Evaluation of Formability of Light Metal Sheets at High Temperatures by Conical Cup and Erichsen Tests

摘要

Experimental methods to evaluate theformability of sheet metals at a high, uniformtemperature have not been established. Conicalcupping and Erichsen tests were carried out using aself-constructed apparatus in which a blank sheet, dieand punch were heated uniformly at temperatures between293 and 573K. Five kinds of fully annealed light metalsheets of 0.8mm thickness were used as the testmaterials: 1100, 3004, 5052 aluminum alloys, AZ31magnesium alloy and commercial pure titanium. Tensilestrength, total elongation, strain hardening exponentand Lankford value were obtained by tensile tests atvarious testing temperatures. The conical cup valuesof aluminum alloy sheets were not markedly affected bytest temperature, while the Erichsen values of aluminumalloy sheets increased with increasing temperature.Thus, stretch formability of aluminum alloy sheets ismore dependent on the testing temperature than is thedeep drawability. The AZ31 magnesium sheet showed poorconical cup and Erichsen values at room temperature,but appreciable improvement of both values was observedwith increasing test temperature. The formability ofa pure titanium sheet was relatively high at roomtemperature and the temperature dependence offormability was essentially the same as that of themagnesium alloy sheet. The correlation betweenErichsen values and total elongation was stronger thanthat between conical cup values and total elongation.