基于组织的大型锻件热锻表面开裂准则研究

项目名称： 基于组织的大型锻件热锻表面开裂准则研究

项目编号： No.51505416

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 王振华

作者单位： 燕山大学

项目金额： 20万元

中文摘要： 大型锻件在重型机械和能源装备等领域具有战略地位，而热锻表面开裂严重制约其发展。大型锻件锻造时间长、变形复杂，表层组织不断演化（晶粒尺寸变化和第二相析出），其热塑性也不断改变。. 本项目以316LN核电主管道钢和18Mn18Cr0.5N护环钢为试验材料，对热锻表面开裂行为进行研究。主要计划：1）分析不同晶粒尺寸条件下裂纹的萌生和发展过程，阐明晶粒尺寸对开裂的影响机理；2）确定晶粒尺寸与开裂的定量关系（晶粒宏观不均匀性对开裂的影响，由微区晶粒尺寸的影响来体现）；3）明确可促进开裂的第二相的特性，揭示促进机理；4）确立第二相特性与开裂的定量关系；5）引入表征晶粒和第二相的参数，借鉴经典开裂准则，进而建立大型锻件热锻表面开裂准则，并进行优化和实践。. 揭示组织对开裂的影响机理，确定微观组织与宏观开裂的定量关系，进而建立针对大型锻件的热锻表面开裂准则，是本项目的创新点。

中文关键词： 组织演变；锻造缺陷；裂纹；锻造工艺

英文摘要： Heavy forging is of strategic importance to heavy machinery, energy equipment, etc, but surface cracking during hot forging seriously affects its development. Due to the long forging period and complex deformation process of heavy forings, the surface microstructure continuously evolutes (change in grain size and second phase precipitation), which have significant influence on the hot ductility. . In this proposal, we prepare 316LN main pipe steel and 18Mn18Cr0.5N retaining ring steel, and their surface cracking behaviors during hot forging are systematically investigated. The main work includes: 1) To analyze the nucleation and propagation of cracks under different grain size conditions, and to reveal the impact mechanism of grain size on surface cracking; 2) To establish the quantitative relationship between grain size and cracking (The effect of macro-nonuniformity of grain on cracking can be characterized by the effect of grain size in micro-region); 3) To investigate the characteristics of second phase which can promote cracking, and to reveal the impact mechanism; 4) To establish the quantitative relationships between second phase characteristics and cracking; 5) To establish the surface cracking criterion during hot forging for heavy forgings by combining material parameters (characterizing grain and second phase), and to evaluate and optimize it.. Revealing the impact mechanisms of microstructure on surface cracking and the quantitative relationship between microstructure and macro-cracking, and establishing the cracking criterion for heavy forgings are the main innovations.

英文关键词： microstructure evolution;forging defect;crack;forging process