Automated remanufacturing and upgrading of large industrial equipment
Gómez Fernández, Andrea (2020)
2020
Master's Programme in Materials Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2020-10-06
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202009247112
https://urn.fi/URN:NBN:fi:tuni-202009247112
Tiivistelmä
The objective of this master's thesis is to remanuracture and upgrade a worn area of large industrial equipment that has suffered from wear and corrosion, using an inexpensive directed energy deposition (DED) process called wire + arc additive manufacturing (WAAM).
Cold Metal Transfer (CMT) WAAM technique is used to build-up the component back to the original dimensions. To evaluate the amount of wear and estimate the magnitude of pre-machining, the worn-off area was first 3D laser scanned and compared to the original part by using a 3D CAD model. The worn area was machined and welded with filler and hard-facing alloy in order to obtain a new piece that is strong enough to perform the desired work. The filler alloy was high-strength low alloy steel (HSLA). The hard-facing alloy candidates consisted of various Fe-based and WC/W2 C- reinforced Ni-based alloys.
Tensile tests were carried out to validate the adhesion between the base material made of case hardening steel and filler metal. High-stress dry-pot impact-erosion wear tests using coarse granite abrasives were made to prove and validate the hard-facing alloys' wear resistance with respect to case-hardened steel.
According to the mechanical tests, heat-affected zone (HAZ) and fusion line between the base material and filler alloy survived the tensile tests withouth fracture. The fracture took place in the welded filler alloy indicating the weakest zone in the remanufactured component. The best hard-facing alloys outpferformed the case-hardened steel in wear tests.
Once the best hard-facing alloy was selected, a replica was welded and finally inspected with the 3D laser scanner to guarantee the desired dimensions.
Cold Metal Transfer (CMT) WAAM technique is used to build-up the component back to the original dimensions. To evaluate the amount of wear and estimate the magnitude of pre-machining, the worn-off area was first 3D laser scanned and compared to the original part by using a 3D CAD model. The worn area was machined and welded with filler and hard-facing alloy in order to obtain a new piece that is strong enough to perform the desired work. The filler alloy was high-strength low alloy steel (HSLA). The hard-facing alloy candidates consisted of various Fe-based and WC/W2 C- reinforced Ni-based alloys.
Tensile tests were carried out to validate the adhesion between the base material made of case hardening steel and filler metal. High-stress dry-pot impact-erosion wear tests using coarse granite abrasives were made to prove and validate the hard-facing alloys' wear resistance with respect to case-hardened steel.
According to the mechanical tests, heat-affected zone (HAZ) and fusion line between the base material and filler alloy survived the tensile tests withouth fracture. The fracture took place in the welded filler alloy indicating the weakest zone in the remanufactured component. The best hard-facing alloys outpferformed the case-hardened steel in wear tests.
Once the best hard-facing alloy was selected, a replica was welded and finally inspected with the 3D laser scanner to guarantee the desired dimensions.