Φ100mm自动轧管机组穿孔方头缺陷的产生及消除方法

对Φ１００ｍｍ自动轧管机组穿孔方头缺陷产生的原因进行了分析。方头的形成是由顶杆位置过后，轧辊径向颤动及穿孔变形时椭圆度系数过大等原因造成的。同时提出了相应的解决方法。     

弥散强化铜基复合材料钎焊接头强度

从冶金方面就如何改善Al2O3P颗粒与钎缝的化学相容性及工艺参数对钎焊接头力学性能的影响进行了初步探讨。研究结果表明。当保温时间较短时，由于钎缝中含有较多的Al2O3P颗粒相，且有偏聚的趋势，钎焊接头强度较低；延长保温时间，钎料中活性组元Ti与Al2O3P颗粒反应，可以有效控制Al2O3P含量，从而减缓其不利影响，使钎焊接头强度大幅度提高。     

标准差S在材料疲劳寿命分析中的作用

目前,在评价材料的疲劳强度时,往往只注重比较材料的中值疲劳寿命,而忽略了对数据分散性的比较.事实上,数据分散性,尤其是标准差S在评价材料疲劳性能时非常重要.本文通过对比几组相同试验条件下中国和美国生产的同一铝合金材料的疲劳数据发现:两个产地材料的中值疲劳寿命基本接近,但美国产材料疲劳数据的标准差S小.其对应99.99%存活率的疲劳寿命也明显高于国产材料,这表明标准差大小对高存活率下的疲劳寿命影响很大.因此,应对标准差S给予高度重视.     

Microstructure and strength of brazed joints of TiB2 cermet to TiAl-based alloys

In this study, TiB2 cermet and TiAl-based alloy are vacuum brazed successfully by using Ag-Cu-Ti filler metal.The microstructural analyses indicate that two reaction products, Ti ( Cu, Al ) 2 and Ag bused solid solution ( Ag ( s. s ) ) , are present in the brazing seam, and the iuterface structure of the brazed joint is TiB2/TiB2 Ag ( s. s ) /Ag ( s. s ) Ti ( Cu,Al)2/Ti( Cu, Al)2/TiAl. The experimental results show that the shear strength of the brazed TiB2/TiAl joints decreases us thebrazing time increases at a definite brazing temperature. When the joint is brazed at 1 223 K for 5 min, a joint strength up to 173 MPa is achieved.     

Ceramic coating on ceramic with metallic bond coating

The change in structure and adhesion strength of the interface by heating in air has been investigated for a plasma- sprayed alumina coating on a ceramic substrate with a 50Ni- 50Cr alloy bond coating. A veined structure composed of NiO, NiCr ₂O₄, and NiAl₂O₄ oxides grew from the bond coating into cracks or pores in the top coating and the alumina substrate after heating at 1273 K for 20 h in air. The NiAl₂O₄ spinel may have formed by the oxidization of nickel, which subsequently reacted with the alumina coating or the substrate. The mechanism of the penetration of the spinel oxides into the cracks or pores is not clear. The adhesion strength of the coating is increased to about 15 MPa after heating at 1273 K for 20 h in air, compared to an as- sprayed coating strength of only 1.5 MPa.     

水玻璃加入量对微波硬化砂强度及溃散性影响的试验研究

采用微波加热技术来加热硬化水玻璃砂,对比分析了水玻璃的加入量对砂型试样抗拉强度和残留强度的影响规律。试验结果表明,在539W微波功率加热条件下,水玻璃砂的抗拉强度随着水玻璃加入量的增加而强度上升;在相同微波加热条件下,水玻璃砂的残留强度也随着水玻璃加入量的增多而增大。     

浇注法制备表面复合材料用复合剂的强度表征及测试

用改进后的强度测试仪，检测分析了三种自制复合剂不同温度下的抗弯强度，探讨了复合剂强度的测试方法，结果表明：抗弯强度可用来表征用于浇注法制备金属基复合材料的复合剂强度，抗弯强度越高，铸件浇铸成型率越高。     

淬硬工具钢内圆表面磁性研磨加工实践与研究

磁性磨料研磨是一种较新的光整加工的方法，它是在S、N两极之间加入磁性磨料，磁性磨料吸附在磁极和工件表面上，并沿磁力线方向排列成有一定柔性的“磨料刷”，工件一边旋转，一边做轴向振动，以达到去除表层金属的目的，使工件表面粗糙度大大下降。本文介绍了磁性磨料研磨的加工原理，对工件在磁场中的受力情况进行理论分析。对淬硬工具钢(T8A)工件内圆表面进行磁性磨料研磨的加工试验．得出了不同的磁感应强度，不同加工间隙，以及不同研磨时间对加工表面粗糙度和研磨量的影响；从而得出了优化的磁性磨料研磨的加工参数：磁感应强度B=1．0—1．2T；加工间隙△=1-3mm；研磨时间t=4—5min。     

EFFECT OF BRAZING TIME ON TiC CERMET／IRON JOINT BRAZED WITH Ag-Cu-Zn FILLER METAL

The brazing of TiC cermet to iron was carried out at 1223K for 5-20min using Ag-Cu-Zn filler metal.The formation phase and interface structure of the joints were investigated by electron probe microanalysis(EPMA).scanning electron microscopy(SEM) and X-ray diffraction(XRD).and the joint strength was tested by shearing method.The results showed:there occurred three new formation phases,Cu(s.s),FeNi and Ag(s.s) in TiC cermet/iron joint.The interface structure was expressed as TiC cermet/Cu(s.s) FeNi(Ag(s.s) a little Cu(s.s) a little FeNi/Cu(s.s) FeNi/iron.With brazing time increasing,there appeared highest shear strength of the joints.the value of which was up to 252.2MPa when brazing time was 10min.     

微量Zr对Al-5.8Cu-0.3Mn合金焊接接头组织与性能的影响

采用4047焊丝对Al-5．8Cu-0．3Mn铝合金进行熔化极惰性气体保护焊，利用金相显微镜、透射电镜、显微硬度等检测分析手段研究了Zr对Al-5．8Cu-0．3Mn母材及焊接接头的力学性能和显微组织的影响。结果表明，Al-5．8Cu-0．3Mn合金中添加适量Zr元素可使母材强度提高30MPa，焊接接头强度提高50MPa，同时，细化了母材的再结晶组织和焊缝组织。焊接接头的强度低于母材强度，焊缝区是合金的薄弱处，热影响区强度降低是θ‘相粒子受热粗化所致。