Wear of 42CrMo4 surface-treated steel for production agricultural machine parts by abrasive particles

Cilj ovog rada bio je analizirati ponašanje trošenja površinski oplemenjenog čelika 42CrMo4 gibanjem u masi abraziva u ovisnosti o brzini gibanja uzoraka te kutu sudara čestica abraziva i trošene površine. Uzorci za ispitivanje su površinski oplemenjeni postupcima toplinske obrade indukcijskog kaljenja i toplinskokemijskom obradom plinskog nitriranja. Indukcijsko kaljenje je toplinska obrada kojom se zakaljuju samo površinski slojevi predmeta, dok njegova jezgra zadrţava početnu strukturu. Plinsko nitriranje je postupak površinske toplinsko-kemijske obrade, odnosno ţarenje u sredstvu koje odaje dušik s ciljem da se dobije površina obogaćena dušikom i otporna na trošenje. Ispitivanje trošenja čelika 42CrMo4 provedeno je pomoću ureĎaja za ispitivanje trošenja uzoraka gibanjem u masi abraziva. Na uzorcima je provedeno i ispitivanje mikrotvrdoće po Vickers metodi. Najmanje trošenje kod obje vrste površinskog oplemenjivanja zabiljeţeno je pri najmanjom brzini gibanja uzoraka u masi abraziva od 1 m/s te pri većem kutu sudara trošene površine i čestica abraziva od 60°. Očekivano najveće trošenje u oba slučaja površinskog oplemenjivanja zabiljeţeno je pri najvećoj brzini gibanja uzoraka u masi abraziva od 2,5 m/s te pri manjem kutu sudara trošene površine i čestica abraziva od 30°. Plinski nitrirani uzorci pokazali su nešto bolje rezultate pri ispitivanju, odnosno manji prosječan gubitak mase u odnosu na indukcijski kaljene uzorke.The aim of this paper was to analyze the wear of surface-treated 42CrMo4 steel by motion in the abrasive mass depending on the velocity of the specimens and the collision angle of the abrasive particles and the worn surface. The test specimens were subjected to surface treatment processes of induction hardening and gas-nitriding. Induction hardening is a thermal process that hardens only the surface layers of an object, while the object’s core retains its initial structure. Gas nitriding is a process of surface thermal-chemical treatment, i.e., annealing in a medium that emits nitrogen to achieve a wear-resistant surface. The wear test of 42CrMo4 steel was performed using a device for testing the wear of samples by motion in the abrasive mass. The samples were also tested for microhardness by the Vickers method. The lowest wear in both processes was recorded at the lowest velocity of movement of samples in the abrasive, equaling to 1 m/s and at a higher collision angle of the worn surface and abrasive particles, equaling to 60°. The expected highest wear in both cases of surface treatments was recorded at the highest velocity of the movement of the samples in the abrasive mass, equaling to 2.5 m/s and at a lower angle of collision of the worn surface and abrasive particles, equaling to 30°. Gas-nitrided samples showed slightly better test results, i.e., lower average mass loss compared to induction hardened samples