A kind of MIM manufacturing process without magnetic 17-4PH stainless steel partsTechnical field
The invention discloses a kind of MIM manufacturing process, be specially a kind of MIM manufacturing process without magnetic 17-4PH stainless steel parts.Belong to metal injection molded technical field.
Background technology
Metal injection moulding (MetalinjectionMolding, MIM) is the manufacturing process that a kind of plasticising compound by metal dust and its binding agent is injected in model.It is first mixed with binding agent by selected powder, then compound carried out the shape of granulating again required for injection moulding.The feature of its VISCOUS FLOW is given compound by polymer, and contribute to being shaped, the uniformity of mould filling and powder packing.Get rid of binding agent after being shaped, then degreasing base is sintered.Some sintered products also carry out further densification, heat treatment or machined possibly.Sintered products not only has the complicated shape the same with injection molding of plastics method resulting product and high accuracy, and has the physics close with forging, chemistry and mechanical performance.
17-4PH precipitation-hardening stainless steel, 316L stainless steel and 304L stainless steel are a few class stainless steel materials that metal powder injection molding (being called for short MIM) is conventional, 17-4PH precipitation-hardening stainless steel intensity hardness is high, corrosion resistance is good, is magnetic, the general structural member being used as not require magnetic; The stainless corrosion resistance of 316L and 304L is good, does not have magnetic, but intensity and hardness ratio 17-4PH low, especially yield strength is very low; Meet hot strength, yield strength is high, corrosion resistance is good, does not have the material of magnetic to be generally high nitrogen stainless steel, and also the method for useful 17-4PH and 316L solid solution nitrogen improves material property, but density is low, anti-corrosion and the poor performance such as intensity.
Summary of the invention
The object of the invention is to provide a kind of MIM manufacturing process without magnetic 17-4PH stainless steel parts, to solve the problems referred to above of prior art.
The object of the invention is to be achieved through the following technical solutions.
Without a MIM manufacturing process for magnetic 17-4PH stainless steel parts, its step is as follows:
(1), by diameter be 7-10 micron 17-4PH powder of stainless steel with account for the binding agent that gross weight is 8-11% and be placed in kneader, at the temperature range mixing 30-120 minute of 175-195 DEG C;
(2), by after the compound cool to room temperature of preparation in step (1) use crusher in crushing, broken material in 160-190 DEG C of extrusion granulator, is convenient to injection moulding and is used in injector;
(3), injection moulding: by the feeding of preparation in step (2) in injection machine, with 160-210 DEG C, under injection pressure 60-140Mpa, mould temperature 70-150 DEG C condition, be processed into blank;
(4) blank of processing in step (3) is placed on 110-140 DEG C of catalysis degreasing 1-4 hour in catalysis degreasing stove, removes the polyformaldehyde in injection base;
(5) blank good for catalysis degreasing in step (4) is put into degreasing in vacuum drying oven, sintering, sintering process is: be heated to 600-800 DEG C from room temperature with the programming rate of 1-5 DEG C/min, insulation 30-120 minute; Be heated to 1260-1360 DEG C from 600-800 DEG C with the programming rate of 3-8 DEG C/min, insulation 60-180 minute, control protection atmospheric pressure 45-100KPa in stove in process, the cooling after terminating still keeps the pressure protecting gas.
(6) by the 1130-1160 DEG C of solution treatment in 1130-1160 DEG C of solution treatment or vacuum drying oven in the continuous oven of protection gas shielded of the part that sinters in step (5).
One in protection gas decomposed ammonia, nitrogen and argon gas used in sintering process in step (5) carries out negative pressure protection degreasing, pre-burning.
Described binding agent is that based binder moulded by polyformaldehyde, is made up of the following raw material according to weight percent meter: polyformaldehyde 80-89.5%, high-density polystyrene 4-10%, compatilizer EVA1-2.5%, paraffin 5-11%, antioxidant 0.5-1%.
The present invention adopts MIM technique 17-4PH powder to be sintered by nitrogen, then solution treatment obtain that compactness, corrosion resistance are good, hot strength and surrender high, non-magnetic MIM metal parts.
Detailed description of the invention
Technical characterstic of the present invention is set forth further below in conjunction with specific embodiment.
Embodiment 1: manufacture without magnetic 17-4PH stainless steel injection powder:
(1), by diameter be 7 microns 17-4PH powder of stainless steel with account for gross weight be 8% binding agent be placed in kneader, mix 40 minutes the temperature ranges of 175 DEG C;
(2), by after the compound cool to room temperature of preparation in step (1) use crusher in crushing, broken material in 160 DEG C of extrusion granulators, is convenient to injection moulding and is used in injector;
(3), injection moulding: by the feeding of preparation in step (2) in injection machine, with 160 DEG C, injection pressure 60Mpa, under mould temperature 70 DEG C of conditions, is processed into blank;
(4) blank of processing in step (3) to be placed in catalysis degreasing stove 110 DEG C of catalysis degreasings 2 hours, to remove the polyformaldehyde in injection base;
(5) blank good for catalysis degreasing in step (4) is put into degreasing in vacuum drying oven, sintering, sintering process is: be heated to 600 DEG C from room temperature with the programming rate of 2 DEG C/min, is incubated 120 minutes; Be heated to 1360 DEG C from 600 DEG C with the programming rate of 5 DEG C/min, be incubated 60 minutes, control nitrogen pressure in furnace 50KPa in process, the cooling after terminating still keeps the pressure of nitrogen; Negative pressure protection degreasing, pre-burning is carried out with nitrogen in sintering process.
