Ni-Cr-Mo-V钢合金化和热处理对材料的影响

Effect of Alloying and Heat Treatment on Ni-Cr-Mo-V Steel

为满足船件及大型防护工程等大厚度、高硬度、可焊接防护钢需求,在Ni-Cr-Mo-V系钢的基础上改进合金成分和工艺。采用光学显微镜和扫描电子显微镜研究热处理工艺和合金元素对材料性能的影响,分析不同热处理工艺和合金元素下试验钢的显微组织特征。通过调整C、Si、Cr、Ni含量及热处理工艺参数,寻找最佳方案。发现在430~520℃区间回火时,随着回火温度的提升,材料强度先提升后降低;提高C和Cr元素的含量有利于提高材料屈服强度和抗拉强度,但是Cr能显著提高韧脆转变温度,使冲击韧度急剧下降,而提高Ni元素在提升强度和硬度的同时,保证低温冲击韧性。

In order to meet the requirements of large thickness,high hardness and weldable shield steel for ship components and large-scale protective engineering,improvement of alloying composition and process are studied on the basis of Ni-Cr-Mo-V steel.Optical microscope and scanning electron microscope are adopted to study the influence of heat treatment process and alloying element on material property,and to investigate the characteristic of the microstructure of the test steel of different heat treatment processes and alloying elements.By adjusting the content of C,Si,Cr and Ni and the heat treatment parameter,it is found that when tempering at 430~520℃,with increase of the tempering temperature,the material strength increases and then decreases.Increase of C and Cr contents are beneficial for improving yield strength and tensile strength of the material,while increase of Cr content can significantly raise the ductile-brittle transition temperature and cause drastic reduction of impact toughness,but increase of Ni content can not only improves strength and hardness property,but also guarantees the low temperature impact toughness.