High-grade structural steel with bainitic structure, forged part produced therefrom and method for producing a forged part

A technology of microstructure and structural steel, applied in the field of forgings, can solve problems such as inapplicability, and achieve the effect of small residual stress and small difference in hardness

Active Publication Date: 2018-08-31
DEUTSCHE EDELSTAHLWERKE GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Practical tests with steels of the aforementioned type have shown that this bainitic steel is not suitable for c

Method used

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  • High-grade structural steel with bainitic structure, forged part produced therefrom and method for producing a forged part
  • High-grade structural steel with bainitic structure, forged part produced therefrom and method for producing a forged part
  • High-grade structural steel with bainitic structure, forged part produced therefrom and method for producing a forged part

Examples

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Embodiment Construction

[0055] Next, the present invention will be further described according to the examples.

[0056] The molten steels E1-E6 according to the invention and the comparative melt V1 with the composition shown in Table 1 were melted and cast into semi-finished products which are ingots as they are usually provided for further processing in forging technology.

[0057] The semi-finished product is fully heated to the heating temperature for forging, and then hot-formed into a forged workpiece by die forging in a traditional way and then cooled to room temperature in air. Some of the forgings produced were subsequently tempered.

[0058] Table 2 shows the heating temperature Tw applied in the example, the t8 / 5 time necessary for passing through the critical temperature range of 800-500 °C, the temperature of the tempering treatment and the temperature of the tempering treatment if carried out Duration, as well as the proportion of bainite in the microstructure, the tensile strength Rm...

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Abstract

The invention provides a steel, which has a high strength, without complex heat treatment processes having to be performed for this purpose, and at the same time has a low tendency to warp. For this purpose, the high-grade structural steel according to the invention consists of (in % by weight) up to 0.25% C, up to 0.45% Si, 0.20-2.00% Mn; up to 4.00% Cr, 0.6-3.0% Mo, 0.004-0.020% N, up to 0.40% S, 0.001-0.035% Al, 0.0005-0.0025% B, up to 0.015% Nb, up to 0.01% Ti, up to 0.10% V, up to 1.5% Ni and up to 2.0% Cu, the remainder iron and unavoidable impurities, wherein the Al content %Al, the Nbcontent %Nb, the Ti content %Ti, the V content %V and the N content %N of the high-grade structural steel respectively meet the following condition: %Al/27 + %Nb/45 + %Ti/48 + %V/25 > %N/3.75. The high-grade structural steel according to the invention has a yield strength of at least 750 MPa, a tensile strength of at least 950 MPa and an organization structure which consists at least 80% by volumeof bainite and in total at most 20% by volume of residual austenite, ferrite, pearlite and/or martensite. On account of its combination of properties, the steel according to the invention is suitablein particular for the production of forged parts with great changes in cross section over its length. The invention also discloses a method for producing such forged components.

Description

technical field [0001] The invention relates to a high-quality structural steel with high strength and a microstructure of at least 80% by volume consisting of bainite. [0002] Furthermore, the invention relates to a forged part produced from such a high-quality structural steel. [0003] Finally, the invention relates to a method for producing forgings from the high-quality structural steel according to the invention. [0004] Where subsequent "%" data are given with respect to alloy or steel composition, these data refer to weight in each case, unless expressly stated otherwise. [0005] All mechanical properties given in this description of the steels according to the invention and possibly of the steels mentioned for comparison are determined in accordance with DIN EN ISO 6892-1, unless otherwise stated. Background technique [0006] As reported by engineers Christoph Keul et al. in the article "Entwicklung eines hochfestenduktilen bainitischen (HDB) Stahls für hochbe...

Claims

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Application Information

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IPC IPC(8): C21D1/02C21D1/20C22C38/00C22C38/02C22C38/04C22C38/12C22C38/18C22C38/22C22C38/38
CPCC21D1/20C21D7/13C21D2211/002C21D2211/008C22C38/001C22C38/02C22C38/04C22C38/06C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C21D1/02C22C38/12C22C38/14C21D8/00C22C38/58
Inventor 乌尔里希·赖歇尔蒂尔·施奈德斯弗兰克·范索斯特汉斯-京特·克鲁尔
Owner DEUTSCHE EDELSTAHLWERKE GMBH
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