Idling noise from circular saws made of metals with different damping capacities

Circular saw construction using materials with high internal damping has been found to be an effective way to suppress whistling noise during saw idling. A high-damping alloy called Silentalloy (12Cr-3Al-Fe) was previously shown to be an effective material for this purpose. Tests with Silentalloy suggested that a logarithmic decrement of at least 0.07 is needed. Silentalloy does have some disadvantages, such as modest strength, difficult heat treatability, and special order status. The purpose of these experiments was to confirm the general applicability of the minimum effective logarithmic decrement of 0.07 and to find more practical metals for saw-blade construction. Three commercially available metals of different damping capacity were selected. The idling noises of saws made of these metals were compared with those of saws made of typical saw steel and Silentalloy. The minimum logarithmic decrement for whistling-noise suppression was found to be approximately 0.01. On a logarithmic scale, this value is similar to the 0.07 value previously found for a Silentalloy saw. A ferromagnetic steel (20Cr-3A1-Fe) was found to be a useful alternative to Silentalloy from the viewpoint of strength, but the cost of this steel makes it unsuitable for mass production. The success in identifying an effective alternative material to Silentalloy provides encouragement for the identification of other high-damping alloys among the 13Cr-Fe to 18Cr-Fe series without the cost disadvantage of ferromagnetic steel.     

硝酸法处理废钨铜合金回收钨和铜新方法

对采用硝酸法从废钨铜合金中回收金属钨和铜，以及转化有害的氮氧化物的方法进行了探讨．并设计了数种较小规模的回收装置．经实验表明，本法具有操作简便、投资省、能耗低、污染小等特点，具有一定的实用价值．     

Effect of Yttrium on Morphologies of Precipitation Phases Along Grain Boundary of As-cast ZK60 Magnesium Alloy

Morphologies of precipitation phases along grain boundary of the as-cast Mg-6.0Zn-0.45Zr, Mg-6.0Zn-(1.2Y) and Mg-6.0Zn-0.6Zr-1.0Y alloys are studied by using the methodologies of metallurgical phase analysis, scanning electron microscopy(SEM) analysis and energy diffraction x-ray(EDX) analysis. The experimental result indicates that the main precipitation phases along grain boundary of the as-cast alloys Mg-6.0Zn-0.45Zr is Mg-Zn binary phase. There are two kinds of precipitation phases along grain boundary for Mg-6.0Zn-1.2Y and Mg-6.0Zn-(0.6)Zr-1.0Y alloys. One grew at triangular grain boundary, which is fish-bone -like and contained Mg-Zn binary phase and Mg-Zn-Y ternary phase. The other distributed mainly around the grain, which is net-like and contained Mg-Zn-Y ternary phase. In addition, there are lots of granular phases, extending to the interior of the grain, at the rim of grain boundary phases. Finally, Y can intensively change morphology of precipitation phases along grain boundary of the as-cast Mg-Zn-Zr alloy (ZK60) alloys.     

An Optimization Model and Its Computer Software System for Regulation of Alloy Elements During Steelmaking Process

In this paper, an optimization model is designed for regulating alloy elements during steelmaking process, and a real-time computer software system has been developed based on the characteristics of alloy steelmaking. The results indicate that the system is of good operation performance, remarkable economical benefits and higher application value.     

新型槽楔合金CuNiCrSi合金时效析出与时效相变动力曲线研究

利用示差量热扫描仪研究了新型汽轮发电机转子槽楔合金CuNiCrSi合金加热过程中的相变过程。通过不同时效处理的合金导电率计算时效相变动力学可知:时效析出分2个温度段,在低温阶段,时效早期通过调幅方式形成溶质原子富集区,然后在溶质富集区发生失稳有序化,最后生成δ-Ni2Si相;而在高温阶段,合金可以不经过调幅过程而直接以形核长大方式析出δ-Ni2Si相。