Effect On Microstructure And Properties Of Heating Treatment On Novel High Aluminum Bronzes Alloys

Aluminum bronze alloy is the development potential material to drawing mould androlling die because of its stable rigidity, high coefficient of heat conductivity and easysubsequent polishing procedure. When it has a low Al-content, it will lead to poor qualityof strength and hardness. However, a high Al-content will result in weak plasticity andtoughness which is the main obstacle hindering its application. So, it is necessary toprepare a comprehensive performance Aluminum bronze alloy.This paper aimed at the actual status and performance requirements of aluminumbronze alloy used in mould, chooses Cu-l2Al as the research object. By adding elementsuch as Fe、Ni、Mn prepared a new high aluminum bronze. Solution and heat treated thealloy, and discussed the influence of solution temperature, solution preservation time, agingtemperature and time to the structure and mechanical properties. Studied the effect ofsolution aging process, loading force, speed and temperature to the friction wearperformance of the novel high aluminum bronze alloy with UMT-2friction and wear tester.Studied the corrosion behavior of high aluminum bronze alloy using the M283-potentiostatand whole soak static corrosion test. The main results show as below:The cast structure phase of novel high aluminum bronze alloy Cu-l2Al-X mainly is α、β′、γ2and k. Compared with the traditional aluminum bronze alloy ZCuAl10Fe3, content ofhard phase γ2and k significantly increase, at the same time HRC hardness and tensilestrength obviously rise as well. While compared with aluminum bronze of14%and aboveAl content, it has good plastic toughness and comprehensive mechanical properties whenstrength and hardness differ not quite. After aging of novel high aluminum bronze alloy,discussed the structure and mechanical properties before and after. Precipitated phasegradually increase and widely distribute with the addition of aging temperature and timewhich strengthen the alloy and make the hardness and tensile strength reach the highest. Ifcontinue adding the temperature or prolonging holding time, overaging phenomenon willappear and hardness and tensile strength will drop. Aging temperature and time havedifferent effect on elongation. It first rise then fall with the aging temperature addition.While under a certain aging temperature, it fall with the aging time addition；the novel highaluminum bronze which had the best hardness, tensile strength and elongation rate after950℃×2h solution(cooling in oil)+550℃×4h aging(cooling in air),in this solution and aging process parameter, the hardness, toughness，tensile strength and elongation rate is upto42.6HRC,6.456J,890MPa and9.84%.The wear-friction behavior of the novel high aluminum bronze alloy is studied withmaking use of UMT-2friction and wear tester, the results show that friction factor and wearloss of the novel high aluminum bronze alloy under the condition of solution and agingtreatment were lower than the casting; with the load force increasing, the wear loss of thealloy shows a upward trend, while the coefficient of the friction shows a downward firstthen upward trend, Effect of speed is mainly because the sub-surface deformation andsurface temperature changed, it has significantly effect at the novel high aluminum bronzealloy in casting because of its microstructure not well-distributed; with the increasing oftemperature, for the Cu-12Al-X/CA alloy, primary hard phase γ2and k because of thick andbig can play a good supporting role to resist the friction and wear, wear mechanism isadhesive wear and abrasive wear mixed together, while for the Cu-12Al-X/HT alloy, hardphase γ2and k because of trivial and dispersion distribution cannot play a good supportingrole to resist the friction and wear, wear mechanism is adhesive wear mainly.The corrosion behavior of the novel high aluminum bronze alloy is studied withmaking use of the M283-potentiostat and whole soak static corrosion test， the resultsindicate that the corrosion rate of the novel high aluminum bronze is low in3.5%NaClsolution. The corrosion rate is only0.0295g/m~2·h,after the condition of solution at heattreatment (950oC for2hours and aging at550oCfor4hours), the corrosion rate reduce go astep further, the novel high aluminum bronze suffers dealloying corrosion, the corrosion ismain occur oxygen depolarization reaction.