Steel for heat treatment
A quality and element technology, applied in the field of high-strength and high-toughness heat-treated steel, which can solve the problems of difficulty in heat-treating steel, complicated manufacturing process and high cost
Inactive Publication Date: 2013-01-30
KOBE STEEL LTD
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- Abstract
- Description
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- Application Information
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Problems solved by technology
[0014] However, the technology described in Patent Document 1 has the problems of high cost and complicated manufacturing process because the steel for heat treatment needs to increase the amount of alloying elements added.
[0015] The technology described in Patent Document 2 has a problem that the manufacturing process is complicated because processing such as wire drawing, cold rolling, cold forging, and quenching and tempering must be performed under specific conditions.
[0016] The technique described in Patent Document 3 has the problem of complicated manufacturing process because it needs to increase the temperature increase rate and shorten the retention time.
[0017] Moreover, the technologies described in Patent Documents 1 to 3 all require quenching and tempering under specific conditions after hot rolling is completed.
That is, it is necessary to carry out quenching and caulking under such specific conditions in the customer's factory after delivery to the customer, so there is a problem that it is difficult to manufacture high-strength and high-toughness steel for heat treatment
Method used
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Experimental program
Comparison scheme
Effect test
Embodiment
[0113] Next, an example that satisfies the requirements of the present invention is compared with a comparative example that does not meet the requirements of the present invention, so as to illustrate the effect of the present invention.
[0114] First, the alloy composition shown in Table 1 was melted in a small melting furnace and cast, and the soaking billet and hot rolling were carried out under the conditions shown in Table 2 to obtain the plate thickness of Examples 1-22 and Comparative Examples 1-6. Billet. Using these billets, quenching and tempering (heat treatment) were performed under the conditions shown in Table 2.
[0115] [Table 1]
[0116]
[0117] [Table 2]
[0118]
[0119] For the steel slabs of Examples 1 to 22 and Comparative Examples 1 to 6 produced under the conditions shown in Table 1 and Table 2, the value TH after hot rolling (the amount of Ti and Nb contained in the precipitate of 5 to 100 nm ), grain diameter (μm) and hardness Hv. In addition, evaluate ...
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Abstract
A steel for heat treatment, which exhibits high strength and high toughness even when the heat treatment (such as quenching and tempering) of the steel is conducted under conventional conditions in an after stage. The steel for heat treatment contains C: 0.10 to 0.70 mass %, Mn: 0.1 to 3.0 mass %, Al: 0.005 to 2.0 mass %, P: 0.050 mass % or less, S: 0.50 mass % or less, O: 0.0030 mass or less, N: 0.0200 mass % or less, and one or more selected from the group consisting of Ti: 0.30 mass % or less and Nb: 0.30 mass or less with the balance being Fe and unavoidable impurities, and has a TH value of 1.0 or above as calculated according to the formula: ({Ti} / 48+{Nb} / 93) 104 and grain diameters of 10 μm or below. {Ti} and {Nb} refer respectively to the contents of Ti and Nb in precipitates of 5 to 100 nm in size as determined about their respective extraction residues.
Description
Technical field [0001] The present invention relates to steel for heat treatment used in the manufacture of structural materials used for transportation machinery such as automobiles and industrial machinery after heat treatment such as quenching and tempering, etc., and in particular, it relates to steel having high strength and high strength after being subjected to the heat treatment. High toughness heat-treated steel. Background technique [0002] Historically, the strength and toughness of structural materials used in transportation machinery such as automobiles and industrial machinery have been formed into a predetermined shape by extruding heat treatment steel obtained from a steelmaking plant, and then quenched and returned. This is ensured by heat treatment such as fire. Especially when high strength and high toughness are required, it is proposed to control the grain size of old austenite (γ) below 5 μm. [0003] For example, Patent Document 1 describes a high-strength...
Claims
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IPC IPC(8): C22C38/00C22C38/60C21D8/02
CPCC22C38/04C22C38/06C22C38/26C22C38/34C21D8/0226C21D6/005C22C38/28C21D8/0263Y02P10/20C22C38/001C22C38/002C22C38/005C22C38/14C22C38/60
Inventor 畑野等高知琢哉
Owner KOBE STEEL LTD