小特集「硬さ試験」
微小球反発硬さeNM1A10試験法と試験機の開発
キーワード:
Hardness,
Rebound hardness,
Small ball rebound hardness,
eNM3A10,
Standard blocks for hardness
2024 年 69 巻 1 号 p. 9-12
詳細
2024 年 69 巻 1 号 p. 9-12
To reduce errors in rebound hardness due to mass effects, the eNM3A10small ball rebound hardness test method and a testing machine has been developed. In this test method, an alumina ceramic ball indenter with a diameter of3mm is used alone to impact a specimen at a velocity of V1＝10m／s.
The rebound velocity V2of the indenter from the specimen is measured to obtain the coefficient of restitution e＝V2／V1, which is then taken as the hardness value of the specimen.
We have developed a new tester, eNM1A10, with an alumina ceramic ball with a diameter of1mm,which is1／3of the ball of eNM3A10, in order to reduce the minimum thickness of the sample.
The eNM1A10tester was then tested on the hardness standard blocks of e＝0.63and0.86(≒300HV and700HV)so on , and the test results were in good agreement with those of the eNM3A10，confirming the success of the prototype development of eNM1A10.
