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Non-destructive Detection of a Sintered Tool Material by Impact Repetition

通过重复冲击对烧结工具材料进行无损检测

基本信息

批准号：
60550084
负责人：
SHIRAKASHI Takahiro
金额：
$ 1.28万
依托单位：
Tokyo Institute of Technology, Dept. of Mech. Engg. Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550084/
关键词：
Sintered tool material Tool failure Impact deterioration Ultra-sound wave 非破壊試験

项目摘要

In order to predict tool failure, the fracture characteristics of tool material and their behaviors with impact repetition are required. In recent years, many kinds of sintered tool materials come on the stage because of their excellent characteristics, such as high hardness under high temperature and low frictinal coefficient. The fracture characteristics and their change with impact repetition are required for the prediction of tool failure, but an extreme lot of specimen should be prepared bacause of the scatter of their fracture stresses. The object of the project is a development of non-destructive detection method of fracture stress and its change ---deterioration--- with impact repetition. The results from the project are as follows:1. In order to study the deterioration mechanism of a sintered tool material, the impact testing machine is specially designed, by the machine the fracture and deterioration test may be possible under wide temperature and impact duration range. 2. The mechanism of deterioration is considered as the generation of small crack with random direction around hard particles. 3. A change of a characteristics of ultra-sound wave propagation with impact repetion in sintered tool material is next discussed. An attenuation of wave propagation, especially that of shear wave, is greatly affected by the deterioration level, while a change of velocity of the propagation is not seen in both of lateral and ghear waves. 4. A scatter of fracture stress, which is the defference of the structure in the material, may also be detected by the characteristics of the wave propagation.

为了预测刀具的失效，需要了解刀具材料的断裂特性及其在冲击载荷作用下的行为。近年来，各种烧结刀具材料以其高温下高硬度、低摩擦系数等优良特性而被广泛应用。预测刀具失效需要掌握其断裂特征及其随冲击次数的变化，但由于其断裂应力分散，需要制备大量的试样。本课题的目标是开发一种无损检测断裂应力及其随冲击重复的变化-劣化的方法。本项目的主要成果如下：1.为了研究烧结刀具材料的劣化机理，专门设计了一台冲击试验机，可在较宽的温度和冲击时间范围内进行断裂和劣化试验。2.其失效机理是在硬质颗粒周围产生方向随机的小裂纹。3.接着讨论了超声波在烧结工具材料中的传播特性随冲击重复的变化。劣化程度对波传播的衰减影响很大，特别是横波的衰减，而横波和横波的传播速度变化不大。4.断裂应力的分散，即材料中结构的差异，也可以通过波传播的特性来检测。