METHOD OF THERMAL TREATMENT OF A HIGH-STRENGTH WEAR-RESISTANT STEEL MOULDING (VARIANTS)

摘要

FIELD: metallurgy.;SUBSTANCE: invention relates to the area of metallurgy, namely to thermal treatment of high-strength wear-resistant steel mouldings used in manufacture of bucket teeth and excavator wheels operating in a shock-abrasive environment in various climatic zones. The moulding is made of steel containing, wt.%: carbon 0.38 to 0.45, silicon 0.20 to 0.45, manganese 0.80 to 1.20, chromium 2.20 to 3.00, nickel 2.15 to 3.50, molybdenum 0.25 to 0.50, vanadium 0.08 to 0.10, copper ≤0.30, calcium 0.005 to 0.01, cerium 0.005 to 0.01, aluminium 0.008 to 0.05 , niobium 0.008 to 0.10, zirconium 0.008 to 0.10, titanium 0.03 to 0.08, barium 0.005 to 0.01, boron 0.001 to 0.003, nitrogen 0.008 to 0.025, iron the rest, wherein the ratio of the total content of vanadium, niobium, titanium and zirconium to the carbon content is 0.52 to 0.84, and the aluminium content to the nitrogen content 1 to 2. The moulding is normalised at a temperature of 950 to 970°C for 4 hours, air-cooled to a temperature of 20°C and further heated to a temperature of 650 to 670°C sustained for 6 hours and air-cooled. Hardening in water is executed after heating to a temperature of 890 to 920°С and sustaining for 2.5 to 3.0 min per 1 mm of the moulding cross-section. Then triple austenitisation is executed at a temperature of Ac₁ + 5 to 10°C with sustaining at each cycle for 5 minutes and cooling in water. The subsequent tempering is executed at a temperature of 200 to 220°C or 570 to 580°C for 5 to 6 hours with air cooling.;EFFECT: hardness, wear resistance and impact resilience of mouldings are increased.;3 cl, 2 tbl