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500MPa-grade steel for engineering machinery, and manufacturing method thereof

A technology of construction machinery and manufacturing methods, applied in the field of alloy steel, can solve the problems of high alloy cost, unstable performance, large blanking deformation, etc., and achieve the effects of improving strength and toughness, grain refinement, and fatigue life

Active Publication Date: 2018-09-14
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The steel plate has problems such as high alloy cost, poor plate shape, unstable performance, and large blanking deformation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 2

[0049] Example 2, 10mm specification Q500E steel plate, including the following mass percentage components C: 0.15%, Si: 0.23%, Mn: 1.49%, P: 0.013%, S: 0.005%, Cr: 0.17%, V: 0.033% , Ti: 0.016%, B: 0.0011%, and the balance is Fe and unavoidable impurities. After alloying deoxidation in steelmaking, LF refining for 30 minutes, RH vacuum refining and degassing for 25 minutes, so that the nitrogen content of molten steel is not higher than 38ppm, the hydrogen content is not higher than 1.5ppm, and the oxygen content is not higher than 20ppm; slab continuous casting, drawing Speed ​​1.2m / min; reheating for 4.0h to make the core temperature of the slab reach 1180°C, start rolling temperature 1140°C, second-stage rolling 900°C, finish rolling temperature 850°C, reduction rate 65%; steel plate reddening temperature 680°C ; straightening 5mm / m; quenching temperature 900 ℃, tempering temperature 650 ℃. Mechanical Properties Yield strength 545MPa, tensile strength 650MPa, elongation 2...

Embodiment 3

[0050] Example 3, 22mm specification Q500E, including the following mass percentage components C: 0.16%, Si: 0.20%, Mn: 1.33%, P: 0.013%, S: 0.005%, Ni: 0.20%, Nb: 0.026%, Ti: 0.016%, B: 0.0011%, and the balance is Fe and unavoidable impurities. After alloying deoxidation in steelmaking, LF refining for 26 minutes, RH vacuum refining and degassing for 29 minutes, so that the nitrogen content of molten steel is not higher than 38ppm, the hydrogen content is not higher than 1.5ppm, and the oxygen content is not higher than 20ppm; slab continuous casting, drawing Speed ​​1.2m / min; reheat for 4.2h to make the core temperature of the slab reach 1190°C, start rolling temperature 1140°C, second-stage rolling 950°C, finish rolling temperature 850°C, reduction rate 65%; steel plate reddening temperature 690°C ; straightening 6mm / m; quenching temperature 900 ℃, tempering temperature 640 ℃. Mechanical properties Yield strength 530MPa, tensile strength 645MPa, elongation 22%, impact ener...

Embodiment 4

[0051] Example 4, 8mm specification Q500E, including the following mass percentage components C: 0.15%, Si: 0.23%, Mn: 1.26%, P: 0.013%, S: 0.005%, Mo: 0.17%, Al: 0.027%, The balance is Fe and unavoidable impurities. After alloying deoxidation in steelmaking, LF refining for 28 minutes, RH vacuum refining and degassing for 28 minutes, so that the nitrogen content of molten steel is not higher than 38ppm, the hydrogen content is not higher than 1.5ppm, and the oxygen content is not higher than 20ppm; slab continuous casting, drawing Speed ​​1.0m / min; reheating for 4.0h to make the core temperature of the slab reach 1175°C, start rolling temperature 1130°C, second-stage rolling 920°C, finish rolling temperature 870°C, reduction rate 76%; steel plate reddening temperature 690°C ; straightening 6mm / m; quenching temperature 910 ℃, tempering temperature 640 ℃. Mechanical properties Yield strength 540MPa, tensile strength 660MPa, elongation 19%, impact energy at -40°C 86J, 86J, 83J ...

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Abstract

The invention discloses 500MPa-grade steel for engineering machinery, and a manufacturing method thereof. The steel grade is prepared from the following components in percentage by mass: 0.12 to 0.23percent of C, 0.10 to 0.60 percent of Si, 0.80 to 1.90 percent of Mn, less than 0.018 percent of P, less than 0.010 percent of S, one or multiple selected from 0 to 0.50 percent of Cr, 0 to 0.60 percent of Ni, 0 to 0.45 percent of Mo, 0 to 0.40 percent of Cu, 0 to 0.060 percent of Nb, 0 to 0.15 percent of V, 0 to 0.12 percent of Ti, 0 to 0.0030 percent of B and 0.010 to 0.050 percent of Al, and the balance Fe and inevitable impurities. A metallographic structure of the 500MPa-grade steel is a uniform and fine martensite high-temperature tempering structure, so that the 500MPa-grade steel has favorable mechanical property and fatigue performance. The fatigue life is remarkably prolonged compared with an existing engineering machinery steel grade.

Description

technical field [0001] The invention relates to an alloy steel technology, in particular to a 500MPa grade engineering machinery steel and a manufacturing method thereof. Background technique [0002] At present, two types of steel are basically used for construction machinery, Q235B and SS400, such as excavator arm sticks, loader arms, etc. Its yield strength is 235MPa, which meets the normal temperature impact performance, and its service life is within 30000h. Its yield strength and fatigue life are obviously insufficient. [0003] The application number is 201310289099.7, and the Chinese patent titled "a 500MPa ultra-fine grain steel for construction machinery and its manufacturing method" discloses a steel for construction machinery with a yield strength exceeding 500MPa, and its C content is 0.04-0.08%. It is not conducive to the formation of quenched martensite. The steel plate has problems such as high alloy cost, poor shape, unstable performance, large blanking d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/20C22C38/24C22C38/26C22C38/28C22C38/32C22C33/04C21D1/18C21D8/02C21D9/00
CPCC21D1/18C21D8/0226C21D9/0081C22C33/04C22C38/002C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/20C22C38/24C22C38/26C22C38/28C22C38/32C22C38/38
Inventor 冯勇吴俊平谯明亮李明霍松波刘继宏翟冬雨潘中德
Owner NANJING IRON & STEEL CO LTD