研究了新型预硬化塑料模具钢DT345经不同工艺热处理后的显微组织及性能。结果表明：通过控制该钢的在线预硬入口温度在850~880℃，出口温度 ≤ 200℃，再经500~530℃回火处理，可使预硬化后的硬度达到40~43 HRC，抗拉强度达到1 140~1 270 MPa，冲击功达到260~270 J，具有适宜的综合性能指标，可满足用户高硬度模具的使用要求。

The microstructure and property of the newly-developed DT345 pre-hardening plastic die steel after different heat treatment processes was studied. The result shows that if on-line pre-hardening inlet temperature is at 850℃ to 880℃, and make outlet temperature is less or equal 200℃ and tempersthrough 500℃ to 530℃, which can make the pre-hardening hardness reaches at 40 HRC to 43 HRC,strengh value achieve 1 140 MPa to1 270 MPa and impact value reach 260 J to 270 J. The new product can meet the user's requirement with high-hardness and all-round performance objective.