Volume 32, Issue 4 (July 2004)
Mechanical Property Evaluation Using the Small Punch Test
The small punch (SP) test technique is an attractive method for evaluating mechanical behavior in materials where only small volumes of materials are available. An SP-test machine was developed where miniature disc specimens 5 and 3 mm in diameter and with thickness ranging between 50 to 400 µm can be investigated. For two materials, a 1Cr-0.5Mo low alloy steel and an 18Cr-9Ni austenitic stainless steel, the stress-strain flow curve was assessed and compared with that in tensile tests. The yield strength was determined from the SP-test by analyzing the initial elastic deformation with help of classical plate bending theory. The effective flow properties in the biaxial stress state were evaluated through analytical modelling of the stretching deformation. Good agreement between the uniaxial and biaxial flow properties was found for the 1Cr-0.5Mo steel and acceptable agreement for the 18Cr-9Ni steel.