大于2 mm的密封焊工艺。该工艺能避免常规的预热，焊后热处理、密封面研磨等修复工序，极大地降低了生产成本，加快生产进度。使用该工艺完成的全部12个螺纹孔底密封焊，经液体渗透检验合格，并通过业主和第三方监造联检验收，孔内螺纹和密封面无一损伤，实现了预期的目标。     

双面超薄不锈钢复合板激光焊接接头组织及耐腐蚀性能

采用同步送粉填充焊的方法,利用Nd:YAG固体脉冲激光对0.1mm+0.8mm+0.1mm不锈钢复合板进行了双面焊双面成形的实验研究。确定了激光焊接双面超薄不锈钢复合板的最佳工艺参数,利用金相显微镜观察分析了焊缝区各区的微观组织特征。结果表明,双面超薄不锈钢复合板填充粉末后激光焊接接头表面成形好,热影响区窄,焊接变形小;焊缝中心为细小的等轴晶,熔合线附近有细晶区,其他区域为柱状晶区,焊缝为残余奥氏体+马氏体+碳化物组织;在硫酸-硫酸铜腐蚀溶液中腐蚀16h后,焊缝表面与腐蚀前没有明显变化,对试板进行180°弯曲试验,未产生晶间腐蚀裂纹。     

液压支架管激光熔覆316L不锈钢涂层组织与性能研究

基于煤机设备在特殊环境下的使用特点, 选择液压支柱管用20钢作为基体材料, 以316L不锈钢作为熔覆材料, 采用高功率半导体光纤耦合激光器在其上进行激光熔覆实验, 并对熔覆后涂层的形貌、 硬度、 耐蚀性以及耐磨性进行研究. 结果表明, 熔覆层与基体呈现出较好的冶金结合, 且并未出现明显裂纹、 孔洞等缺陷;此外, 熔覆层的硬度、 耐蚀性和耐磨性相对基体都有了很大的提高. 根据分析可知, 熔覆层性能的提高是与熔覆过程中显微组织的变化及热影响密切相关的, 熔覆层中的析出相、 硬质颗粒以及合金中的微量元素也对其性能有很大影响. 研究表明316L不锈钢作为一种良好的熔覆材料, 可用于煤机设备液压支架管的激光熔覆修复. 研究以液压设备用零件为对象, 因此对于煤机修复方面有重要的参考价值.     

陶瓷衬垫和药芯焊丝在焊接厚壁复合钢板中的应用

介绍了采用陶瓷衬垫,埋弧机械化焊,药芯焊丝CO2自动焊来焊接16MnR／316L不锈钢复合板的焊接工艺,解决了厚壁不锈钢复合板的焊接和热处理问题;通过检查焊缝的化学成分和力学性能等,证明了该焊接工艺的可行性,并成功应用于生产中。     

不锈钢热丝TIG堆焊缓冷工艺研究

先将不锈钢热丝TIG堆焊后缓冷,然后对不锈钢堆焊层进行无损探伤和力学性能试验,分析焊后缓冷对不锈钢堆焊层物理性能的影响,再从理论上分析焊后缓冷对不锈钢热丝TIG堆焊层中氢含量,证明焊后缓冷不会对堆焊层产生不利影响,且堆焊层中氢含量极少。     

Direct laser cladding of SiC dispersed AISI 316L stainless steel

The present study concerns development of SiC dispersed (5 and 20 wt%) AISI 316L stainless steel metal-matrix composites by direct laser cladding with a high power diode laser and evaluation of its mechanical properties (microhardness and wear resistance). A defect free and homogeneous composite layer is formed under optimum processing condition. The microstructure consists of partially dissociated SiC, Cr₃C₂ and Fe₂Si in grain refined stainless steel matrix. The microhardness of the clad layer increases to a maximum of 340 VHN (for 5% SiC dispersed) and 800 VHN (for 20% SiC dispersed) as compared to 150 VHN of commercially available AISI 316L stainless steel. Direct laser clad SiC dispersed AISI 316L stainless steel has shown an improved wear resistance against diamond surface with a maximum improvement in 20% SiC dispersed AISI 316L stainless steel. The mechanism of wear was predominantly abrasive in nature.     

