GCr15轴承钢激光表面熔凝强化的研究

本文研究了 GCr15轴承钢经激光表面熔凝处理后显微组织的变化,讨论了激光表面熔凝的强化机理。激光表面熔凝强化的本质是马氏体的孪晶强化,残余奥氏体的形变强化、碳的固溶强化及枝晶细化强化等。     

2Cr13钢激光表面合金化的组织和性能分析

2Cr13钢通过激光表面合金化达到表面改性的目的。利用扫描电镜观察了在不同工艺参数下，激光表面合金化的强化效果及显微组织。用显微硬度计检测了激光合金化组织的显微硬度。结果表明，2Gr13钢激光表面合金化能大大提高其表面的硬度和耐磨性，使它的应用更为广泛。     

铸钢件表面铸渗合金化试验研究及应用

通过对各组成比例不同的合金涂料进行试验,研究各种涂料对铸件表面质量和合金化层组织的影响,从中选择合理的配比,并应用于破碎机机锤。生产试验结果表明,经表现合金化的破碎机机锤磨耗明显低于未经表现合金化的破碎机锤;合金涂料的配比是铸件表面合金人技术的关键。     

Pr激光表面合金化提高Ti－6Al－4V抗氧化性

采用激光Ｐｒ合金化表面处理，研究了Ｔｉ合金的高温氧比行为，结果表明，加入Ｐｒ改变了氧化膜结构，抑制了氧的短路扩散，并改善膜的附着性和塑性，氧化速度显著下降．     

Pr激光表面合金化提高Ti—6Al—4V抗氧化性

采用激光Ｐｒ合金化表面处理，研究了Ｔｉ合金的高温氧化行为，结果表明，加入Ｐｒ改变了氧化膜结构，抑制了氧的短路扩散，并改善膜的附着性和塑性，氧化速度显示下降。     

Mo的表面脉冲激光氮化

激光脉冲辐照置于氮气中的Ｍｏ使表面形成含γ－Ｍｏ２Ｎ的氮化层，激光使Ｍｏ表面熔化导致液相氮化反应，用ＳＥＭ、ＸＲＤ和ＡＵＧＥＲ谱分析表征了氮化层，激光在表层相起的加热和激波效应还有使表层微观组织致密的作用。     

AN INVESTIGATION INTO THE EXPLOSIVE PERFORATION OF MILD STEEL SHEET

Experiments are described in which mild steel plates of 1/10; in. thickness were set on hardened and ground flat steel dies having central square-shouldered round holes, of diameter ranging from 1/10; to 1£ in., and subjected to the shock wave resulting from the detonation of an underwater high explosive charge. Graphical results are presented showing the variation of the deformation of the plates due to cupping and to shear, with increasing charge size, and with varying hole diameter.

Results from records of the pressure wave arising from the detonation of the charge are provided, and attempts are made to correlate these with the predictions of established empirical formulae.     

含硫添加剂含量对电铸镍沉积层组织和性能的影响

研究了硫酸盐镍电镀液的组成及浓度,特别是糖精添加剂含量对电铸镍沉积层组织形貌和性能的影响.结果表明:电镀液中加入适量糖精可显著提高镍沉积层的硬度和强度,同时沉积层可保持较高的韧性;但过高的糖精含量则会促进大量硫化物夹杂的形成、析出和偏聚,造成镍沉积层在强度升高的同时,脆性也开始明显增大.     

GCr15钢表面脉冲激光氮化研究

利用Nd：YAG固体脉冲激光对GCr15钢样品表面进行了激光氮化处理,获得了高硬度、高耐磨损、表面致密均匀的氮化铁改性层,并对改性层进行了XRD谱分析和表面及剖面显微形貌分析、表面硬度及硬化深度和磨损率等的测量。同时对GCr15钢表面激光氮化机理进行了分析和研究。     

基于人工神经网络-遗传算法的1Cr18Ni9Ti钢激光表面熔凝工艺优化

采用激光表面熔凝对1Cr18Ni9Ti奥氏体不锈钢进行改善表面耐蚀性能的处理、研究了工艺参数与腐蚀性能之间的实验关系在此基础上，应用人工神经网络－遗传算法优化激光表面处理工艺.结果表明，神经网络结合遗传算法是材料激光加工工艺优化一种有效而简单的手段.     

LASER SURFACE TREATMENTS FOR PROMOTING CORROSION RESISTANCE OF A CARBON STEEL

The effect of laser treatment and laser alloying on corrosion resistance of 1045 steel has been studied. Various ways of surface alloying have been investigated by using continuous CO₂ laser beam: i) irradiation of chromium painted surfaces; ii) irradiation of Ni and Cr-electroplated surfaces; iii) direct injection of Ni and Cr powders into the melt pool. A high and uniform level of alloying in the surface layer can be achieved in the cases of electroplated surfaces and direct powder injection. It requires, however, an appropriate choice of irradiation conditions (such as beam power, beam traverse speed, beam defocusing and degree of overlapping) that provide remelted layer of a limited and fairly uniform thickness. It has been found that in order to achieve corrosion behavior of laser treated surfaces similar to that of austenite type 304 stainless steel chromium and nickel contents in the alloyed layer are to be higher than those of 304 steel.     

