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井式气体渗氮炉的操作方法
一、预备处理确定原则
First, the principle of preparatory processing and determination
一般结构钢件用调质处理，高温回火温度应该比渗氮温度高20度左右，保温时间不宜过长
The tempering temperature of high temperature tempering should be about 20 degrees higher than that of the nitriding temperature, and the heat preservation time should not be too long.
对冲击韧性要求低的工件，可以采用正火处理，但正火冷却速度要快，断面尺寸较大的工作不得采用正火
For the workpiece with low impact toughness, normalizing can be used, but the cooling rate of the normalizing is faster and the work with larger section size should not be normalized.
38CrMoAl钢应采用调质，否则渗氮层中容易出再针状氮化物，工模具钢渗氮前应淬火-回火处理，不得用退火
38CrMoAl steel should be quenched and tempered, otherwise the nitrides in the nitriding layer will be easily acicular, and the die steel should be quenched and tempered before nitriding, and no annealing can be used.
对一些复杂和精密的零件，渗氮前可进行一次或多次去应力且缓慢升温
For some complex and precise parts, one or more stress and slowly heating up before nitriding
二、工作准备
Two. Work preparation
1、气密性检查
1. Air tightness examination
氮化前应对加热炉、氮化罐和整个氮化系统的管道接头处进行气密性检查，保证氨气不漏和在管路中的畅通无阻。
Before nitriding, check the tightness of the joints of the heating furnace, the nitriding tank and the whole nitriding system, so as to ensure that ammonia is not leaked and unimpeded in the pipeline.
2 、工件工作面的抛光清洁
2, the polishing and cleaning of the work surface of the work piece
要求氮化的表面要经过认真的打磨及仔细的检查，氮化表面应无油迹、锈蚀、尖角、毛刺、碰伤和洗涤不掉的脏物；对于非氮化面要检查防护，涂层是否完整。
Requirements of the nitrided surface after careful grinding and careful examination of the nitride surface should be no oil stains, rust, sharp edges, burrs, bumps and washing away dirt; for non surface nitride to check the protective coating, is complete.
3、检查漏气
3. Check air leakage
用酚酞试纸浸湿后放在怀疑的漏气处，试纸变为红色就证明漏气现象.
With phenolphthalexone soaked in leakage of doubt, litmus red that leakage phenomenon.
三、工艺规范的规定
Three. The regulations of the process
1、渗氮温度
1. Nitriding temperature
1.1、常用500-530℃，能保证氮化物有较大的弥散度，硬度最高
1.1, the commonly used 500-530 C can ensure that the nitrides have greater dispersion and the highest hardness.
1.2、随渗氮温度升高，渗层深度增加，而硬度显著降低，大于550℃渗氮，多数钢种的最高硬度低于1000HV
1.2. With the increase of nitriding temperature, the depth of the permeation layer is increased, and the hardness of the steel is significantly lower than that of 550. The maximum hardness of most steel is lower than 1000HV.
1.3、用两段渗氮法，第二段的温度常低于560℃
1.3. The temperature of the second section is often below 560 centigrade by the two section nitriding method.
2、渗氮时间.
2. Nitriding time.
2.1 渗氮层随时间的延长而增厚，初期增长率大，以后渐趋缓慢，一般渗速在0.01mm/h左右
The 2.1 nitriding layer thickens with the time prolonging, the initial growth rate is big, the later gradually slow down, the general seepage speed is about 0.01mm/h
2.2 随保温时间延长，氮化物聚集长大，硬度下降。温度越高，时间越长，长大越厉害
2.2 with the prolongation of heat preservation time, the accumulation and growth of nitrides and the decrease of hardness. The higher the temperature, the longer the time, the more it grows.
3、氨分解率
3. Ammonia decomposition rate
3.1 分解率为20 一40 ％时活性氮原子多，零件表面可大量吸收氮
When the 3.1 decomposition rate is 20 to 40%, the active nitrogen atom is much, and the surface of the part can absorb a lot of nitrogen.
3.2 分解率超过60 ％则气氛中的氢含量高达52％以上，将产生脱氮作用，此时不仅活性氮原子数量减小，而且大量氢分子和氮分子停滞于零件表面附近，使氮原子不易为表面所吸收，从而使零件表面含氮量降低，渗氮层深度也减薄。
3.2 the decomposition rate of more than 60% in an atmosphere of high hydrogen content is more than 52%, will produce the denitrification effect, not only the quantity of active nitrogen atoms decreases, and a large number of hydrogen and nitrogen molecules in the part near the surface of the stagnation, nitrogen atoms do not absorbed by the surface, so that the surface nitrogen content decreased, the nitrided layer the depth of thinning.
