冷拔無縫鋼管熱處理工藝：退火和正火

冷拔無縫鋼管熱處理工藝：退火和正火.冷拔無縫鋼管退火與正火的主要區別： 1、正火的冷卻速度比退火稍快，過冷度較大2、正火後所得到的組織比較細，強度和硬度比退火高一些。退火與正火的選擇 ：
Heat treatment process of cold-drawn seamless steel tube: annealing and normalizing. The main differences between annealing and normalizing of cold-drawn seamless steel tube: 1. The cooling speed of normalizing is slightly faster than annealing, the degree of undercooling is larger 2. The microstructure obtained after normalizing is finer, and the strength and hardness are higher than annealing. Selection of annealing and normalizing:
1、含碳量＜0.25％的低碳鋼，通常采用正火代替退火。因為較快的冷卻速度可以防止低碳鋼沿晶界析出遊離三次滲碳體，從而提高沖壓件的冷變形性能；用正火可以提高鋼的硬度，低碳鋼的切削加工性能；在沒有其它熱處理工序時，用正火可以細化晶粒，提高冷拔無縫鋼管強度。
1. Low carbon steel with carbon content less than 0.25% is usually normalized instead of annealing. Because the faster cooling speed can prevent the free tertiary cementite from precipitating along the grain boundary of low carbon steel, thus improving the cold deformation performance of stamping parts; normalizing can improve the hardness of steel and the cutting performance of low carbon steel; normalizing can refine grains and improve the strength of cold-drawn seamless steel tube without other heat treatment processes.
２、含碳量在0.25～0.5％之間的中碳鋼也可用正火代替退火，雖然接近上限碳量的冷拔無縫鋼管正火後硬度偏高，但尚能進行切削加工，而且正火成本低、生產率高。
2. Medium-透水地坪carbon steel with carbon content between 0.25% and 0.5% can also be normalized instead of annealing. Although the hardness of cold-drawn seamless steel pipe approaching the upper limit of carbon content is higher after normalizing, it can still be machined, and the normalizing cost is low and the productivity is high.
３、含碳量在0.5～0.75％之間的鋼，因含碳量較高，正火後的硬度顯著高於退火的情況，難以進行切削加工，故一般采用完全退火，降低硬度，改善切削加工性。
3. Steel with carbon content between 0.5% and 0.75% is difficult to be machined because of its high carbon content and its hardness after normalizing is significantly higher than that after annealing. Therefore, complete annealing is generally used to reduce hardness and improve machinability.
４、 含碳量＞ 0.75％的高碳鋼或工具冷拔無縫鋼管一般均采用球化退火作為預備熱處理，如有網狀二次滲碳體存在，則應先進行正火消除。退火是將工件加熱到適當溫度，保持一定時間，然後緩慢冷卻的熱處理工藝。緩冷是退火的主要特點，退火件一般隨爐冷卻至550℃以下時出爐空冷。退火是應用非常廣泛的熱處理，在工模具或機械零件等的制造過程中，經常作為預備熱處理安排在鑄鍛焊之後，切削（粗）加工之前，用以消除前一道工序所帶來的某些缺陷，並為隨後的工序做好準備。
4. Spheroidizing annealing is generally used as the preparatory heat treatment for high carbon steel or cold-drawn seamless steel pipes with carbon content of more than 0.75%. If there are reticulated secondary cementite, normalizing should be carried out first. Annealing is a heat treatment process in which the workpiece is heated to an appropriate temperature for a certain period of time and then slowly cooled. Slow cooling is the main feature of annealing. The annealed parts are generally cooled with the furnace to below 550 (?) Annealing is a widely used heat treatment. 彩色沥清地坪In the manufacturing process of dies, dies and mechanical parts, it is often arranged as a preparatory heat treatment after casting, forging and welding, before cutting (rough) to eliminate some defects caused by the previous process and prepare for the subsequent process.
退火目的①降低材料硬度，以利於切削加工；②消除各類應力，防止零件變形；③細化粗大晶粒，改善內部組織為最終熱處理做好準備。
The purpose of annealing is: (1) to reduce the hardness of materials to facilitate cutting; (2) to eliminate various stresses and prevent deformation of parts; and (3) to refine coarse grains and improve internal structure in preparation for final heat treatment.