固溶温度对GH4202合金组织及拉伸性能的影响

为充分挖掘沉淀强化型镍基高温合金GH4202管材性能,以满足我国航天新型发动机的要求,研究了固溶处理温度对合金组织及拉伸性能的影响规律.结果表明,在1 050~1 075℃范围固溶处理后合金晶粒度无明显变化,当固溶温度升至1 100℃时,合金局部出现异常晶粒长大,当固溶温度达到1 150℃时,合金晶粒均匀长大.随固溶温度升高,合金晶界硼、碳化物数量明显减少,由链状向孤立的颗粒状转变.随固溶温度升高,GH4202合金室温及高温拉伸强度均呈降低趋势,尤其以屈服强度降低幅度最为显著.合金的室温面缩率随固溶温度升高而降低,且降低幅度较大,但室温断裂延伸率变化并不显著;700℃下合金的断面收缩率与断裂延伸率随固溶温度的变化均表现为先升高后降低的趋势.GH4202合金最佳固溶处理工艺为1 110℃保温30 min后水冷,此时合金晶粒度为5.0级、晶界碳化物呈细小链状,晶内沉淀强化γ'相弥散析出,可保证合金具有优异的室温及高温力学性能.

Effect of solution temperature on microstructure and tensile properties of GH4202 superalloy

In order to meet the requirement of GH4202 tubes used for the new type engine, effects of the solution temperature on microstructure and tensile properties of the GH4202 superalloy were investigated.The results showed that the grain size of the alloy after solution treatment shows no obvious change in the temperature range of 1050 to 1075℃.When the temperature reaches 1150℃, the grains grow homogeneously, amount of borides and carbides on the grain boundaries decreases obviously with the increase temperature.There is a decreasing trend in the tensile strength of the alloy at both room temperature (RT) and high temperature with increase of temperature, especially for the yield strength.When the temperature increases, the reduction of area of the alloy decreases greatly, while the fracture elongation does not change significantly.Both the fracture elongation and the reduction of area of the alloy after tensile test below 700℃ increase first and then decrease with the temperature increase.The optimism treatment condition for the GH4202 alloy is heated at 1110℃ for 30min, and then cooled by water.The grain size was controlled around 4-5 grade, the carbides at the grain boundary exhibites small chain.The precipitation process inside the grains hardenss γ′ dispersed phases, so that the GH4202 alloy can obtain an excellent mechanical properties at a room and a high temperature.