Analysis of Void Closure during Open Die Forging Process of Large Size Steel Ingots
Analysis of Void Closure during Open Die Forging Process of Large Size Steel Ingots
复制标题
大规格钢锭开模锻造过程中空隙闭合分析
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
M. Jahazi
中科院分区：
文献类型：
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作者：
N. Harris;D. Shahriari;M. Jahazi
由高强度钢制成的大尺寸锻造锭广泛用于航空航天、运输和能源应用。铸态铸锭中内部空隙的存在可显著影响最终产品的机械性能。因此，必须在开式模锻工艺的第一步中消除此类内部缺陷。在本文中，在钢坯中的空洞定位在整个钢锭破裂过程中，特别是在大钢锭尺寸钢镦粗步骤的空洞闭合的效果进行了定量研究。本研究中所使用的材料模型为新的高强度钢的Hansel-Spittel。根据现有的工业数据，使用Forge NxT 1.0®模拟铸锭锻造过程（3D模拟）。使用半解析空隙闭合模型评估了10个虚拟现有空隙的闭合程度。研究发现，镦粗工艺对核心区和中部坯料上部（包括死金属区（DMZ）内的某些区域）的空洞闭合最有效。测定了体积应变率，并观察到两种类型的惯性效应。计算和讨论了空洞闭合对累积等效变形的依赖关系。从相对空隙闭合和体积应变率的信息的原始组合提供了一种方法，以优化锻造过程中的空隙消除。
Large size forged ingots, made of high strength steel, are widely used in aerospace, transport and energy applications. The presence of internal voids in the as-cast ingot may significantly affect the mechanical properties of final products. Thus, such internal defects must be eliminated during first steps of the open die forging process. In this paper, the effect of in-billet void positioning on void closure throughout the ingot breakdown process and specifically the upsetting step in a large ingot size steel is quantitatively investigated. The developed Hansel-Spittel material model for new high strength steel is used in this study. The ingot forging process (3D simulation) was simulated with Forge NxT 1.0® according to existing industrial data. A degree of closure of ten virtual existing voids was evaluated using a semi-analytical void closure model. It is found that the upsetting process is most effective for void closure in core regions and central upper billet including certain areas within the dead metal zone (DMZ). The volumetric strain rate is determined and two types of inertial effects are observed. The dependence of void closure on accumulated equivalent deformation is calculated and discussed in relation to void in-billet locations. The original combination of information from both relative void closure and the volumetric strain rate provides a way to optimize the forging process in terms of void elimination.