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Abstract:
A set of
formulae of strain-rate ε sensitivity exponent m are deduced from
theories in different typical deforming path by using experimental
parameters F (forming load), v (velocity of cross-head) and l (gauge
length of specimen), through which the uniform method for measuring ml
(strain-rate sensitivity exponent under constant velocity), mv
(strain-rate sensitivity exponent under constant velocity) and mF
(strain-rate sensitivity exponent under fixed load) is established on
experimental curves of constant ε, constant v and fixed F respectively.
ml, mv and mF are measured on the same group of curves of constant ε
(constant v or fixed F) and their results are different, which is shown
that there exists structure sensitivity in super-plastic forming.
Whereas, it should be analyzed why the results of ml, mv and mF are
different, which are measured with the same measuring formulae on
different group of curves under constant ε, constant v and fixed F.
Furthermore the structure sensitivity of m-value is analyzed subtly.
Key words:
Super-plastic tensile forming Strain-rate sensitivity exponent
Experimental parameter
CLC No: TH871
国家自然科学基金资助项目. Received 20000820,
received in revised form 20001117
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