單項(xiàng)選擇題

對(duì)于沒有明顯屈服階段的塑性材料，通常以S_0.2表示屈服極限。其定義有以下四個(gè)結(jié)論，正確的是哪一個(gè)？（）

A.產(chǎn)生2%的塑性應(yīng)變所對(duì)應(yīng)的應(yīng)力值作為屈服極限
B.產(chǎn)生0.02%的塑性應(yīng)變所對(duì)應(yīng)的應(yīng)力值作為屈服極限
C.產(chǎn)生0.2%的塑性應(yīng)變所對(duì)應(yīng)的應(yīng)力值作為屈服極限
D.產(chǎn)生0.2%的應(yīng)變所對(duì)應(yīng)的應(yīng)力值作為屈服極限