AZ31镁合金交流脉冲TIG焊接组织与性能研究

采用交流脉冲TIG焊对AZ31镁合金进行焊接,利用光学显微镜及扫描电镜对其焊缝组织进行观察,通过拉伸试验对焊接接头抗拉强度进行测试。结果表明:焊接电流为60A得到的焊接接头成形良好,未出现裂纹,焊缝组织均匀;焊缝主要组织为α-Mg固溶体和β-Mg_(17)Al_(12)沉淀相混合物,沉淀相呈亮白色在晶界处点状析出,分散较为均匀;焊接接头的平均抗拉强为180MPa,达到了母材强度的80%,力学性能良好,可以满足工程构件应用需要。     

浅谈HXN5机车板材矫正工艺及操作技巧

本文通过对HXn5机车板材矫正过程中一些变形原因的分析,总结出板材矫正过程中的操作经验及技巧,从而给出了一些提高产品质量及生产效率的方法。     

无孔型轧制工艺的开发和应用

本文对无孔型轧制技术的开发和应用进行了介绍。无孔型轧制具有节能、降耗、提高生产率的显著效果。     

合金元素对镁合金性能影响

镁合金具有优异的性能,随着关键应用技术的不断发展,其应用潜力巨大。本文简要说明了镁合金的分类,介绍了一些常用合金化元素,如Al、Zn、Mn、Si、Ca、Zr和RE等元素对镁合金性能的影响及机理。这些合金元素单独或共同影响着镁合金组织和性能。     

试论冲压成型工艺在金属板材中的应用

板材成型性能的好坏会直接影响到冲压工艺过程、生产率、产品质量和生产成本.板料的冲压成型性能好,对冲压成型方法的适应性就强,就可以采用简便工艺,高生产率设备,生产出优质低成本的冲压零件.本文简要介绍了金属板材的冲压成型理论和特性,重点介绍了冲压技术的发展水平,同时说明了金属板材的冲压成型性能和未来金属板材成型行业发展的关键.     

热处理对镁合金焊接接头性能的影响研究

综述了热处理对镁合金焊接接头性能的影响研究现状,热处理可以使AZ31B镁合金板的焊接接头的力学性能提高,随着退火温度的升高,AZ31B镁合金搅拌摩擦焊接接头前进侧和后退侧的分界线逐渐消失,热影响区的显微硬度略有下降。热处理可提高AZ31B镁合金板的的抗拉强度和延伸率。     

加工工艺对饲料营养价值及动物生产性能的影响

饲料是畜禽生产上开支最大的一项,在我国饲料支出约占总成本的６５％～７０％,通过恰当的加工方法可以获得较好的经济效益。饲料加工的目的正是为了充分发挥饲料营养价值的潜力,提高产品质量和饲养效果。饲料加工对动物营养的影响一直是饲料加工工艺学家和动物营养学家关心的问题,将加工工艺学和动物营养学有机结合起来能够更大提高动物生产性能。１粉碎粉碎的主要目的是增加饲料接触消化酶的表面积,以使之更易于消化,这也是饲料搅拌、制粒和接受其它处理所必需的。目前许多研究结果表明：粉碎对饲料营养价值和畜禽的生产性能有明显的…     

热处理和变形对镁合金低频阻尼性能的影响及机理研究

基于镁合金所具备的物理属性在热处理以及形变作用下的机理变化作为探究对象,着重对纯镁、Mg-Al系、Mg-Ni系以及Mg-Si系等主要类别进行光学放大观测以及透射显微解析,通过实体面积、环境温度以及振幅频率等三个方面的集中试验,系统全面地探究在热处理以及变形作用下镁合金低频阻尼性能的变化规律、性能演变,从而为镁合金的进一步探究开发创造切实科学的理论基础。     

霉变饲料对肉鸡生长性能、抗氧化性能及组织形态的影响

试验研究霉变饲料对肉鸡生长性能、抗氧化能力及肠道、肝脏、心脏组织形态的影响.选取1日龄艾维因肉鸡180只,随机分为2组,每组6个重复,每个重复15只肉鸡.试验期42d.对照组肉鸡饲喂基础日粮,试验组肉鸡饲喂由自然霉变原料配制的日粮.结果显示,从第2w开始,霉变饲料组肉鸡末重、周采食量、周增重均显著下降(P＜0.05),...     

冷却工艺对70kg级高强钢组织性能影响分析

在相同的成分配比及轧制工艺条件下,对70kg级试验钢进行不同冷却工艺的生产试验,通过轧后钢板金相组织及性能数据结果,研究终冷温度及冷却速率对钢材组织及性能的影响,通过调整控冷工艺实现试验钢板强度及塑性的最佳匹配,确立了批量生产70kg级高强钢的控轧控冷工艺参数。     

锆合金力学性能分析

本文主要通过分析Zr-4合金材料的室温拉伸性能和高温拉伸试验特点,提出利用金属材料拉伸试验方法测量Zr-4合金室温、高温拉伸性能。并通过比较分析锆合金管材在不同温度和应力下的高温拉伸性能试验数据及室温拉伸性能数据,结果表明试验所用Zr-4合金拉伸性能数据集中,误差较小。     

Bioavailability of magnesium in beef cattle fed magnesium oxide or magnesium hydroxide

