Ndi mitundu yanji ya njira zochizira kutentha zothetsa zida?

(1) Kuzimitsa madzi

Kuzimitsa kwamadzi amodzi ndi njira yozimitsira momwe chogwirira ntchito cha austenitic chimamizidwa mwachangu m’malo ena ozizimitsa ndikuzimitsidwa mpaka kutentha. Kusankhidwa kwa sing’anga imodzi yamadzimadzi yozimitsa kuzirala kumachokera ku mfundo yakuti kuzizira kwa workpiece mu sing’anga iyi kuyenera kukhala yaikulu kuposa kuzizira kwambiri kwazitsulo zazitsulo, ndipo workpiece sayenera kuzimitsidwa ndi kusweka. Njira zozimitsira zamadzimadzi zimodzi zimaphatikiza madzi, brine, madzi amchere, mafuta, ndi zina zomwe zimapangidwa mwapadera zozimitsa madzi.

(2) Kuzimitsa madzi kawiri

In order to overcome the shortcomings of single-liquid quenching and make the quenching and cooling of the workpiece as close to the ideal situation as possible, two media with different cooling capacities can be used together, that is, the heated workpiece is quenched into the first medium with large cooling capacity, and cooled to a slightly lower temperature. Above Ms temperature (about 300), then immediately transferred to a second medium with less cooling capacity to cool to room temperature. This quenching cooling method is called double liquid quenching. For some workpieces, in order to further slow down the cooling rate below Ms, water quenching air cooling or oil quenching air cooling can also be used, and air can also be used as a cooling medium.

(3) Kuzimitsa kwapang’onopang’ono (kuzimitsa kwa martensite)

The characteristic of this cooling method is that the workpiece is first immersed in a molten pool with a temperature slightly higher than Ms, and then kept in the molten pool until the surface and center of the workpiece cool to the temperature of the molten pool, and then taken out for air cooling. The bath temperature is generally 10 to 20. The medium in the bath consists of nitrate bath, alkali bath and neutral salt bath.

(4) Pre-cooling and quenching

After high-frequency quenching, the workpiece is not immersed in the cooling medium immediately, but is cooled in the air for a short time, and then immersed in the cooling medium after the workpiece is cooled to a certain temperature. This quenching method is called pre-cooling quenching or delayed quenching.

Chinsinsi cha kuziziritsa chisanadze ndikuwongolera nthawi yoziziritsa, ndipo zotsatira za nthawi yaifupi yozizirirapo ndizosauka. Kutalika kwa nthawi kumatha kuchepetsa kuuma kozimitsa kwa chogwirira ntchito (kusintha kosasintha kwa martensitic). Chifukwa cha zipangizo zosiyanasiyana, akalumikidzidwa ndi makulidwe workpieces, komanso chikoka cha ng’anjo kutentha ndi yozungulira kutentha, chisanadze kuzirala nthawi yovuta kuwerengera molondola ndipo makamaka zimadalira luso ndi zinachitikira woyendetsa.

(5) Kuzimitsidwa kwanuko

Zina zogwirira ntchito zimangofunika gawo limodzi kuti likhale lolimba kwambiri, ndipo mbali zina zilibe zofunikira zolimba kapena zimafuna kuuma kochepa. Pachifukwa ichi, njira yozimitsira m’deralo ingagwiritsidwe ntchito, ndiko kuti, gawo linalake la workpiece lizimitsidwa. Pali mitundu iwiri ikuluikulu yozimitsa m’deralo: kutenthetsa m’deralo ndi kuziziritsa kwapafupi ndi kutentha kwakukulu ndi kuziziritsa kwanuko. Yoyambayo ndi yabwino kwambiri yopangira zida zotenthetsera m’ng’anjo zosambira zamchere, pomwe zotsirizirazi zitha kugwiritsidwa ntchito m’ng’anjo zamabokosi ndi ng’anjo zosambira zamchere.

(6) Kuzizira

Chimfine mankhwala ndi pambuyo kuzimitsa ntchito imene kuzimitsidwa zitsulo mosalekeza utakhazikika kutentha pansi firiji kutentha, kotero kuti untransformed anapitiriza austenite kutentha firiji mosalekeza kusandulika martensite.

For some parts with high dimensional stability, it is necessary to reduce the retained austenite in the quenched structure to the lowest temperature, so as to avoid failure due to changes in shape and size exceeding the accuracy requirements during use. That’s what cold processing is for. The cold treatment temperature is mainly determined according to the Ms point of the steel, combined with the technical requirements of the parts, process equipment conditions and other factors. After the quenched workpiece is cooled to room temperature, it must be cold-treated immediately, otherwise its effect will be affected. The cold treatment of small and medium pieces is generally maintained for 1 to 3 hours, and should be slowly heated in the air after treatment. When the workpiece is heated to room temperature, it should be tempered immediately, which can effectively prevent the workpiece from cracking.