Size Effect of Elongation Ratio of 18Ni(250) Steel

The elongation ratio of 18Ni(250) steel is low in actual test.When the steel is as thin as 1.4mm, the elongation ratio of it is only at 4%around,as if its plasticity is very bad and it approaches brittle materials. Series tensile test were carried out to find the reason for lower elongation ratio of the steel with different thickness 18Ni(250) steel plate as samples.The results show that 18Ni(250) steel has a size effect phenomena,that is its elongation ratio decreased with the decrease of the sectional dimension of the tensile samples.The plasticity of this steel is very fine in fact,and the plasticity of it reflected by its elongation ratio is a feint.