用开缺口冲击标样校验冲击机的必要性和有效性--全国冲击试验能力验证结果分析

叙述了发达国家和国际标准化组织对冲击试验机校验及对校验用冲击标样的要求,指出发达国家采用高度纯净和均匀的40CrNiMo钢制作开缺口的冲击标样,成本高,限制了发展中国家大量采用这种标样.提出并用热轧低碳钢板研制成开缺口内控冲击标样,变异系数<3%,且成本低廉,在实际应用中,特别是在2001年中国实验室能力验证委员会组织的冲击试验能力验证工作中,这种试样对于验证冲击机的精度是有效的,证明定期采用开缺口冲击标样校验冲击机是必要的.同时提出,为了有效校验冲击机的精度,至少必须采用一组数量不少于两只冲击功预期值相同的冲击标样.

THE ATTESTATION ON VALIDITY AND NECESSITY FOR USING REFERENCE TEST PIECES TO CALIBRATE CHARPY IMPACT MACHINES

It is required by developed countries and ISO that Charpy impact machines have been calibrated annually with reference test pieces which coefficient of variations is within 5%. Developed countries use 40CrNiMo steel, which is made by special manufacture processes for very pure and very uniform as raw material to produce reference test pieces. The high cost embarrasses developing countries to use this kind of reference test pieces widely. A production method of low cost reference test piece which coefficient of variation is within 3% by hot rolled low carbon steel sheet is developed. The test pieces have used in Baoshan Iron & Steel Co. Ltd., laboratories and have showed efficiency on finding problems for impact machines, however attestation of validity on this reference test piece for calibration Charpy impact machines in large number of laboratories is needed. In 2001, CNACL national laboratory ability on Charpy impact validation campaign not only prove the validity of the low cost reference test piece, but also attest indirectly that it is necessary to calibrate Charpy impact machines by reference test pieces annually. At the same time, it is foud that to calibrate impact machine is necessary to use at least two reference test piece with same reference energy range.