來源:http://texjob.com.cn/ 發(fā)布時(shí)間:2021-04-15
保溫時(shí)間的選擇原則是在正常固溶熱處理溫度下,使強(qiáng)化相達(dá)到滿意的溶解程度,并使固溶體充分均勻及晶粒細(xì)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(shí)間主要是根據(jù)淬火加熱溫度、合金的本性、制品的種類、固溶前組織狀態(tài)(強(qiáng)化相分布特點(diǎn)和尺寸大小)、產(chǎn)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(huán)爐,連續(xù)還是非連續(xù)加熱)、加熱介質(zhì)、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(shí)間應(yīng)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(chǎn)品的形狀。淬火加熱時(shí)的保溫時(shí)間與制品的形狀(包括斷面厚度的尺寸大小)有密切的關(guān)系,斷面厚度越大,保溫時(shí)間就相應(yīng)越長。截面大的半成品及形變量小的工件,強(qiáng)化相較粗大,保溫時(shí)間應(yīng)適當(dāng)延長,使強(qiáng)化相充分溶解。大型鍛件和模鍛件的保溫時(shí)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(shí)的保溫時(shí)間與加熱溫度是緊密相關(guān)的,加熱溫度越高,強(qiáng)化相溶入固溶體的速度越大,其保溫時(shí)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(qiáng)化相的溶解。變形程度越大,強(qiáng)化相尺寸越小,保溫時(shí)間可短些。經(jīng)冷變形的工件在加熱過程中要發(fā)生再結(jié)晶,應(yīng)注意防止再結(jié)晶晶粒過分粗大。固溶處理前不應(yīng)進(jìn)行臨界變形程度的加工。擠壓制品的保溫時(shí)間應(yīng)當(dāng)縮短,以保持?jǐn)D壓效應(yīng)。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(shí)間過長,將由于再結(jié)晶過程的發(fā)生,而導(dǎo)致局部或全部擠壓效應(yīng)的消失,使制品的縱向強(qiáng)度降低。擠壓時(shí)的變形程度越大,需要保溫的時(shí)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(yù)先經(jīng)過淬火的制品,再次進(jìn)行溶火加熱時(shí)其保溫時(shí)間可以顯著縮短。而預(yù)先退火的制品與冷加工制品相比,其強(qiáng)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(qiáng)化相多且大,因此保溫時(shí)間應(yīng)長些。固溶處理和均勻化共同的目的是使強(qiáng)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(jié)晶相而提高均勻化溫度就容易過燒。此外,均勻化退火時(shí)間長,經(jīng)濟(jì)效益低,因此可以根據(jù)制品合金本性以及加工工藝考慮均勻化和淬火的聯(lián)動工藝,解決強(qiáng)化相充分固溶問題,因?yàn)榇笞冃魏蠼M織中的強(qiáng)化相破碎嚴(yán)重,尺寸變小,在淬火時(shí)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.