The effect of boronizing and boro-chromizing on tribological performance of AISI 52100 bearing steels

Purpose - The purpose of this paper is to study the tribological behavior of hardened, boronized and boro-chromized AISI 52100 steel balls against boro-chromized AISI 1040 steel disk under 2, 5 and 10 N loads at 0.1 and 0.3 m/s sliding speeds. Design/methodology/approach - Boronizing treatment was realized at 1,000 degrees C for 2 h in a slurry salt bath consisting of borax, boric acid and ferrosilicon. Some of the boronized steels were chromized at 1,000 degrees C for 2 h by pack method in the powder mixture consisting of ferro-chromium, ammonium chloride and alumina. Similarly, AISI 1040 steel disk was boronized at 900 degrees C for 4 h in the same bath and then chromized by pack method. Friction and wear tests were carried out using a ball-on-disk machine. Findings - The results showed that the specific wear rate of hardened and boronized AISI 52100 steel balls decreased with increasing load and decreasing sliding speed. Untreated AISI 52100 steel balls showed much greater specific wear rate than the boronized and boro-chromized AISI 52100 steel balls. Boronized steel balls exhibited the highest wear resistance. The specific wear rates of hardened, boronized and borochromized steel balls were between 9.6422 x 10(-5) and 1.6714 x 10(-4), 4.4079 x 10(-6) and 3.2829 x 10(-5), and 1.0135 x 10(-5) and 3.0559 x 10(-5) mm(3) N-1 m(-1), respectively. The lowest coefficient of friction was recorded on a boro-chromized steel disk, tested against boronized steel ball at 0.3 m/s sliding speed and under low-load value. Research limitations/implications - Tests have been made on the basis of atmospheric conditions. The study can be detailed using some lubricants on the wear test. Practical implications - The research has shown that boronizing and boro-chromizing treatments realized on steels have a good wear resistance in the open atmosphere. Boronizing treatment has been used for tribological applications for a long time. Boro-chromizing treatment can be applied on steels, successfully. Originalitylvalue - Tribological properties of boro-chromized steels are explained in the present study for the first time.