四、渗氮操作
Four, nitriding operation
升温
Heating
升温前应通氨气排气，氨气流量是正常流量的两倍以上，对变形要求严格的，可采用阶梯升温，也可以使升温速度小于50度/h。
Before heating up, ammonia exhaust should be carried out. Ammonia flow rate is two times higher than that of normal flow. For deformation requirements, step heating can be adopted, and heating speed can be less than 50 degrees /h.
2.排气
2. exhaust
一般过升温边排气，在150-200℃内排空，在排气过程中可以用PH试纸方法检查炉罐及管道密封情况；排气阶段，不断通入氨气，使炉压达到200-400Pa（U形管装油）,空气不清除，不能点燃排气管，在升温阶段氨分解率可达70%，炉气中氨气体积大于95%以上，可以减少氨气流量
General heating side exhaust, emptying in 150-200 C, PH test method to check furnace tank and pipeline sealing can be in the process of exhaust; exhaust, continuously introducing ammonia gas, the furnace pressure reaches 200-400Pa (U tube filling), the air is not clear, can ignite the exhaust pipe in the heating stage for ammonia decomposition the rate of up to 70%, furnace gas ammonia volume greater than 95% or more, can reduce the ammonia flow rate
3.保温
3. heat preservation
当温度达到渗氮温度后，调节氨气流量，使氨分解率达到工艺所需要的范围，炉压控制在200-600Pa之间，每15-30分钟测一次氨分解率。
When the temperature reaches the nitriding temperature, the ammonia flow rate is adjusted to make the ammonia decomposition rate reach the required range of the process. The furnace pressure is controlled between 200-600Pa, and the ammonia decomposition rate is measured every 15-30 minutes.
4.冷却
4 cooling
在渗氮结束段后，关闭排气阀，减少氨流量，使氨分解率达到70%左右，保温2小时，减少工件表面脆性；停电降温，保持炉内正压，炉温降到150以下出炉
After the end of nitriding, close the exhaust valve, reduce the ammonia flow rate, make the decomposition rate of ammonia reach 70%, keep the heat for 2 hours, reduce the surface brittleness of the workpieces, cut down the electricity and cool down, keep the positive pressure inside the furnace, and the furnace temperature drops below 150.
First, the principle of preparatory processing and determination
一般结构钢件用调质处理，高温回火温度应该比渗氮温度高20度左右，保温时间不宜过长
The tempering temperature of high temperature tempering should be about 20 degrees higher than that of the nitriding temperature, and the heat preservation time should not be too long.
对冲击韧性要求低的工件，可以采用正火处理，但正火冷却速度要快，断面尺寸较大的工作不得采用正火
For the workpiece with low impact toughness, normalizing can be used, but the cooling rate of the normalizing is faster and the work with larger section size should not be normalized.
38CrMoAl钢应采用调质，否则渗氮层中容易出再针状氮化物，工模具钢渗氮前应淬火-回火处理，不得用退火
38CrMoAl steel should be quenched and tempered, otherwise the nitrides in the nitriding layer will be easily acicular, and the die steel should be quenched and tempered before nitriding, and no annealing can be used.
对一些复杂和精密的零件，渗氮前可进行一次或多次去应力且缓慢升温
For some complex and precise parts, one or more stress and slowly heating up before nitriding
二、工作准备
Two. Work preparation
1、气密性检查
1. Air tightness examination
氮化前应对加热炉、氮化罐和整个氮化系统的管道接头处进行气密性检查，保证氨气不漏和在管路中的畅通无阻。
Before nitriding, check the tightness of the joints of the heating furnace, the nitriding tank and the whole nitriding system, so as to ensure that ammonia is not leaked and unimpeded in the pipeline.
2 、工件工作面的抛光清洁
2, the polishing and cleaning of the work surface of the work piece
要求氮化的表面要经过认真的打磨及仔细的检查，氮化表面应无油迹、锈蚀、尖角、毛刺、碰伤和洗涤不掉的脏物；对于非氮化面要检查防护，涂层是否完整。
Requirements of the nitrided surface after careful grinding and careful examination of the nitride surface should be no oil stains, rust, sharp edges, burrs, bumps and washing away dirt; for non surface nitride to check the protective coating, is complete.
3、检查漏气
3. Check air leakage
用酚酞试纸浸湿后放在怀疑的漏气处，试纸变为红色就证明漏气现象.
With phenolphthalexone soaked in leakage of doubt, litmus red that leakage phenomenon.
