Ta1/0Cr18Ni9薄板储能焊熔核高熵化机理

针对钽与钢之间物化性质差异大，焊接时易产生脆性金属间化合物而导致熔焊接头性能低下及裂纹等问题，按照熔核金属高熵化技术思路，利用基于密度泛函理论的热力学第一性原理设计出新型中间层合金Ta₂₀Fe₂₀Ni₂₀Cr₂₀Co₂₀，结合熔合比得到适用于钽/钢储能焊中间层合金成分为Ta₇Ni₃₂Cr₁₉Co₄₂. 采用真空电弧炉熔制纽扣合金锭，继而使用单辊急冷法制备出中间合金箔材，将其用于Ta1/0Cr18Ni9薄板的储能焊连接. 结果表明，在储能焊条件下，Ta1/Ta₇Ni₃₂Cr₁₉Co₄₂/0Cr18Ni9搭接接头形成形貌规则、完整，长径约0.8 mm的扁球形熔核，熔核整体向钢侧发生了偏移. 熔核组织由简单的FCC固溶体组成，无金属间化合物析出，具有典型的高熵合金特征，实现了熔核金属高熵化. 在焊接电压1 000 V，电容500 μF，电极压力30 N下，Ta1/Ta₇Ni₃₂Cr₁₉Co₄₂/0Cr18Ni9储能焊接头平均强度可达到395 MPa.     

基于高熵合金中间层的TA2与Q235电阻焊研究

本文针对钛和低碳钢焊接时易产生金属间化合物导致性能下降及裂纹等问题,采用焊缝高熵化技术路线,设计出TA2／Q235焊接用高熵合金中间层成分,应用急冷快速凝固装置制备出厚约60um、宽约4mm的Ti5Fe5Al30Ni30Cu30和Ti10Fe10Cr5Ni35Cu40高熵合金箔带,并将其用于TA2／Q235的电阻点焊。分析了焊接工艺参数与接头组织的相关性,研究结果表明,一定条件下应用Ti10Fe10Cr5Ni35Cu40中间层较Ti5Fe5A130Ni30Cu30中间层更易实现钛与钢的焊接。在焊接电流为5000～6000A,电极力为5000N,焊接时间为0．6s条件下,应用Ti10Fe10Cr5Ni35Cu40高熵合金中间层获得了TA2／O235的连接,焊缝组织细小均匀,焊缝与母材的结合区未出现金属间化合物迹象。     

急冷条件下Cu-Sn合金的快速枝晶生长

研究快速凝固Cu-xSn（x=7％，13．5％，质量分数）合金的相结构、组织形态和枝晶生长特性，将金属熔体热传导方程与Navier-Stokes方程相耦合，从理论上计算液态合金的冷却速率。结果表明：在急冷快速凝固条件下，Cu-7％Sn合金形成过饱和的单相α-Cu固溶体组织：Cu-13．5％Sn合金形成以亚稳的Cu137Sn相为主相、α-Cu为第二相的快速凝固组织：随着冷却速率的增大，溶质截留效应增强，合金相结构由复相向单相转变；沿垂直于辊面方向上合金的组织形态依次为近辊面细小等轴晶、中部柱状晶及自由面粗大等轴晶：增大冷却速率，晶体形态由柱状晶向等轴晶转变：在急冷快速凝固过程中，α-Cu和Cu137Sn相均以枝晶方式生长；随温度梯度的增大，晶体生长速率呈线性增大。     

铸铁件电弧冷焊熔合区白口组织的控制

进行了冷焊条件下控制铸铁件焊补区白口组织的试验．结果表明，采用Ｓｉ－Ｃａ－Ａｌ－Ｂｉ系合金粉层对焊补熔合区进行集中强石墨化孕育处理及焊前在缺陷表面形成Ｎｉ基合金粉末喷涂层，均可消除熔合区白口     

细直径YG5FA硬质合金/45Cr钢储能焊工艺分析

应用微型储能焊机对1.5 mm超细颗粒硬质合金YG5FA和45Cr合金钢进行对焊,研究了结合界面的结构特征、组织形态及结合机制,分析了焊接参数对接头质量的影响.结果表明,储能焊能够实现超细颗粒硬质合金的快速凝固焊接,有效防止界面反应,获得的焊接接头组织细小致密,硬质合金组织无粗化迹象.裂纹是硬质合金储能焊接头的主要缺陷,具有典型的脆断特征和延迟特性.焊后进行350 ℃保温30 min的去应力处理,即可有效地预防裂纹的产生.     

