Sally had a 2000mm width, 4000mm long and 5mm in thickness aluminum AA1050 alloy strip. She needed this strip to be in thickness of 1mm. So, she has designed a process for 1mm aluminum sheet production out of AA1050 alloy. First, she has cold rolled the 10mm strip down to 5mm then she made a tensile test and has seen that the tensile strength of the 5mm sheet has 1000 N/m². What is the concept in this question?