Two experiments were conducted to compare Mg bioavailability from Mg oxide (MgO) vs Mg hydroxide (Mg(OH)2) fed in either a completely mixed diet or a mineral supplement. In Exp. 1, these Mg sources were incorporated into completely mixed diets and offered to 15 steers (282 kg) allotted to three treatments: control diet containing .19% Mg, control plus .2% added Mg as MgO, or control plus .2% added Mg as Mg(OH)2. Each calf was fed 5 kg/d of the respective diet during 10-d adjustment and 7-d collection periods. Blood samples were collected on d 1, 3 and 7. Mg supplementation increased (P less than .01) fecal and urinary Mg excretions, whereas apparent Mg absorption (%) and retention were similar (P greater than .10) for all treatments. Plasma Mg concentrations were similar (P less than .10) for calves supplemented with MgO and Mg(OH)2 but were higher (P less than .05) for Mg supplemented than for control calves on d 7. In Exp. 2, these Mg sources were incorporated into mineral supplements and offered free choice to 30 spring-calving beef cows gazing tetany-inducing pastures from March 6 to May 1. Each of three groups of 10 cows was assigned to a 5.7-ha tall fescue pasture and offered either a control supplement or a supplement containing 40% MgO or Mg(OH)2. Blood samplers were collected on d 0, 7, 14, 28, 42 and 56. Plasma Mg concentrations were not different (P greater than .10) for cows offered MgO and Mg(OH)2 but were higher (P less than .01) for Mg-supplemented than for control cows on d 28, 42 and 56.(ABSTRACT TRUNCATED AT 250 WORDS)     

Site and extent of apparent magnesium absorption by lambs fed different sources of magnesium

Ten abomasally cannulated crossbred wether lambs (avg wt, 33 kg) were used in a replicated 5 x 5 latin square design to determine the site and extent of apparent absorption of Mg when fed different sources of Mg. Lambs were fed twice daily 220 g of chopped mixed grass hay and 180 g of a corn-based supplement (control; .13% mg, DM basis), or the control diet supplemented with Mg (.26% Mg, DM basis) from MgO, magnesium citrate (MgC), smectite-vermiculite (Mg-Mica) or MgOH. Lambs were maintained in metabolism stalls during each of the five experimental periods. Each period consisted of a 7-d dietary adjustment followed by a 3-d collection of abomasal samples, feces and urine. Abomasal contents were sampled four times daily during the 3-d collection period. The diet contained .5% chromium oxide as a digestion marker. Apparent absorption of Mg was .17, .55, .85, .78 and .82 g/d for lambs fed the control, MgO, MgC, Mg-Mica and MgOH diets, respectively. Apparent absorption of Mg (g/d) was similar (P greater than .05) in the lambs fed the supplemented diets and greater (P less than .05) than in those fed the control diet. Preintestinal absorption of Mg was .21, .57, 1.08, .14 and .92 g/d when the control, MgO, MgC, Mg-Mica and MgOH diets were fed. Lambs fed the control and Mg-Mica diets absorbed similar (P greater than .05) quantities of Mg in the preintestinal region and less (P less than .05) than lambs fed the MgO, MgC and MgOH diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

饲料镁和鲈鱼幼鱼的生长及鱼体镁含量相关性研究

为研究饲料中不同镁含量对鲈鱼(Lateolabrax japonicus)的影响,试验在基础饲料中分别添加0、500、1250、3750、5250、8750 mg/kg MgSO4,配制镁含量分别为167、284、491、959、1327、1759 mg/kg的6种试验饲料,饲养初始体重为(12.31±0.02)g的鲈鱼56 d。结果显示:日粮中适当添加镁显著影响鲈鱼的增重率、特定生长率和饲料效率(P <0.05),其中D4组(镁含量959 mg/kg)鲈鱼的增长率和特定生长率均显著大于其他各组(P <0.05)。饲料镁含量显著影响鲈鱼全鱼水分(P <0.05)。随着饲料镁含量增加,肝脏中天冬氨酸转氨酶(GOT)和丙氨酸转氨酶(GPT)呈下降趋势,GOT与GPT比值和肝脏谷氨酸脱氢酶(GDH)也出现显著变化(P <0.05)。通过回归分析增重率得出,本试验中鲈鱼生长的最适饲料镁含量为846 mg/kg。     

Effects of deficient and adequate dietary magnesium concentrations on body magnesium concentrations in wethers

Effects of 2 dietary Mg concentrations (deficient and adequate: 0.04 and 0.12 g of Mg/100 g of dry matter, respectively) on body fluid and tissue Mg concentrations and performance of wether lambs were evaluated in a 28-day trial. Nine blood and 6 urine samples were collected from each wether. After 28 days, CSF and wool samples were collected, and diet, body fluids, and tissues were analyzed for mineral concentration. Diet effects on serum and urine Mg concentrations were noticed after day 3 (P less than 0.01; P less than 0.05, respectively). Mean serum and urine Mg concentrations for 6 sampling periods were correlated (r = 0.83, P less than 0.001; No. of samples = 12). The effect of dietary Mg on CSF Mg concentrations approached significance (P less than 0.10). Effects of diet on cardiac muscle, liver, and 3rd metatarsal bone Mg contents or hematologic criteria were not observed. Diet affected wool and kidney cortex Mg contents (P less than 0.02). Individual mean 28-day serum Mg concentration was correlated with wool Mg content (r = 0.73, P less than 0.05; n = 8) and with kidney cortex Mg content (r = 0.75, P less than 0.05; n = 8). Wethers fed low Mg diet excreted less urine Ca (P less than 0.001) and had slightly lower serum Ca and K values (P less than 0.10) than did wethers fed high Mg. Significant differences in cardiac muscle, liver, spleen, or kidney cortex Ca contents were not observed. Wethers fed low Mg diet consumed less dry matter and gained less weight (P less than 0.001) than did wethers fed high Mg diet. Body fluid and tissue macromineral concentrations of 1 wether with hypomagnesemic tetany are presented for prognostic and diagnostic purposes.