在用不锈钢复合钢板制压力容器检验与安全等级评定

不锈钢复合钢板所制造的压力容器，其基层主要满足结构的强度和刚度，而复层主要满足耐腐蚀性的要求。对在用不锈钢复合钢板压力容器定期检验中发现的缺陷，应通过检测技术区分其在焊缝中的部位来评定容器安全等级，缺陷若在复层（包括过渡层）焊缝中，如不是裂纹则不影响容器安全等级。     

65Mn钢表面激光熔覆温度场模拟及性能研究

为了探究不同激光熔覆工艺参数对温度场的影响,利用ANSYS软件对激光熔覆温度场进行模拟。在选定工艺参数下,通过激光熔覆技术在65Mn钢表面熔覆Ni60A合金粉,并与镍基焊条电弧焊试验进行对比。对两种熔覆层的显微组织、显微硬度及摩擦磨损性能进行观察和测试。结果表明：激光熔覆温度场的最高温度与激光功率、频率成正比,而与扫描速度成反比。在激光功率580 W,扫描速度100 mm/min,频率4 Hz,脉宽8 ms的工况下,温度场最高温度达到2 092.1℃。激光熔覆层主要由等轴晶、柱状晶组成,而电弧焊覆层组织的晶粒组织粗大,存有大量树枝晶。激光熔覆层晶粒更加致密,组织均匀,强度、塑韧性性能更好。在硬度与耐磨性方面,激光熔覆层硬度平均值为531.24 HV_0.2,电弧焊熔覆层硬度平均值为492.46HV_0.2,且激光熔覆对硬度的提高效果更加显著。激光熔覆层的磨损率为4.9×10^-4 mm³·N^-1·m^-1,是基体的3/5。磨损机理由严重的粘着磨损转变为轻微的磨粒磨...     

不锈钢复合板焊接接头晶间腐蚀失效分析

针对不锈钢复合板焊接接头出现晶间腐蚀裂纹问题,采用光学显微镜、扫描电镜、XRD等技术手段对复合板焊接接头的组织、成分以及相组成进行检测和分析,对焊接工艺规范和热处理制度对焊接接头耐蚀性的影响进行探讨。结果表明,接头焊缝区铁素体含量18．3％,晶粒度9．5级,过渡层焊缝铬的含量9．58％,低于耐蚀性要求;接头产生了σ等硬脆相,这些因素都增大晶间腐蚀敏感性;焊接线能量过大,将降低接头的腐蚀性能;复合板整体消应热处理可以取消。     

爆炸复合钢板的复层中残余应力分布的测定

用改进的盲孔法对一种复合钢板的双相不锈钢00Cr18Ni5Mo3Si2复层中残余应力测试结果表明，复层内存在不均匀的残余应力，复层表面的残余应力较小，约靠近复层与基层的结合面应力越大，最大残余应力可达100MPa以上。该测试结果对复合钢板的选用具有一定的实际意义。     

在A3钢基材上激光熔覆G112合金的组织与性能

应用激光束将镍基合金粉末,熔覆在A₃钢表面上,可以显著改善其抗磨损性能。本文重点论述了该合金激光熔覆层、结合区、基材热影响区的组织结构及其相应的性能。获得结果。(1)G112合金激光熔覆层的显微结构主要为γ-Ni、Ni₃B,CrB、M₁₃(CB)₆的亚共晶结构,其硬度HV_0.1542～649。(2)覆层与基材间的结合带是含有Fe、Ni、Cr等元素的相互扩散带。(3)热影响区的组织主要为先共析铁素体、魏氏组织和少量的索氏体。(4)G112合金激光熔覆层具有优异的抗磨损性能,其相对耐磨性是A₃钢的6—7倍。其磨损机制为粘着磨损、磨粒磨损,疲劳磨损的复合磨损。     

Imperfections in laser clading with powder and wire fillers

Laser cladding has been increasing in laser job shops both for component repair and manufacture. The process is quite mature nowadays, from a scientific approach, but companies need manufacturing guidelines and procedures to minimise the occurrence of defects and improve service quality and productivity. Typical imperfections occurring in laser clads can be divided into two major groups: shape and microstructural defects. The first group includes the contact angle of the clad track with the substrate surface and the total height of the clad including penetration. In the second group are considered lack of fusion, porosity and cracks. It is not clear to which extent the use of powder or wire as filler materials influence defect formation, though it is well known that these are mostly related to material properties and operational procedures. This paper presents the work done in laser cladding using filler wire and powder in real productive environment in job shop cases on different substrates: AISI 316 stainless steel, H13 and P20 tool steels. An overview of the defects that are more prone to appear in these materials is presented and strategies to minimise their occurrence proposed.     