(6) by the 1160 DEG C of solution treatment in 1130 DEG C of solution treatment or vacuum drying oven in the continuous oven of nitrogen protection of the part that sinters in step (5).
Embodiment 2
(1), by diameter be 9 microns 17-4PH powder of stainless steel with account for gross weight be 11% binding agent be placed in kneader, mix 120 minutes the temperature ranges of 195 DEG C;
(2), by after the compound cool to room temperature of preparation in step (1) use crusher in crushing, broken material in 180 DEG C of extrusion granulators, is convenient to injection moulding and is used in injector;
(3), injection moulding: by the feeding of preparation in step (2) in injection machine, with 180 DEG C, injection pressure 100Mpa, under mould temperature 100 DEG C of conditions, is processed into blank;
(4) blank of processing in step (3) to be placed in catalysis degreasing stove 110 DEG C of catalysis degreasings 4 hours, to remove the polyformaldehyde in injection base;
(5) blank good for catalysis degreasing in step (4) is put into degreasing in vacuum drying oven, sintering, sintering process is: be heated to 700 DEG C from room temperature with the programming rate of 2 DEG C/min, is incubated 80 minutes; Be heated to 1360 DEG C from 800 DEG C with the programming rate of 3-8 DEG C/min, be incubated 60 minutes, control nitrogen pressure in furnace 100KPa in process, the cooling after terminating still keeps the pressure of nitrogen; Negative pressure protection degreasing, pre-burning is carried out with decomposed ammonia in sintering process.
(6) 1160 DEG C of solution treatment in 1160 DEG C of solution treatment or vacuum drying oven in the continuous oven part sintered in step (5) protected at decomposed ammonia.
Embodiment 3
(1), by diameter be 10 microns 17-4PH powder of stainless steel with account for gross weight be 11% binding agent be placed in kneader, mix 120 minutes the temperature ranges of 195 DEG C;
(2), by after the compound cool to room temperature of preparation in step (1) use crusher in crushing, broken material in 190 DEG C of extrusion granulators, is convenient to injection moulding and is used in injector;
(3), injection moulding: by the feeding of preparation in step (2) in injection machine, with 210 DEG C, injection pressure 140Mpa, under mould temperature 150 DEG C of conditions, is processed into blank;
(4) blank of processing in step (3) to be placed in catalysis degreasing stove 140 DEG C of catalysis degreasings 4 hours, to remove the polyformaldehyde in injection base;
(5) blank good for catalysis degreasing in step (4) is put into degreasing in vacuum drying oven, sintering, sintering process is: be heated to 800 DEG C from room temperature with the programming rate of 5 DEG C/min, is incubated 50 minutes; Be heated to 1360 DEG C from 800 DEG C with the programming rate of 3 DEG C/min, be incubated 80 minutes, control decomposed ammonia atmospheric pressure 100KPa in stove in process, the cooling after terminating still keeps the pressure of decomposed ammonia.
(6) 1150 DEG C of solution treatment in 1150 DEG C of solution treatment or vacuum drying oven in the continuous oven part sintered in step (5) protected at decomposed ammonia.
Embodiment 4
Adopt the rotating camera shell that the present invention produces, more than density 7.6g/cm3, sintered dimensions precision is high, and product strength is high, corrosion resistance good, magnetic conductivity is low, meets the requirement of client completely.The performance of material of the present invention is that density is greater than 7.6g/cm3, hot strength is greater than 700MPa, yield strength is greater than 390MPa, percentage elongation is greater than 30%, magnetic conductivity is less than 1.03, and 35 DEG C of neutral salt spray tests are greater than 48 hours, overcomes the magnetic shortcoming of 17-4PH material common process, increase by more than 50% with 316L material phase specific tensile strength, yield strength increases by more than 1 times simultaneously; Suitable with the performance of HK30, but material price is cheap, and stability and the dimensional accuracy of sintering are high.
Embodiment 5
Adopt the mobile phone of the present invention's production without magnetic card holder, more than density 7.6g/cm3, sintered dimensions precision is high, and product strength is high, corrosion resistance good, product is nonmagnetic, meets the requirement of client completely.The performance of material of the present invention is that density is greater than 7.6g/cm3, hot strength is greater than 700MPa, yield strength is greater than 390MPa, percentage elongation is greater than 30%, and magnetic conductivity is less than 1.03, and 35 DEG C of neutral salt spray tests are greater than 48 hours, low and the magnetic shortcoming of 17-4PH material common process of the Kato intensity overcoming 316L materials processing, meet customer requirement Kato without magnetic, the requirement that anti-corrosion and intensity is high, material price is cheap simultaneously, and stability and the dimensional accuracy of sintering are high.
Embodiment 6
Adopt the rotating camera bonnet that the present invention produces, more than density 7.6g/cm3, percentage elongation is high, intensity good, and polishing is without hole, sand holes, overcome the shortcoming of the low yielding and low inconvenient shaping of 17-4PH percentage elongation of 316L intensity, well meet the instructions for use of client.