激光表面重熔对高速钢显微组织的影响

采用CO_2连续波激光对W18Cr4V高速钢进行表面重熔处理。分析结果表明,经激光重熔后高速钢的显微组织明显细化,重熔层内的相构成为马氏体、奥氏体,过剩的δ铁素体和M_6C、M_(23)C_6型碳化物。枝晶内为孪晶马氏体和部分板条马氏体。枝晶间为富合金元素的奥氏体和M_6C碳化物,孪晶马氏体上沿孪晶面有M_(23)C_6碳化物共格析出。激光扫描速度增加、δ铁素体量增多,重熔层显微硬度下降。     

用于大平板测量的激光平面度仪

“激光平面度仪”是以空间自动安平的激光面作基准．以光电测头自动跟踪被测面．通过计算机控制和数据处理及输出的新型几何面型测量仪器。该仪器的研制成功,解决了平面测量过程“统一基准测量”这个国标难题;使得几何面型测量实现高精度智能化,并能带加工中心实现面型“光控加工”．论文对仪器工作原理、主要部件设计、仪器精度进行了分述和计算．     

TORSIONAL FATIGUE OF A MEDIUM CARBON STEEL CONTAINING AN INITIAL SMALL SURFACE CRACK INTRODUCED BY TENSION–COMPRESSION FATIGUE: CRACK BRANCHING,NON-PROPAGATION AND FATIGUE LIMIT

In order to examine the threshold condition for the fatigue limit of materials containing a small crack under cyclic torsion, reversed torsional fatigue tests were carried out on 0.47% C steel specimens containing an initial small crack. Initial small semi-elliptical cracks ranging from 200 to 1000 μm in length were introduced by the preliminary tension–compression fatigue tests using specimens containing holes of 40 μm diameter. The threshold condition for the fatigue limit of the specimens containing artificial small defects under rotating bending and cyclic torsion are also reviewed. Crack growth behaviour from an initial crack was investigated. The torsional fatigue limit for a semi-elliptical small crack is determined by the threshold condition for non-propagation of Mode I branched cracks. The torsional fatigue limit of specimens containing an initial small crack can be successfully predicted by the extended application of the √area parameter model in combination with the σ_θmax criterion.     

EFFECT OF LASER SURFACE TREATMENT ON HIGH CYCLE FATIGUE OF AISI 316L STAINLESS STEEL

Abstract— The effect of a laser surface treatment on the high-cycle fatigue behaviour of the austenitic stainless steel AISI 316L was investigated. The specimens were subjected to a surface melting using a CO₂-laser. Although this treatment introduced tensile residual stresses in the melted and resolidified surface layer and intensified the surface roughness, the fatigue limit could be increased by 20% with respect to the as-received specimens. It is suggested that grain refinement in the rapidly resolidified surface layer is mainly responsible for this improvement.     

PRODUCTION OF Cu-Cr ALLOYS BY IN SITU REDUCTION OF CHROMIUM OXIDE DURING ELECTRO SLAG CRUCIBLE MELTING (ESCM)

An electro slag crucible melting process for production of copper-chromium alloys is described. The process uses fine copper scrap as a raw material. After the copper scrap is melted, chromium is alloyed with copper by direct reduction of chromium oxide added to the slag. Carbon and aluminum can be used as reductants and the reduction is carried out in situ in the molten slag. Copper chromium ingots containing up to ∼1 wt % chromium were produced by this process. The process serves the dual purpose of recycling copper scrap and alloying remelted copper by chromium. This is the first time that direct reduction has been employed during an electro slag melting process. The in situ reduction technique described has the potential of being a production route for a variety of alloys. It is particularly suitable for production of difficult-to-melt alloys such as copper-chromium.     

铁合金表面激光熔凝一步制备复合生物陶瓷涂层

在经过渡层预处理的TC4钛合金表面上预置设定配比的CaHPO4·2H2O、CaCO3混合粉末，比较少量Y2O3粉末对合成与涂覆生物陶瓷涂层的影响经优化激光工艺处理后，成功地实现一步激光束合成与涂覆生物陶瓷涂层该涂层具有优良的力学性能，且改善了植入材料弹性模量与生物硬组织的匹配性Y2O3对生物陶瓷涂层的合成及性能改善均有重要作用。     

钛合金表面激光熔凝一步制备复合生物陶瓷涂层

在经过渡层预处理的ＴＣ４钛合金表面上预置设定配比的ＣａＨＰＯ４·２Ｈ２Ｏ、ＣａＣＯ３混合粉末，比较少量Ｙ２Ｏ３粉末对合成与涂覆生物陶瓷涂层的影响。经优化激光工艺处理后，成功地实现了一步激光束合成与涂覆生物陶瓷涂层。该涂层具有优良的力学性能，且改善了值入材料弹性模量与生物硬组织的匹配性。Ｙ２Ｏ３对生物陶瓷涂层的合成及性能改善均有重要作用。     

镀锌钢板受热变色的原因分析

用体视显微镜和电镜研究了空调机内部铜管在钎焊过程中镀锌端板发生黑、白变色的原因.结果表明,镀锌板局部变色是钎焊火焰加热而形成Ze-Fe合金所致.黑色区域表面存在细小裂纹,在盐雾实验时表现出低的抗蚀性能.     

SENSITIVITY ANALYSIS OF PROCESSING PARAMETERS BY DIRECT DIFFERENTIATION METHOD FOR LASER SURFACE HARDENING TREATMENT

The present study deals with an application of the finite element method to the sensitivity analysis of processing parameters for laser surface hardening treatment. Computing the sensitivity of temperature distributions to changes in processing parameters allows one to determine the more effective input parameters for laser surface hardening treatment. The interesting processing parameters are taken as the characteristic beam radius (r_b and the laser scan velocity (v). A state equation governing the heat flow in laser surface treatment is analyzed using a three-dimensional finite element method. The response sensitivities of the temperature T versus r_b and v distributions were obtained using a direct differentiation method. To verify the numerical analysis results, hardened layer dimensions of the numerical analysis are compared with experimental results.