CS262384B1 - Steel for castings with high toughness and abrasion resistance - Google Patents

Abstract

The solution relates to a wear-resistant casting steel, which is suitable for highly dynamically stressed machine parts exposed to intensive abrasive wear by a medium with hard particles. The abrasive wear-resistant casting steel contains, in a mass concentration, 0.30 to 0.40% carbon, 0.60 to 0.90% manganese, 0.20 to 0.50% silicon, 0.80 to 1.10% chromium, 0.90 to 1.25% nickel, 0.15 to 0.25% molybdenum, 0.01 to 0.028% phosphorus, 0.01 to 0.028% sulfur and the rest iron. It further contains, by weight, 0.01 to 0.05% titanium, 0.005 to 0.03% cerium, 0.005 to 0.03% calcium and 0.01 to 0.08% aluminum.

Description

BACKGROUND OF THE INVENTION The present invention relates to casting steel of high toughness and abrasive wear resistance, which is particularly suitable for the walls of cement mill mills, limestone grinder hammers and other highly stressed machine parts.

Up to now, low and medium alloyed under-eutectoid steels with sorbitol structure have been used for the production of highly dynamically loaded components subjected to abrasive wear. A disadvantage of said steels is that, after deoxidation with aluminum, brittle aluminum oxides in the form of sharp-edged non-metallic inclusions at the primary grain boundaries are eliminated.

At a higher nitrogen content, brittle aluminum nitrides are deposited at the primary grain boundary during heat treatment. In the heat-treated state at a hardness of 47 HRC with a sorbitic structure of -2, steels of low impact strength KCV = 0.07 to 0.15 MJ.m are achieved. As a result, after a certain period of operational use of the castings, the components crack, reducing their service life. The value of relative abrasive wear resistance is max. 1.7.

Above mentioned drawbacks are eliminated by abrasive wear resistant casting steel with high impact resistance and higher abrasive wear resistance, containing in the concentration of 0.30 to 0.40% carbon, 0.60 to 0.90% manganese, 0.20 to 0 50% silicon, 0.80-1.10% chromium, 0.90-1.25% nickel, 0.15-0.25% molybdenum, 0.01-0.028% phosphorus, 0.01-0.028% sulfur the remainder being iron according to the invention. It consists of a concentration of 0.01 to 0.05% by weight of titanium, 0.005 to 0.04% of cerium,

0.005 to 0.03% calcium and 0.01 to 0.08% aluminum.

The basic advantage of the cast steel according to the invention is the increased toughness caused by the non-metallic inclusions being dispersed in the structure and located within the grains.

Elimination of brittle oxides and nitrides at primary grain boundaries is completely eliminated. When hardening to 47 HRC hardness, the notch toughness value is increased to a value of KCV = _o = 0.200 to 0.300 MJ.m. Also, the value of relative abrasive wear resistance x is greater than 2.0 to 2.2.

The invention will now be described with reference to two exemplary embodiments.

Example 1

Abrasive wear resistant casting steel with high impact resistance, designed for the production of partition walls and hammers:

Element Mass concentration

carbon manganese silicon chromium nickel molybdenum phosphorus sulfur aluminum titanium calcium cer

0.37

0.85

0.44

1.09

1.16

0.22

0.024

0,025

0,070

0.050

0.030

0.012

Example 2 Carbon Manganese [wt%]

0.34

1.05

chrome 0.95 nickel 1,02 molybdenum 0.16 phosphorus 0,021 sulfur 0.019 aluminium 0,039 titanium 0,045 calcium 0.010 cer 0.015

Samples for laboratory tests and castings for operational tests were made from the above melts. Heat treatment: samples were annealed to 780 ° C for 4 h, cooled in an oven. Hardening: heating 830 ° C, cooled water. Tempering: heating 400 ° C, 3 h, followed by 2 cooling in water. Hardness 47 to 49 HRC, impact strength KCV = 0,215 to 0,280 MJ.m Flexural strength σ _ρ θ = 1 800 to 1 950 MPa. Relative wear resistance / CSN 01 5084 / JL = 2.0 = 2.2.

Claims (1)

SUBJECT OF THE INVENTION Steel for castings with high toughness and abrasive wear resistance, containing by weight 0,30 to 0,40% carbon, 0,60 to 0,90% manganese, 0,20 to 0,50% silicon, 0,80 to 0 1.10% chromium, 0.90-1.25% nickel, 0.15-0.25% molybdenum, 0.01 to 0.028% phosphorus, 0.01 to 0.028% sulfur and iron, characterized in that it contains 0.01 to 0.05% titanium by weight, 0.005 to 0.03% cerium, 0.005 to 0.03 % calcium and 0.01 to 0.08% aluminum.