SU1392140A1 - Steel - Google Patents

Abstract

The invention relates to the field of metallurgy, in particular, to cement structural steels for the manufacture of paws and drill bits. The purpose of the invention is to improve manufacturability during casting, contact endurance and brittle fracture resistance. Steel contains, in May.%: Carbon 0.12-0.25; silicon 0.15-0.40; manganese 0.40-1.20; chromium 0.40-1.20; nickel 2.50-3.50; molybdenum 0.01-0.20; vanadium 0.05-0.15; calcium 0.002 - 0.02; zirconium 0.02-0.05; aluminum 0.01-0.05; cerium 0.001-0.01; lanthanum 0.001-0.005; praseodymium 0.0005-0.002; Neodymium 0.0005-0.002; iron - the rest. 2 tab. from 9 (L

Description

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The invention relates to metallurgy, in particular, to the search for cement constructional steels for the manufacture of drill bits and roller cones, with

The purpose of the invention is to increase the manufacturability, resistance to brittle fracture and contact endurance of steel.

Cemented structural steel was tested. Experimental fusions were made in a 30-tonne main arc furnace, silicocalcium, silico-zirconium, silicon metal were placed on the bottom of the ladle before release; the finished 15 | steel was cast on a semi-continuous steel casting plant on an electric section of 360 360 mm, then melted on an electro-slag OKB11-55A installation into ingots with a mass of 3.5 tons. Ingots were rolled to grade 105 mm in diameter

Determination of temporal resistance (strength limit Gg) of the air. Contact durability (NjQ) GOST 25501-78 was studied after chemical heat treatment. The processability of steel during casting was characterized by casting time.

Test data indicate a significant increase in the stability of hardenability (6-7 HRCg oscillation range is 2 times smaller), a higher (by 20-30%) level of brittle fracture resistance and contact endurance with high processability.

Claims (2)

Invention Formula Steel containing carbon, silica, manganese, chromium, nickel, molybdenum, vanadium, aluminum, calcium, cerium, lanthanum, neodymium and iron, with the aim of improving processability at They were cast on specimens of type W 1497-25 casting, contact endurance and 73 after quenching in oil with a temperature resistant to brittle fracture. : swarm and leave at-within 3 h. Impact strength (KCV) to the work of propagation of cracks (QD) was determined according to GOST 9454-78 on samples Qf S 10 35 mm with a V-shaped stress tensor. I The chemical composition and properties of the proposed and known steel are given in table. 1 and 2. The steel prokalaivability was determined according to GOST 5657-69, the tendency to brittle fracture j (propagation work 1, 1 and CT cracks according to GOST 9454-78) was investigated after thermal treatment according to the following mode: 1- | hardening at 880-900 ° C to oil, 2- quenching at 770-780 ° C to oil, tempering at 180-200 s and cooling to it additionally contains zirconium - and praseodymium in the following ratio of components, wt.%: 35 40 Carbon Silicon Manganese Chromium Nickel Molybdenum Vanadium Aluminum Calcium Cerium Lanthanum Neodymium Praseodymium Zirconium Iron 0.12-0.25 0.15-0.40 0.40-1.20 0.40-1.20 2.50-3.50 0.01-0.20 0.05-0.15 0 , 01-0.05 0.002-0.02 0.001-0.01 0.001-0.005 0.0005-0.002 0.0005-0.002 0.02-0.05 Else the air. Contact durability (NjQ) GOST 25501-78 was studied after chemical heat treatment. The processability of steel during casting was characterized by casting time. Test data indicate a significant increase in the stability of hardenability (6-7 HRCg oscillation range is 2 times smaller), a higher (by 20-30%) level of brittle fracture resistance and contact endurance with high processability. Invention Formula it additionally contains zirconium - and praseodymium in the following ratio of components, wt.%: about five 0 Carbon Silicon Manganese Chromium Nickel Molybdenum Vanadium Aluminum Calcium Cerium Lanthanum Neodymium Praseodymium Zirconium Iron 0.12-0.25 0.15-0.40 0.40-1.20 0.40-1.20 2.50-3.50 0.01-0.20 0.05-0.15 0 , 01-0.05 0.002-0.02 0.001-0.01 0.001-0.005 0.0005-0.002 0.0005-0.002 0.02-0.05 Else table 2