Vpliv pogojev sfereoidizacijskega žarjenja na lastnosti jekla 42CrMo4

Pašić, Ermina (author), Nagode, Aleš (mentor)

Namen diplomskega dela je bil preučiti vpliv sferoidizacijskega žarjenja na trdoto in mikrostrukturo malolegiranega jekla za poboljšanje 42CrMo4. Za izvedbo sferoidizacijskega žarjenja v laboratorijskem okolju, so bili v proizvodnem procesu iz jeklene pločevine debeline 56 mm, najprej izrezani vzorci dimenzije 100 mm x 100 mm x 56 mm. Na jeklu v vroče valjanem stanju smo izvedli dilatometrsko analizo za določevanje premenskih temperatur Ac1 in Ac3, ki znašata 715 °C oz. 782 °C. Mikrostruktura jekla pred sferoidizacijskim žarjenjem je bila martenzitno-bainitna z območji lamelarnega perlita, povprečna trdota pa 288,8 HB. Jeklo smo sferoidizacijsko žarili pri 700 °C, čas žarjenja je bil od 1 ure do 24 ur. S časom sferoidizacijskega žarjenja se je stopnja sferoidizacije povečevala od 50 % po 1 in 2 urah žarjenja do 95 % pri 12 in 24 urah žarjenja. Prav tako se je s časom žarjenja zniževala trota in sicer od 233,2 HB po 1 uri žarjenja do 186,6 HB po 24 urah žarjenja. Zahtevano znižanje trdote pod 240 HB je bilo tako doseženo že po 1 uri sferoidizacijskega žarjenja.

• Language: Slovenian
• Keywords: jeklo 42CrMo4, sferoidizacijsko žarjenje, mikrostrukturna analiza, trdota, dilatometrija
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2018
• PID: 20.500.12556/RUL-105379
• COBISS.SI-ID: 1777759
• Publication date in RUL: 23.11.2018

Secondary language

• Language: English
• Title: The effect of spheroidisation annealing conditions on the properties of 42CrMo4 steel

Abstract

The purpose of the diploma work was to study the influence of spheroidisation annealing on the hardness and microstructure of steel 42CrMo4. In order to carry out the spheroidization annealing in a laboratory, samples of dimensions of 100 mm x 100 mm x 56 mm were cut from the steel plate of thickness of 56 mm. On the steel in hot-rolled conditions, a dilatometry was carried out for the determination of Ac1 and Ac3 transformation temperatures, which were determined to be715 °C and 782 °C, respectively. The microstructure of steel prior to sfereoidisation annealing was martensitic-bainitic with some areas of lamellar perlite. The average hardness was 288.8 HB. The steel was spheroidized at 700 °C, the time of sphereoidization annealing were from 1 hour to 24 hours. At the time of sporeoidization annealing, the degree of spheroidization increased from 50% after 1 and 2 hours to annealing up to 95% after 12 and 24 hours of annealing. Also, with the time of annealing, the hardness was reduced from 233.2 HB after 1 hour of annealing to 186.6 HB after 24 hours of annealing. The required reduction in hardness below 240 HB was achieved after 1 hour of spheroidisation annealing.

• Keywords: 42CrMo4 steel, sfereoidisation annealing, microstructural analysis, hardness, dilatometry