Steel for cold working machine structures, and method for producing same

A technology of mechanical structure and manufacturing method, which is applied in the field of steel for cold working mechanical structure and its manufacturing, and can solve the problems of softness that has not been disclosed

Pending Publication Date: 2021-09-03
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, steel containing both Cr and Mo may be difficult to soften after spheroidizing annealing. However, Patent Docume...

Method used

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  • Steel for cold working machine structures, and method for producing same
  • Steel for cold working machine structures, and method for producing same
  • Steel for cold working machine structures, and method for producing same

Examples

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Effect test

Embodiment 1

[0128] Using steels with the chemical compositions shown in steel types A and D in Table 1, make A test piece for processing Formaster. Pressing and cooling were carried out with the Formaster test machine under the conditions described in Table 2 using the produced test piece for Formaster processing. Although not described in Table 2, in the cooling in the temperature range of 500° C. or lower, when the average cooling rate during the second cooling is 1° C. / second or more, the average cooling rate during the second cooling is cooled to around room temperature ( 25°C to 40°C), when the average cooling rate during the second cooling is lower than 1°C / s, gas quenching is adopted.

[0129] In Table 1 and Table 2, and Tables 3 to 5 described later, the underlined numerical values ​​indicate a range that deviates from the embodiment of the present invention. In addition, in the column of carbon equivalent of Table 1, the value calculated by following formula (1) is described. ...

Embodiment 2

[0179] Using steels having the chemical composition shown in steel types B and C in Table 1, rolling and cooling were carried out under the conditions in Table 4 on an actual rolling line. In addition, in the rolling line of the real machine, the heating furnace, roughing mill, intermediate rolling mill, intermediate water-cooled belt, wheel rolling mill, sizing rolling mill, product water-cooled belt, cooling conveyor and three-dimensional warehouse are connected in sequence. The processing is carried out with a rolling mill, the finishing is carried out with a sizing mill, and the first cooling and the second cooling are carried out by a cooling conveyor. Although not described in Table 4, the cooling in the temperature range of 500° C. or less was performed by cooling to about 400° C. at the average cooling rate during the second cooling, and then allowing to cool. Samples were taken from the obtained rolled material, and one of them was used as a sample without spheroidizi...

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Abstract

A steel for cold working machine structures, comprising 0.32 to 0.44% by mass of C, 0.15 to 0.35% by mass of Si, 0.55 to 0.95% by mass of Mn, 0.030% by mass or less of P, 0.030% by mass or less of S, 0.85 to 1.25% by mass of Cr, 0.15 to 0.35% by mass of Mo, 0.01 to 0.1% by mass of Al and a remainder made up by iron and unavoidable impurities, containing proeutectoid ferrite at an area ratio of 30 to 70% inclusive, and having an average ferrite crystal grain diameter of 5 to 15 [mu]m.

Description

technical field [0001] The present invention relates to steel for machine structural use for cold working and a manufacturing method thereof. Background technique [0002] When manufacturing various parts such as automobile parts and construction machine parts, hot-rolled materials such as carbon steel or alloy steel are generally subjected to spheroidizing annealing for the purpose of imparting cold workability. Then, the rolled material after the spheroidizing annealing is subjected to cold working, then subjected to machining such as cutting to form a predetermined shape, and then quenched and tempered to perform final strength adjustment. [0003] In recent years, the conditions of the spheroidizing annealing have been re-examined from the viewpoint of energy saving, and in particular, shortening of the spheroidizing annealing time has been demanded. If the treatment time for spheroidizing annealing is reduced by 20 to 30%, corresponding energy consumption, CO 2 reduct...

Claims

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Application Information

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IPC IPC(8): C21D8/06C22C38/50C22C38/00C22C38/22
CPCC22C38/22C22C38/42C22C38/44C22C38/28C22C38/26C22C38/001C21D8/0226C21D8/0263C21D8/0273C21D2211/009C21D2211/005
Inventor 山下浩司村上昌吾坂田昌之千叶政道
Owner KOBE STEEL LTD
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