（S32750＋Q345R）不锈钢复合厚钢板热处理工艺研究

制订不锈钢复合钢板的热处理工艺时,既要考虑基板的特点,又要考虑复层的要求,两者相差较大,尤其S32750属超级双相不锈钢,热处理温度及冷却方式与基层Q345R差别较大,如果控制不当,易析出σ相,可导致复合钢板性能不舍,加工时断裂;因此,（S32750＋Q345R）不锈钢复合钢板较常规不锈钢复合钢板的热处理性能更难控制。本文通过试验和生产实践,确定了较厚（S32750＋Q345R）复合钢板的热处理工艺。     

Optimization of experimental temperature measurement in GTAW process by means of DoE technique and computational modeling

The prediction of temperature distribution is a critical process in the study of welding thermal field. Therefore, the accuracy in temperature measurement is quite important to provide meaningful results and to establish the coupling among thermal field results and other studies in welding as mechanical and microstructural analyses. This work deals with statistical analysis and design of experiments (DoE) in order to establish an optimal experimental design for thermal history measurements in welding processes with thermocouples independent of base material. Calculations from theoretical correlations and computational modeling of heat flow were used to accomplish the present study. The Gas Tungsten Arc Welding process (GTAW) was used in the experiments along with plates of a structural steel (ASTM A 36) and a martensitic stainless steel (AISI CrMo 12-1). Four different parameters were studied related with the disposition, separation, depth, thermocouple arrangement and application of thermal paste. An optimal design was able to measure the maximum temperatures in adjacent zones to the weld bead, which are important for the study of welding thermal behavior.     

基于灰色关联分析与自适应混沌差分进化算法的激光熔覆工艺参数优化方法

多道搭接激光熔覆工艺具有复杂性与耦合性,熔覆层质量受到工艺参数的直接影响.为确定最佳的工艺参数,以45钢表面多道搭接激光熔覆M2合金粉末为例,针对工艺参数对熔覆层宽度、表面平整度和稀释率的影响,设计相应的中心复合实验;通过灰色关联分析(GRA)建立熔覆层质量综合评价度,将多目标优化问题转化为单目标,并采用响应面分析法建...     

Development of mathematical models for prediction of weld bead geometry in cladding by flux cored arc welding

The mechanical and corrosion resistant properties of cladded components depend on the clad bead geometries, which in turn are controlled by the process parameters. Therefore it is essential to study the effect of process parameters on the bead geometry to enable effective control of these parameters. The above objective can easily be achieved by developing equations to predict the weld bead dimensions in terms of process parameters. Experiments were conducted to develop models, using a three factor, five level factorial design for 317L flux cored stainless steel wire with IS:2062 structural steel as base plate. The models so developed were checked for their adequacy. Confirmation experiments were also conducted and the results show that the models developed can predict the bead geometries and dilution with reasonable accuracy. It was observed from the investigation that the interactive effect of the process parameters on the bead geometry is significant and cannot be neglected.     

405/Q245R不锈钢复合板焊接工艺及接头组织与性能

分别采用钨极氩弧焊（TIG）、选用ER309L焊丝和焊条电弧焊（SMAW）、选用A302焊条两种不同工艺焊接405/Q245R不锈钢复合板的覆层和过渡层,并采用焊条电弧焊方法、选用E4315焊条焊接其基层。对复合板接头进行力学性能测试,结果表明,接头的抗拉强度接近于母材本身强度,拉伸试样断裂均发生于母材部位;对接头金相组织的观察显示,两种接头的过渡层焊缝组织均为奥氏体加少量铁素体,在过渡层焊缝/基层母材侧界面未发生明显的碳迁移现象;进一步对过渡层焊缝进行XRD测定,未发现接头焊缝中有害相的生成,说明获得接头的性能良好,焊接工艺可行,能够满足工程实际需要。     

不锈钢连铸弯曲段辊系熔覆工艺优化研究

通过对不锈钢连铸弯曲段φ150自由辊修复的熔覆特性分析,提出了对表面耐热合金熔覆修复工艺的改进,使修复辊表面的气孔等缺陷率全面控制,解决硬度不均的问题,避免熔覆过程中热迁移现象,使熔覆表面具有更耐磨、耐高温、耐疲劳及抗腐蚀性能.