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利用碳在马氏体与奥氏体之间的扩散分配实现钢的组织结构与力学性能调控,是近年来钢铁材料领域的重要研究方向。基于碳的完全均匀分配,Speer提出了淬火-分配(Q-P)热处理工艺,本文总结了近年Q-P工艺碳分配机理研究和工艺实践。同时,根据碳在奥氏体和马氏体中的扩散分配过程分析,提出了碳的梯度扩散分配与控制理念,并开发出了分级-淬火-分配(S-Q-P)工艺,希望能获得低碳马氏体、残留奥氏体、高碳马氏体相间分布的组织。对35SiMn钢分别进行淬火-回火(Q-T)、Q-P及S-Q-P工艺试验,并测量力学性能及观察显微组织。结果表明,S-Q-P工艺处理后钢的强塑性积达到31.2 GPa%(1240 MPa×25%),比传统Q-T和现行Q-P工艺分别提高67%和32%,其显微组织也接近于工艺设计的理想组织,证明了利用碳的梯度扩散分配可以实现对钢的组织与性能的调控。
The use of carbon in martensite and austenite diffusion distribution between the steel structure and mechanical properties of steel regulation, is an important research field in the field of steel materials in recent years. Speer proposed a quenching-distribution (Q-P) heat treatment process based on the complete and even distribution of carbon. This paper summarizes the carbon allocation mechanism and process practice of Q-P process in recent years. At the same time, based on the analysis of diffusion and distribution process of carbon in austenite and martensite, the concept of gradient diffusion distribution and control of carbon was put forward and a classification-quenching-distribution (SQP) process was developed. Martensite, retained austenite, high-carbon martensite phase distribution of the organization. The 35SiMn steel was quenched and tempered (Q-T), Q-P and S-Q-P process test, and the mechanical properties were measured and the microstructure was observed. The results show that the strength of the steel reaches 31.2 GPa% (1240 MPa × 25%) after SQP treatment, which is 67% and 32% higher than the traditional QT and current QP respectively. The microstructure is also close to the ideal of process design Organization, proved that the use of gradient diffusion of carbon distribution can be achieved on the organization and performance of steel regulation.