新型时效硬化塑料模具钢的开发

发布时间：2018-01-21 15:57

  本文关键词： 塑料模具钢 NAK80钢 NAK80-M钢 固溶处理 时效处理　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着塑料制品的应用越来越广泛,塑料制品的种类愈加多样化,表面质量要求不断提高,从而对塑料模具钢的抛光性能要求越来越高,同时还对塑料模具钢的耐腐蚀性提出了新的要求。目前市场上广泛使用的高镜面抛光性能塑料模具钢是日本开发的NAK80时效硬化型预硬化塑料模具钢。但国内自主生产的NAK80钢存在较大差距,对该钢的生产关键技术未掌握,存在心部力学性能差、组织分布不均匀、淬透性不佳等问题,同时,该钢耐蚀性能较差,不能满足塑料制品发展对模具钢的耐蚀性要求。调制开发具备更优异力学性能和耐蚀性能的新型时效硬化型塑料模具钢具有重要意义。本文在NAK80钢的基础上,通过调整合金成分与优化热处理制度,研发出新型时效硬化型塑料模具钢NAK80-M。与NAK80钢相比,NAK80-M钢中添加了 2.00%的Cr和0.15%的V,Mo的含量提高至0.76%,Ni和Cu的含量分别降低至1.50%和0.49%。通过研究合金元素变化对相组成和相变行为、微观组织和力学性能、以及热处理工艺的影响,得到以下主要结论:(1)热力学计算与等温转变试验结果表明,NAK80-M和NAK80两种钢的平衡相种类相同,但NAK80-M试验钢的临界温度点Ac3、Ac1相对较高,使得碳化物的溶解温度提高。(2)固溶处理后,NAK80和NAK80-M试验钢获得的组织主要由板条马氏体和残余残余奥氏体构成。分别在850℃和880℃下进行2h的固溶处理,NAK80和NAK80-M钢可获得最高的硬度。同时,对两种钢的峰值硬度进行比较,可知NAK80-M钢的硬度更高。(3)固溶+时效处理后,NAK80和NAK80-M试验钢获得的组织主要由板条马氏体、粒状贝氏体、残余奥氏体和析出碳化物构成。不同时效温度的研究表明,NAK80-M钢在880℃固溶2h后空冷,随后进行540℃时效,达到材料力学性能峰值,NAK80钢在850℃达到材料力学性能峰值。不同时效时间研究表明,NAK80-M钢在880℃固溶2h后空冷,随后进行540℃时效保温4h后空冷,达到材料力学性能峰值。同时对比两种钢力学性能峰值数据可知,NAK80-M钢的硬度和冲击韧性值比NAK80钢高出2.5HRC和50J。NAK80-M钢的最佳热处理工艺是:880℃固溶2h后空冷,随后进行540℃时效保温4h后空冷。
[Abstract]:With the more and more extensive application of plastic products, the variety of plastic products is becoming more and more diversified, and the surface quality requirements are constantly improved, so the polishing performance of plastic die steel is required more and more. At the same time, new requirements for corrosion resistance of plastic die steel are put forward. The high mirror polishing performance plastic die steel widely used in the market at present is a NAK80 aging hardening prehardening plastic die steel developed by Japan. There is a big gap in domestic NAK80 steel. The key technology of production of the steel is not mastered, there are some problems such as poor mechanical properties of the center, uneven distribution of microstructure and poor hardenability. At the same time, the corrosion resistance of the steel is poor. It is of great significance to develop a new aging hardening plastic die steel with better mechanical properties and corrosion resistance. This paper is based on NAK80 steel. On the basis. By adjusting the alloy composition and optimizing the heat treatment system, a new aging hardening plastic die steel NAK80-M.Compared with NAK80 steel was developed. The content of 2.00% Cr and 0.15% V Mo in NAK80-M steel was increased to 0.76%. The contents of Ni and Cu were reduced to 1.50% and 0.49.The effects of the change of alloy elements on the phase composition, phase transformation behavior, microstructure and mechanical properties, as well as the heat treatment process were studied. The results of thermodynamic calculation and isothermal transformation test show that the equilibrium phases of NAK80-M and NAK80 steels are the same. However, the critical temperature point of NAK80-M test steel is relatively high, which makes the dissolution temperature of carbides increase. 2) after solution treatment. The microstructure obtained from NAK80 and NAK80-M test steels was mainly composed of lath martensite and residual austenite, and the solution was treated at 850 鈩，

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