余熱正火(退火)

⑴得當掌握鍛件進爐前的溫度。當零件溫度較高時需求對鍛件進行吹風冷卻，使零件溫度降低到所需求的正火溫度，同時熱處分爐功率需求有一定的充裕，開始制造前和少量鍛件溫度低時進行加熱。

⑵確定合理保溫時間。保溫時間過長會會造成晶粒粗壯，保溫時間過短會造成構造轉變不充裕。可憑據鍛件質料、形狀和尺寸通過實驗確定。

余熱等溫正火

⑴ 鑄造后鍛件溫度掌握。鍛件成形后的溫度必需在Ar3(對亞共析鋼)以上，鍛后零件溫度穩定時可接納干脆急冷的方法;鍛后零件溫度顛簸較大或鍛件截面變更大時，必需增加均溫歷程，急冷前使零件溫度均勻一致，否則會造成急冷后鍛件或不同截面溫度相差大，產生非常構造(貝氏體或馬氏體)。

⑵ 急冷冷卻速率掌握。急冷工序中要求鍛件快速冷卻，同時冷卻后統一鍛件和同批鍛件溫度均勻一致(或相近)。同時需求對急冷速率加以掌握，過快的急冷速率會在鍛件構造中產生魏氏構造。一般急冷速率掌握在30～42℃/min。

⑶ 急冷后溫度掌握。急冷后必需包管鍛件溫度在珠光體轉變區，不能低于貝氏體轉變開始溫度(Bs)，否則構造中會出現貝氏體(或粒狀貝氏體)構造;如急冷后溫度過高會造成先共析鐵素體量增加，構造轉變后珠光體片層間距大，造成零件硬度低。鍛件急冷后溫度一般掌握在質料Bs溫度以上在80～100℃。

⑷ 等溫溫度的選定。等溫溫度的崎嶇干脆影響到等溫正火后鍛件的硬度，等溫溫度高則硬度低，等溫溫度低則硬度高。等溫溫度一般為鍛件質料Bs溫度以上50～80℃，具體溫度需憑據鍛件的質料、形狀經實驗進行確定。

⑸ 等溫保溫時間確鑿定。珠光體轉變產生在等溫歷程中，是以必需有足夠的保溫時間，如等溫時間過短會造成過冷奧氏體沒有一切轉變為珠光體，在隨后的冷卻歷程中轉變為貝氏體或馬氏體，造成等溫處分后構造分歧格和硬度高。等溫時間可憑據質料的等溫轉變曲線進行初步確定，并憑據實驗情況進行調整。

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Waste heat normalization (annealing)

(1) It is necessary to grasp the temperature before the forging is put into the furnace. When the temperature of the part is high, the forging is required to be blown to cool, so that the temperature of the part is lowered to the required normalizing temperature, and the power demａnd of the heat dividing furnace is sufficient, and heating is performed before the start of manufacturing and when the temperature of a small amount of forging is low.

(2) Determine the reasonable holding time. If the holding time is too long, the crystal grains will be thick and the holding time will be too short, which will cause the structural transformation to be insufficient. The material, shape and size of the forging can be determined experimentally.

Isothermal isotherm

(1) Master temperature of forging after casting. The temperature after forming the forging must be above Ar3 (for the sub-eutectoid steel). When the temperature of the forged part is stable, the method of quenching and quenching can be accepted. When the temperature of the forged part is large or the section of the forging is changed greatly, the temperature history must be increased. Make the temperature of the parts uniform before quenching, otherwise the forgings or different cross-section temperatures will be greatly different after quenching, resulting in very structural (bainite or martensite).

(2) The quenching cooling rate is mastered. In the quenching process, the forgings are required to be rapidly cooled, and at the same time, the uniform forgings and the same batch of forgings are uniformly uniform (or similar) after cooling. At the same time, the demａnd for the quenching rate is mastered, and the too fast quenching rate will produce the Wei's structure in the forging structure. Generally, the quenching rate is controlled at 30 to 42 ° C / min.

(3) Temperature control after quenching. After quenching, the forging temperature must be in the pearlite transformation zone, and should not be lower than the bainite transformation starting temperature (Bs). Otherwise, the bainite (or granular bainite) structure will appear in the structure; if the temperature is too high after quenching, it will cause The amount of ferrite is increased first, and the spacing of the pearlite sheets after the structural transformation is large, resulting in low hardness of the parts. After the forging is quenched, the temperature is generally above 80 ° C to 100 ° C above the Bs temperature.

(4) Selection of isothermal temperature. The roughness of the isothermal temperature simply affects the hardness of the forged part after isothermal normalizing, the hardness is low when the isothermal temperature is high, and the hardness is high when the isothermal temperature is low. The isothermal temperature is generally 50 to 80 ° C above the Bs temperature of the forging material. The specific temperature needs to be determined experimentally according to the material and shape of the forging.

(5) The isothermal holding time is fixed. The pearlite transformation occurs in the isothermal history, so it is necessary to have sufficient holding time. If the isothermal time is too short, the supercooled austenite will not be transformed into pearlite, and it will be transformed into bainite or horse in the subsequent cooling process. The body, causing the isothermal division to have a divergent lattice and a high hardness. The isothermal time can be initially determined by the isothermal transformation curve of the material and adjusted according to the experimental conditions.