Sistem za kriogeno prisilno hlajenje kovinskih nanosov med procesom laserskega ciljnega nanašanja

Amon, Nejc (author), Govekar, Edvard (mentor)

V sklopu zaključne naloge smo nadgradili obstoječi sistem za lasersko ciljno nanašanje kovinskega prahu (DED-LB) s sistemom za kriogeno hlajenje z dušikom. Glavne komponente sistema za kriogeno hlajenje so Dewarjeva posoda z izstopnim ventilom, dovodne cevi in usmerjevalna šoba. Z nadgrajenim sistemom za DED-LB smo poleg nanosov brez hlajenja, z dovodom plinaste ali tekoče faze dušika v neposredno okolico talilnega bazena, izdelali nanose s tremi stopnjami hlajenja. Kot prašnati dodajani material in substrat smo uporabili nerjavno jeklo SS316L in SS304. Za spremljanje procesa DED-LB smo uporabili IR kamero. Karakterizacijo vpliva hlajenja nastalih nanosov smo ovrednotili z EBSD analizo velikosti kristalnih zrn in mikrotrdote po Vickersu. Rezultalti posnetkov IR kamere in analiz mikrostrukture so v nasprotju s pričakovanji pokazali, da z obstoječo izvedbo sistema kriogenega hlajenja ne dosežemo želenega ohlajanja in posledično manjše velikosti kristalnih zrn nastalih nanosov. Med izvedbami nanosov je bil manjši učinek zaznan samo v primeru dovoda tekoče faze dušika.

• Language: Slovenian
• Keywords: dodajalne tehnologije, lasersko nalaganje kovin, kriogeno hlajenje, tekoči dušik, mikrostruktura
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Year: 2025
• Number of pages: XII,41 f.
• PID: 20.500.12556/RUL-171828
• UDC: 621.791.72:621.762:62-712(043.2)
• COBISS.SI-ID: 248244483
• Publication date in RUL: 03.09.2025

Secondary language

• Language: English
• Title: System for cryogenic forced cooling of metal deposits during the laser direct energy deposition process

Abstract

As part of the final thesis, we upgraded the existing system for laser directed deposition of metallic powder (DED-LB) with a cryogenic cooling system using nitrogen. The main components of the cryogenic cooling system are a Dewar vessel with an outlet valve, supply tubes, and a directing nozzle. With the upgraded DED-LB system, in addition to deposits without cooling, we also produced deposits with three levels of cooling. Stainless steel SS316L and SS304 were used as the filler material and substrate. To monitor the DED-LB process, we used an IR camera. The effect of cooling on the resulting deposits was characterized by EBSD analysis of grain size and Vickers microhardness measurements. The results of the IR camera recordings and microstructure analyses, contrary to expectations, showed that with the current design of the cryogenic cooling system, the desired cooling and consequently smaller grain sizes of the resulting deposits were not achieved. The greatest effect on the deposits was a minor effect observed only in the case of supplying the liquid phase of nitrogen.

• Keywords: additive manufacturing, laser metal deposition, cryogenic cooling, liquid nitrogen, microstructure