Narrow-hardenability pinion steel and preparation method thereof

Abstract

The invention provides a narrow-hardenability pinion steel which comprises the following components in percentage by weight: 0.18%-0.22% of C, 0.20%-0.30% of Si, 0.90%-1.15% of Mn, less than or equal to 0.030% of P, less than or equal to 0.030% of S, 1.00%-1.35% of Cr, 0.04%-0.08% of Ti, 0.004%-0.005% of B, 0.025%-0.038% of W, less than or equal to 11.5*10<-6> of [O], less than or equal to 1.5*10<-6> of [H], 35*10<-6>-45*10<-6> of [N] and the balance of Fe and inevitable impurities. The invention provides a preparation method of the narrow-hardenability pinion steel. The preparation method comprises the following steps: 1) primary smelting based on a top-bottom blowing converter; 2) ladle deoxidizing and alloying; 3) LF (ladle furnace) refining; 4) RH refining; and 5) continuous casting. Compared with the prior art, the narrow-hardenability pinion steel provided by the invention has the characteristics of better wear resistance and high temperature resistance, higher hardenability andnarrower jominy hardenability.

Description

technical field [0001] The invention belongs to the field of material preparation, in particular to a narrow hardenability gear steel and a preparation method thereof. Background technique [0002] Gear steel has a high-carbon wear-resistant surface layer and a low-carbon high-strength toughness core, so that it can withstand huge impact loads, contact stress and wear. When this steel is applied, it should usually meet the two requirements of processability and usability. basic requirements. Research and development of high-performance gear steel is receiving increasing attention. [0003] Gear steel is one of the key materials used in a large amount of automotive materials and has high requirements. It not only affects the technical and economic indicators such as vehicle life and energy consumption, but is also crucial to meeting safety, environmental protection and comfort requirements. The vigorous development of my country's automobile industry has not only greatly in...

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Problems solved by technology

[0005] However, the end hardenability bandwidth of the prior art gear steel, such as: Chinese patent application number is 201110156328.9, the application date is June 10, 2011, and the name of the invention is: a high-strength, high-toughness, corrosion-resistant, high-temperature bearing gear steel and its preparation The patent application of the method, the weight percentage distribution of the chemical elements of the bearing gear steel disclosed in the patent application is: C: 0.10%~0.22%, Mn: ≤0.5%, Si: ≤0.5%, Cr: 12.0%~15.0%, Ni : 1.50%~3.00%, Mo: 4.00%~6.00%, V: 0.50%~0.90%, Co: 12.0%~15.0%, W: 0.30%~2.00%, Nb: 0.02%~0.08%, of which: V / Nb: 25~35, Mo / W: 6~12, Co / Mo: 2~3, Cr+6Si+4Mo+1.5W+11V+5Nb≤52%, 40C+2Mn+4Ni+30N+2Co≥42 %, [O]+[N]+[H]≤0.0040%, the balance is Fe and unavoidable impurities; the process is: composition ratio and control→vacuum smelting→steel ingot thermal processing→steel surface hardening treatment→ Although the heat treatment of steel can meet the requirements of bearing gear steel that is subjected to high temperature and corrosive environment during service, the end hardenability is wide and the Cr content is high, which makes the production cost higher