來源:http://www.gdjsdtc.com/ 發布時間:2021-04-15
保溫時間的選擇原則是在正常固溶熱處理溫度下,使強化相達到滿意的溶解程度,并使固溶體充分均勻及晶粒細小。
The selection principle of holding time is to make the strengthening phase dissolve satisfactorily at normal solution heat treatment temperature, and make the solid solution fully uniform and the grain fine.
鋁合金的淬火保溫時間主要是根據淬火加熱溫度、合金的本性、制品的種類、固溶前組織狀態(強化相分布特點和尺寸大小)、產品的形狀(包括斷面厚度的尺寸大小)、加熱方式(鹽浴爐及空氣循環爐,連續還是非連續加熱)、加熱介質、冷卻方式和裝爐量的多少,以及組織性能的要求等因素來確定。
The quenching holding time of aluminum alloy mainly depends on the quenching heating temperature, the nature of the alloy, the type of products, the microstructure before solution (the distribution characteristics and size of strengthening phase), the shape of the product (including the size of section thickness), the heating mode (salt bath furnace and air circulation furnace, continuous or discontinuous heating), the heating medium, the cooling mode and the amount of charging, and so on It is determined by the requirements of organization and performance.
對于同一牌號的合金,確定保溫時間應考慮以下因素
For the same brand of alloy, the following factors should be considered in determining the holding time
(1)產品的形狀。淬火加熱時的保溫時間與制品的形狀(包括斷面厚度的尺寸大小)有密切的關系,斷面厚度越大,保溫時間就相應越長。截面大的半成品及形變量小的工件,強化相較粗大,保溫時間應適當延長,使強化相充分溶解。大型鍛件和模鍛件的保溫時間比薄件的長好幾倍。
(1) The shape of the product. The holding time during quenching is closely related to the shape of the product (including the size of the section thickness). The larger the section thickness is, the longer the holding time is. For semi-finished products with large cross-section and workpieces with small deformation, the strengthening phase is coarse, and the holding time should be appropriately extended to make the strengthening phase fully dissolve. The holding time of heavy forgings and die forgings is several times longer than that of thin ones.
(2)加熱溫度。淬火加熱時的保溫時間與加熱溫度是緊密相關的,加熱溫度越高,強化相溶入固溶體的速度越大,其保溫時間就要短些。
(2) Heating temperature. The higher the heating temperature is, the faster the strengthening phase dissolves into the solid solution, and the shorter the holding time is.
(3)塑性變形程度及制品種類。熱處理前的壓力加工可加速強化相的溶解。變形程度越大,強化相尺寸越小,保溫時間可短些。經冷變形的工件在加熱過程中要發生再結晶,應注意防止再結晶晶粒過分粗大。固溶處理前不應進行臨界變形程度的加工。擠壓制品的保溫時間應當縮短,以保持擠壓效應。對于采用擠壓變形程度很大的擠壓材做毛料的模鍛件,如果淬火加熱的保溫時間過長,將由于再結晶過程的發生,而導致局部或全部擠壓效應的消失,使制品的縱向強度降低。擠壓時的變形程度越大,需要保溫的時間就越短。
(3) Plastic deformation degree and product type. Pressure processing before heat treatment can accelerate the dissolution of strengthening phase. The larger the deformation, the smaller the size of strengthening phase and the shorter the holding time. The recrystallization of cold deformed workpieces during heating should be avoided. The critical deformation should not be processed before solution treatment. The holding time of extruded products should be shortened to maintain the extrusion effect. If the holding time of quenching heating is too long, the partial or total extrusion effect will disappear due to the recrystallization process, and the longitudinal strength of products will be reduced. The greater the degree of deformation, the shorter the holding time.
(4)原始組織。預先經過淬火的制品,再次進行溶火加熱時其保溫時間可以顯著縮短。而預先退火的制品與冷加工制品相比,其強化相的溶解速度顯著變慢。
(4) The original organization. The heat preservation time of pre quenched products can be significantly shortened when they are heated again. However, the dissolution rate of strengthening phase of pre annealed products is significantly slower than that of cold processed products.
(5)坯料均勻化程度。均勻化不充分的制品,殘留的強化相多且大,因此保溫時間應長些。固溶處理和均勻化共同的目的是使強化相充分溶解,但是一般情況下,均勻化退火爐的精度較低,因此為了充分消除非平衡結晶相而提高均勻化溫度就容易過燒。此外,均勻化退火時間長,經濟效益低,因此可以根據制品合金本性以及加工工藝考慮均勻化和淬火的聯動工藝,解決強化相充分固溶問題,因為大變形后組織中的強化相破碎嚴重,尺寸變小,在淬火時更容易固溶。
(5) The homogenization degree of the blank. If the homogenization is not enough, the residual strengthening phase is large, so the heat preservation time should be longer. The common purpose of solution treatment and homogenization is to make the strengthening phase fully dissolved, but in general, the accuracy of homogenization annealing furnace is low, so it is easy to overburnt in order to eliminate the non-equilibrium crystalline phase and increase the homogenization temperature. In addition, the homogenization annealing time is long and the economic benefit is low. Therefore, the linkage process of homogenization and quenching can be considered according to the nature of the product alloy and the processing technology to solve the problem of full solid solution of strengthening phase. Because the strengthening phase in the structure is seriously broken after large deformation and the size becomes smaller, it is easier to solid solution during quenching.