新淬火状态铝合金板的成形极限

Forming limits for as-quenched aluminum alloy sheet

论述了硬铝合金成形工艺中应变路径、固溶热处理和时效过程对成形极限的影响,由试验得到了单向拉伸预应变和固溶热处理后时效过程中的成形极限图FLD(Form-ing Lim itD iagram),重点研究了固溶热处理后时效过程中成形极限的变化,并得到了铝合金在时效过程中的成形极限应力图FLSD(Form ing Lim it Stress D iagram).结果表明,原始退火状态材料的成形极限高于新淬火状态材料的成形极限,且新淬火状态材料的成形极限随时效时间增加而降低,原因主要在于固溶热处理过程中材料组织状态的变化和应变硬化指数n在时效过程中的降低;成形极限应变的降低导致成形极限应力也随时效时间增加而降低.

FLD （forming limit diagram） was influenced by the material properties as well as forming process, such as strain path and heat-treatment states, etc. Some experimental FLDs were constructed for 2D12 aluminum alloy in the annealed, pre-strained and various aging time conditions after solution heat-treatment by rigid punch bulging. Based on the experimental results, the FLSD （forming limit stress diagram） was determined. By comparing and analyzing the FLD and FLSD, it is indicated that the FLD of annealed condition is higher than the FLD after heat-treatment and the aging hardening lowers the FLD. The results mainly depend on the metallurgical structure transformation during solution heat treatment and the decrease of hardening value n with aging. Furthermore, aging hardening lowers the FLSD mostly because it lowers the FLD. The result may be available for the sheet forming process design and numerical simulation.