The effects of process temperatures for warm stamping, such as annealing (T_ann), austenitizing (T_aus), and stamping temperatures (T_s), on the tensile properties of Nb-bearing medium-Mn (5.9 wt pct) steel were investigated. The cold-rolled tensile specimens were first annealed at 650 °C to 750 °C, austenitized at 650 °C to 900 °C, held at T_s (500 °C to 700 °C), and then air-cooled to room temperature. Of the three process temperatures, only T_aus significantly influenced the tensile properties of medium-Mn steel; in the T_aus range of 650 °C to 900 °C, the amount of variation in yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) were 555 MPa, 570 MPa, and 20 pct, respectively. Particularly, when the specimens were austenitized at 730 °C to 790 °C, high YS (1060 to 1100 MPa), UTS (1760 to 1795 MPa), and TE (10.0 to 11.7 pct) were obtained due to fine-grained martensite embedded with nano-sized Nb carbides. The Nb-bearing medium-Mn specimen was successfully warm-stamped into a T-part of a B-pillar prototype at 600 °C without any cracks after austenitized at 750 °C for 5 minutes, and then air-cooled to room temperature. The warm-stamped Nb-bearing medium-Mn steel revealed the higher TE (~ 9.3 pct) than the hot-stamped 30MnB5 steel (5.3 pct) at the similar level of UTS (1855 to 1900 MPa).

中文翻译：

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工艺温度对温压含铌中锰钢组织和拉伸性能的影响

研究了热冲压的工艺温度，如退火（T _ann），奥氏体化（T _aus）和冲压温度（T _s）对含Nb的中锰（5.9 wt pct）钢的拉伸性能的影响。 。冷轧拉伸试样首先在650°C至750°C退火，在650°C至900°C奥氏体化，保持在T _s（500°C至700°C），然后空冷至室温。在这三个过程温度中，只有T _aus显着影响中锰钢的拉伸性能。在Ť _AUS在650℃至900℃的温度范围内，屈服强度（YS），极限拉伸强度（UTS）和总伸长率（TE）的变化量分别为555MPa，570MPa和20pct。尤其是，当样品在730°C至790°C的温度下奥氏体化时，由于嵌入了细晶粒的马氏体，因此获得了较高的YS（1060至1100 MPa），UTS（1760至1795 MPa）和TE（10.0至11.7 pct）具有纳米级的Nb碳化物。将含Nb的中Mn试样在750°C下奥氏体化5分钟后，在600°C下成功地热压成B柱原型的T部分，没有任何裂纹，然后空冷至室温。在UTS相似的水平（1855至1900 MPa）下，热压含铌中锰钢的热变形系数（〜9.3 pct）比热压30MnB5钢（5.3 pct）高。