Role of temperature gradient in liquid／solid phase solution-diffusion bonding

The liquid-film solution-diffusion bonding of ZCuBe2. 5 alloys was conducted using Cu-based alloy powders. The tensile strength of the joint is up to 318 MPa. With the increase of temperature gradient, the bonding time decreases and the interlace migration velocity increases remarkably. The appropriate temperature gradient is 5 -40 K/cm. Under fixed bonding time, the thickness of diffusion layer increases with the increase of temperature gradient, and this tendency becomes more remarkable with the prolonging of bonding time.     

多元微合经铸铁气焊丝的研究与应用

通过加入Ca、Ni、Ti、Bi多元复合合金,研制出灰铸铁和球墨铸铁两种气焊丝;焊接试验及生产实践证明,两种焊丝在冷焊条件下所形成的焊缝强度、硬度和颜色均与母材具有良好的一致性;可满足有性能的重要球铁和灰铁铸件加工面的修复,经济效益显著。     

奥氏体不锈钢储能焊接头组织形成规律

采用微型储能焊机对厚度为 0.2mm 的 0Cr18Ni9 奥氏体不锈钢薄板进行了点焊连接研究,理论分析了微型熔核的温度场和冷却速率.结果表明,微型接头由熔核区和熔合区组成.极短的焊接时间,高的冷却速率 5.1×106 K/s,使得熔核中奥氏体组织来不及长大,熔核凝固组织得到显著细化,具有快速凝固特征;同时,熔核中奥氏体组织在敏化温度区停留时间很短,抑制了铬在奥氏体晶界上的析出.当储能焊接电压为 80V、电容为 6600μF、电极力为 18N 时,可获得综合性能优良的高质量点焊接头.

Abstract：

The 0Cr18Ni9 austenitic stainless steel sheet with 0.2 mm thickness was welded in capacitor discharge spot welding.The temperature field and cooling rate of nugget was calculated. The results show that the joint microstructure consists of nugget zone and semi-melt zone. Due to very short time in welding, the cooling rate of the joint reaches to 5.1×106 K/s, the growth of austenite microstructure is impeded, and the microstructure of the nugget is refined,which has rapidly solidified characteristics. As the austenite microstructure of the nugget stays in temperature province of activation with very short time, the chrome of austenite grain boundary precipitations is checked. To obtain the high quality spot-weld joint, the welding parameters are determined as: welding voltage 80 V, capacitor 6 600μF and electrode pressure 18 N.     

急冷Cu-Sn合金箔快速凝固连接工艺

应用微型电容储能焊机对厚度约40～60μm的急冷Cu-Sn合金箔带进行了快速凝固焊接,分析了焊接工艺参数对接头组织与性能的影响.结果表明,在储能电容不变的条件下,焊接电压及电极力对接头抗剪强度有着显著影响.随着锡含量增加,实现合金箔焊接所需要的电压减小,电极力增大.Cu-7%Sn,Cu-13.5%Sn合金箔比较适宜的焊接工艺参数分别为U=90 V,F=11 N及U=85 V,F=11.5 N.气孔是Cu-Sn合金箔主要焊接缺陷.随电压降低或电极力增加,接头冷却速率增大,气相形核率降低,气泡长大、合并和迁移在一定程度上受到抑制,气孔产生降低.

Abstract：

The rapid solidification welding of quenched Cu-Sn alloy foils with the thickness of 40 - 60μm was conducted by a micro-type capacitor discharge welding machine, and the effects of welding parameters on microstructural morphology and mechanical properties of joint were researched. The results indicate that welding voltage and electrode pressure have obvious influence on the shear strength of joint under fixed capacitance. With the increase of Sn content, the welding voltage needed decreases and electrode pressure rises accordingly. The favorable welding parameters are U = 90 V, F=11 N for Cu-7% Sn alloy and U = 85 V, F = 11.5 N for Cu-13.5% Sn alloy. The main welding defect is porosity. With decreasing of welding voltage and increasing of electrode pressure, the joint cooling rate increases and the pore nucleation rate decreases. Meanwhile, the growth, mergence and migration of porosities are suppressed, resulting in the decrease of porosity forming tendency.     

工艺因素对球铁中奥氏体枝晶数量和形态的影响

采用着色腐蚀法显示出球墨铸铁中的奥氏体枝晶,研究了碳当量、浇注温度、壁厚及含硅量对球墨铸铁中奥氏体枝晶数量和形态的影响。结果表明：碳当量减少．枝晶数量增多,形态趋于发达;壁厚减小,枝晶数量增多,形态变得发达;浇注温度提高,枝晶数量减少而形态变得粗壮,不发达;含量增加,枝晶数量减少。