热处理工艺对Cr13型塑料模具钢组织与耐蚀性影响研究

发布时间：2019-04-22 07:51

【摘要】：Cr13型马氏体不锈钢因具有较高的硬度和较强的耐腐蚀性能,已成为主要的耐蚀性塑料模具材料,并已用于制造高端、精密注塑模具。热处理工艺不仅对马氏体耐蚀塑料模具钢的力学性能有重要影响,还将影响其耐点蚀性能。因此,研究热处理工艺对Cr13型塑料模具钢耐点蚀性能的影响规律对提高注塑模具的使用寿命有重大意义。本论文以国产30Cr13和进口Stavax ESR钢为研究材料,采用先进材料分析技术研究了不同热处理工艺对Cr13型塑料模具钢的显微组织演变的影响,并利用电化学实验方法分析研究了不同热处理工艺对Cr13型塑料模具钢的耐蚀性影响规律。研究结果表明,淬火态Cr13型塑料模具钢的耐点蚀性能随着奥氏体化温度的提高而提高。降低淬火后存留于Cr13型塑料模具钢基体中的富Cr未溶M_(23)C_6碳化物的含量有利于提高该类型塑料模具钢的耐点蚀性能。另外,提高钢材洁净度,降低钢中TiN夹杂物含量,有利于提高Cr13型塑料模具钢的耐点蚀性能。300℃回火后,Cr13型塑料模具钢基体析出Cr含量与基体相近的M3C型回火碳化物,由于碳化物/基体界面的畸变所导致的内应力而使材料的点蚀电位小幅度降低。在500℃回火时,该类钢基体中有大量富Cr纳米级M_(23)C_6相析出,碳化物/基体界面处由于出现贫Cr区而成为点蚀起始的敏感区域,且碳化物颗粒间距极小,极大地破坏了Cr13型塑料模具钢表面连续性钝化膜的形成,使其在腐蚀性环境中由于失去钝化而耐蚀性急剧降低。回火温度提高至650℃后,Cr13型塑料模具钢基体中析出大量富Cr的微米尺寸M_(23)C_6碳化物,该类M_(23)C_6碳化物晶粒间距较大,因而650℃回火试样依然保持钝化特性,但其点蚀电位明显低于淬火态和300℃回火试样。“淬火-配分(QP)”热处理工艺可使Cr13型塑料模具钢中含有一定量残余奥氏体,并抑制了M_(23)C_6碳化物的析出,从而提高了Cr13型塑料模具钢的耐点蚀性能,使该类塑料模具钢不出现“失钝”现象。当QP处理的Cr13型塑料模具钢的残余奥氏体含量在8 vol.%~10 vol.%时,残余奥氏体在钢基体中主要以薄膜状分布于马氏体板条间,此时Cr13型塑料模具钢的点蚀电位较高,与淬火态钢相近。而当残余奥氏体含量低于6 vol.%和高于13 vol.%时,QP处理的Cr13型塑料模具钢的耐点蚀性能较低,与350~450℃回火试样处于相近水平。
[Abstract]:Due to its high hardness and corrosion resistance, Cr13 martensite stainless steel has become the main corrosion-resistant plastic mold material, and has been used in the manufacture of high-end, precision injection molds. Heat treatment not only has an important effect on the mechanical properties of martensite corrosion resistant plastic die steel, but also affects the pitting corrosion resistance of martensite corrosion resistant plastic die steel. Therefore, it is of great significance to study the influence of heat treatment on the pitting corrosion resistance of Cr13 plastic mould steel to improve the service life of injection mould. In this paper, using domestic 30Cr13 and imported Stavax ESR steel as research materials, the effect of different heat treatment processes on microstructure evolution of Cr13 plastic die steel was studied by means of advanced material analysis technology. The influence of different heat treatment processes on corrosion resistance of Cr13 plastic die steel was studied by electrochemical experiment. The results show that the pitting corrosion resistance of quenched Cr13 plastic die steel increases with the increase of austenitizing temperature. Reducing the content of Cr-rich M23 C _ 2O _ 6 carbides in Cr13 plastic die steel after quenching is beneficial to the improvement of pitting corrosion resistance of this type of plastic die steel. In addition, increasing the cleanliness of steel and reducing the content of TiN inclusion in steel are beneficial to the improvement of pitting corrosion resistance of Cr13 plastic die steel. After tempering at 300 鈩，

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