Nedfrysing av løp??

[Guest]

Var ikke helt sikker på hvor jeg skulle legge denne tråden, men jeg prøver

 

Hørte en gang om noe med ned frysing av løp, det skulle vist gi bedre presisjon. Noen som vet noe mer om dette? Hilken funksjon hadde det? Hva skjedde med løpet når det ble nedfryst?

[POS]

xxxxx xxxxx xxxxx xxxxx xxxxx

Edited October 24, 2010 by Guest

[350 Rem mag]

Enkelt, kjøle ned stålet med flytende nitrogen. Jeg tror dette er mest mumbo-jumbo, men det er nå så.

Søk på Google etter "cryogenic barrel" og du får ørten treff.

 

Her er litt info fra Lilja:

 

Q. What is your opinion of the deep cryogenic processing of barrels?

A. The cryogenic treating of barrels at a temperature of -300 degrees below zero has been a hot topic of discussion lately. Our short answer is that it will not harm your barrel but we are not completely convinced of all of the benefits claimed by some. The only benefits that we feel are likely to result from the treatment are possibly a longer barrel life and a slight increase in machinability.

 

Claims for increased accuracy through stress relief are not founded in our opinion. When barrels are button rifled no material is removed, it is just displaced. This causes stresses to be formed in the steel. If these stresses are not removed problems will result. These negative conditions include warping of the barrel during other machining operations, an increase in the bore diameter towards the muzzle end of the barrel during the contouring phase, and in the extreme, lengthwise splitting of the barrel. Also, if there are stresses remaining in the barrel they can be slowly released as a barrel warms up during firing. This causes the barrel to actually move during the course of shooting, causing inaccuracy.

 

In our testing we have found that the only effective means to completely remove the types of stresses introduced during rifling are with conventional heat treating using elevated temperatures. The -300 degree treatment alone will not remove these stresses. We have been told by a knowledgeable metallurgist that the deep cold treatment will, at best, remove up to 6% of the remaining stresses in the type of steel used for rifle barrels. The key words here are remaining stresses. In other words if the barrel was not stress relieved conventionally, then only 6% of the original stress will be removed. If the barrel has been treated conventionally with heat and then brought through the -300 degree cycle, up to 6% of any remaining stresses could be removed by the cold treatment. We do know through our testing that the cold treatment alone will not remove any significant amount of stress and that the problems outlined above concerning stress will remain in the barrel.

 

So, because of the very limited amount of stress that could be removed with the cold treatment (if the barrel has been properly stress relieved with heat as our barrels are) we do not believe that there can be much if any accuracy benefit to the -300 degree treatment of our barrels. It is for these reasons that we feel the cold process has very little potential for increasing the accuracy of our barrels. In our opinion, other than the removal of these stresses, there are no other mechanical factors involved that could benefit accuracy in a rifle barrel, resulting from a heat treating operation, either hot or cold.

 

For reasons not completely understood however there may be an increase in the wear resistance of the steel. This type of wear however does not contribute greatly to barrel erosion. We invite you to read our comments on this type of barrel wear in the question regarding the use of moly coated bullets.

 

Another possible side benefit to the freezing process is a slight increase in its machinability.