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在本文中,采用GCr15钢,以680和730℃的温度,0.8×10~(-2),1×10~(-2),1.2×10~(-2)和2×10~(-2)min~(-1)的应变速率进行拉伸试验,对于超塑性流动方程式δ=kε~m 中的m 和k 值随应变(δ)发生的变化进行了研究,获得了各试验条件下的m-δ关系曲线(或m-δ-C 关系曲线。C-((k_0+dk_0)/k_0))。求得了各试验条件下的m_(?)和m_F 值。肯定了GCr 15钢存在和试棒的起始应变δ(=0.00%),拉伸期间各阶段的应变δ_1(δ_(11),δ_(12),δ_(13)……),拉断时的总延伸率δ_(?)相对应的m_0(≠0),m_1(m_(11),m_(12),m_(13)……),m_(?)值和k_(?)(≠0),k_1(k_(11),k_(12),k_(13)……,),k_(?)值[1]。C_1(C_(11),C_(12),C(13)……)=(k_1(k_(11),k_(12),k_(13)……)/k_9,C_F=k_F/k_(?),其相互关系可由L。Q·m-δ方程式(或L.Q.m-δ-C 方程式)表达[2,3]:δ_I(%)=[C_(?)ε~(m_I-m_(?))-1]×100(拉伸过程中)或δ_F(%)=[C_Fε(m_F-m(?))-1]×100(试棒拉断时)在全部情况中,除一例(730℃,ε=2×10~(-2)min~(-1))外,m 值都随应变(δ)的增大而减小,直到断裂为止。此时存在C_I=C_F=1(或k_0=k_1(k_(11),k_(12),k_(13),……)=k_F)的简单情况[2,3],问题得到简化。所进行的理论曲线和实测数据的比较是令人满意的。在730℃,ε=2×10~(-2)min~(-1)的条件下,m-δ关系曲线表现为先快速上升,然后缓慢下降,直到断裂为止。将和m 峰值对应的应变量称为“极限应变量”。对于曲线上各点C 值(C_(?)和C_F)进行了计算。C-δ关系为近似的直线。直线的斜率在“极限应变”处发生突然变化
In this paper, GCr15 steel was used to heat the steel at temperatures of 680 and 730 ℃, 0.8 × 10 ~ (-2), 1 × 10 ~ (-2), 1.2 × 10 ~ (-2) and 2 × 10 ~ ) min ~ (-1), the changes of m and k in the superplastic flow equation δ = kε-m with strain (δ) were studied. The results obtained under different experimental conditions m-δ curve (or m-δ-C curve .C - ((k_0 + dk_0) / k_0)). The m_ (?) And m_F values were obtained under each test condition. The initial strain δ (= 0.00%) and the strain δ_1 (δ_ (11), δ_ (12), δ_ (13) (≠ 0), m_1 (m_ (11), m_ (12), m_ (13)), m_ (?) And k_ (?) Corresponding to the total elongation δ_ ), k_1 (k_ (11), k_ (12), k_ (13) ...), k_ (?) value [1]. C_1 C_11, C_12, C13 = k_1 k_11, k_12, k_13 / k_9, C_F = k_F / k_ ), The correlation between them can be expressed by L.Q · m-δ equation (or LQm-δ-C equation) [2,3]: δ_I (%) = [C_ (?) Ε ~ (m_I_m_ (?)) -1] × 100 (during stretching) or δ_F (%) = [C_Fε (m_F-m (?)) -1] × 100 (when the test bar is pulled off) In all cases, ε = 2 × 10 ~ (-2) min ~ (-1)), the value of m decreases with the increase of strain (δ) until it breaks, at which point C_I = C_F = 1 (or k_0 = The problem is simplified in the simple case of k_1 (k_ (11), k_ (12), k_ (13), ...) = k_F. The comparison between the theoretical curve and the measured data is satisfactory The relationship curve of m-δ showed a rapid increase at 730 ℃ and ε = 2 × 10 ~ (-2) min ~ (-1), and then slowly decreased until it was broken, which corresponded with the peak value of m Is called the “ultimate strain.” The C values (C_ (?) And C_F) for each point on the curve are calculated. The C-δ relationship is an approximated straight line. The slope of the line suddenly abruptly changes at the “ultimate strain” Variety