Re: [其他] 回火退火及淬火的不同

看板Mechanical作者maddeath時間10年前 (2013/10/14 14:04)推噓3(3推 0噓 12→)

留言15則, 3人參與討論串3/3 (看更多)

※ 引述《kevin8290 (泰國王)》之銘言： : 原文吃光光 : 小弟剛好也有個退火的問題 : 藉由這標題上來請教一下 : 冷作之工件為消除應力，可施以（Ａ）弛力退火（Ｂ）回火 : （Ｃ）製程退火（Ｄ）應變硬化 : 此題是一本高職機械製造課本後面的練習題 : 根據課本內容，直覺答案是（Ａ），不過正確答案是（Ｃ） : 掃瞄課本內容如此連結 http://i.imgur.com/0JSYeMT.png

: 難道是答案給錯了？ : 還是要用更細微的探討才能解此題？個人覺得其實是題目敘述不好所造成的誤會因為如果是消除應力選A或C都對弛力退火(應力消除退火)是用材料在塑性變形完後所作的熱處理製程退火是在冷作製程中，為了避免加工硬化造成材料破裂，因此施以熱處理軟化材料並回復材料的延展性後，繼續冷作製程所以要是將題目改為 [冷作製程中為避免加工造成應力斷裂所施以的熱處理?] 就比較不會有爭議....... 為了避免小弟的認知錯誤，補上原文 Process Annealing is used to treat work-hardened parts made out of low-Carbon steels (< 0.25% Carbon). This allows the parts to be soft enough to undergo further cold working without fracturing. Process annealing is done by raising the temperature to just below the Ferrite-Austenite region, line A1on the diagram. This temperature is about 727 ºC (1341 ºF) so heating it to about 700 ºC (1292 ºF) should suffice. This is held long enough to allow recrystallization of the ferrite phase, and then cooled in still air. Since the material stays in the same phase through out the process, the only change that occurs is the size, shape and distribution of the grain structure. This process is cheaper than either full annealing or normalizing since the material is not heated to a very high temperature or cooled in a furnace. Stress Relief Anneal is used to reduce residual stresses in large castings, welded parts and cold-formed parts. Such parts tend to have stresses due to thermal cycling or work hardening. Parts are heated to temperatures of up to 600 - 650 ºC (1112 - 1202 ºF), and held for an extended time (about 1 hour or more) and then slowly cooled in still air. -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 60.244.141.8

推

wgst88w

10/14 15:09, , 1^F

10/14 15:09, 1^F

→

wgst88w

10/14 15:15, , 2^F

10/14 15:15, 2^F

推

kevin8290

10/15 12:29, , 3^F

10/15 12:29, 3^F