三、工艺规范的规定
Three. The regulations of the process
1、渗氮温度
1. Nitriding temperature
1.1、常用500-530℃，能保证氮化物有较大的弥散度，硬度最高
1.1, the commonly used 500-530 C can ensure that the nitrides have greater dispersion and the highest hardness.
1.2、随渗氮温度升高，渗层深度增加，而硬度显著降低，大于550℃渗氮，多数钢种的最高硬度低于1000HV
1.2. With the increase of nitriding temperature, the depth of the permeation layer is increased, and the hardness of the steel is significantly lower than that of 550. The maximum hardness of most steel is lower than 1000HV.
1.3、用两段渗氮法，第二段的温度常低于560℃
1.3. The temperature of the second section is often below 560 centigrade by the two section nitriding method.
2、渗氮时间.
2. Nitriding time.
2.1 渗氮层随时间的延长而增厚，初期增长率大，以后渐趋缓慢，一般渗速在0.01mm/h左右
The 2.1 nitriding layer thickens with the time prolonging, the initial growth rate is big, the later gradually slow down, the general seepage speed is about 0.01mm/h
2.2 随保温时间延长，氮化物聚集长大，硬度下降。温度越高，时间越长，长大越厉害
2.2 with the prolongation of heat preservation time, the accumulation and growth of nitrides and the decrease of hardness. The higher the temperature, the longer the time, the more it grows.
3、氨分解率
3. Ammonia decomposition rate
3.1 分解率为20 一40 ％时活性氮原子多，零件表面可大量吸收氮
When the 3.1 decomposition rate is 20 to 40%, the active nitrogen atom is much, and the surface of the part can absorb a lot of nitrogen.
3.2 分解率超过60 ％则气氛中的氢含量高达52％以上，将产生脱氮作用，此时不仅活性氮原子数量减小，而且大量氢分子和氮分子停滞于零件表面附近，使氮原子不易为表面所吸收，从而使零件表面含氮量降低，渗氮层深度也减薄。
3.2 the decomposition rate of more than 60% in an atmosphere of high hydrogen content is more than 52%, will produce the denitrification effect, not only the quantity of active nitrogen atoms decreases, and a large number of hydrogen and nitrogen molecules in the part near the surface of the stagnation, nitrogen atoms do not absorbed by the surface, so that the surface nitrogen content decreased, the nitrided layer the depth of thinning.
四、渗氮操作
Four, nitriding operation
升温
Heating
升温前应通氨气排气，氨气流量是正常流量的两倍以上，对变形要求严格的，可采用阶梯升温，也可以使升温速度小于50度/h。
Before heating up, ammonia exhaust should be carried out. Ammonia flow rate is two times higher than that of normal flow. For deformation requirements, step heating can be adopted, and heating speed can be less than 50 degrees /h.
2.排气
2. exhaust
一般过升温边排气，在150-200℃内排空，在排气过程中可以用PH试纸方法检查炉罐及管道密封情况；排气阶段，不断通入氨气，使炉压达到200-400Pa（U形管装油）,空气不清除，不能点燃排气管，在升温阶段氨分解率可达70%，炉气中氨气体积大于95%以上，可以减少氨气流量
General heating side exhaust, emptying in 150-200 C, PH test method to check furnace tank and pipeline sealing can be in the process of exhaust; exhaust, continuously introducing ammonia gas, the furnace pressure reaches 200-400Pa (U tube filling), the air is not clear, can ignite the exhaust pipe in the heating stage for ammonia decomposition the rate of up to 70%, furnace gas ammonia volume greater than 95% or more, can reduce the ammonia flow rate
3.保温
3. heat preservation
当温度达到渗氮温度后，调节氨气流量，使氨分解率达到工艺所需要的范围，炉压控制在200-600Pa之间，每15-30分钟测一次氨分解率。
When the temperature reaches the nitriding temperature, the ammonia flow rate is adjusted to make the ammonia decomposition rate reach the required range of the process. The furnace pressure is controlled between 200-600Pa, and the ammonia decomposition rate is measured every 15-30 minutes.
4.冷却
4 cooling
在渗氮结束段后，关闭排气阀，减少氨流量，使氨分解率达到70%左右，保温2小时，减少工件表面脆性；停电降温，保持炉内正压，炉温降到150以下出炉
After the end of nitriding, close the exhaust valve, reduce the ammonia flow rate, make the decomposition rate of ammonia reach 70%, keep the heat for 2 hours, reduce the surface brittleness of the workpieces, cut down the electricity and cool down, keep the positive pressure inside the furnace, and the furnace temperature drops below 150.
