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A strengthening and toughening treatment process of high-nickel and low-carbon series steel

A treatment process and strengthening and toughening technology, which is applied in the field of strengthening and toughening treatment of high-nickel and low-carbon series steel, can solve the problem that the toughness of steel materials decreases, affects the safety of ultra-low temperature pressure vessels, and is difficult to significantly improve the high-nickel and low-carbon series steel. Low temperature toughness and other issues, to achieve the effect of reducing manufacturing costs

Inactive Publication Date: 2019-02-22
XIJING UNIV
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Problems solved by technology

When it is lower than room temperature, as the temperature decreases, the toughness of the steel material will drop sharply, and may even burst into brittle fracture, causing serious consequences.
Nickel-based low-temperature steel solves this problem to a certain extent. The main features of this series of steel are low carbon content, high nickel content, high purity, high strength, high low-temperature impact toughness, good welding performance, and the lowest service temperature. It can reach -196°C, so it has become the main material for manufacturing low-temperature pressure vessels, such as liquid ethylene (-104°C), liquefied natural gas (-163°C), liquid oxygen (-183°C), liquid nitrogen (-196°C) storage tanks , with the development of the petrochemical industry, the liquefaction, separation, storage, transportation and application of gases are becoming more and more extensive, and higher and higher requirements are put forward for the low-temperature performance and reliability of low-temperature technology and equipment, while traditional heat treatment processes are difficult to significantly improve The low-temperature toughness of high-nickel and low-carbon series steels seriously affects the safety of ultra-low temperature pressure vessels, such as the Chinese patent "a heat treatment process for improving low-temperature impact toughness of 9Ni steel" (application publication number: CN104745770A) The steel contains nickel mass percentage For Ni=8.5~10% and "a kind of heat treatment quenching cryogenic treatment method of low-temperature nickel steel" (application publication number: CN201310291288.8) carry out liquid nitrogen cryogenic treatment to 9Ni steel; Therefore, the development of new ultra-low temperature pressure vessel steel Toughening treatment process is very necessary

Method used

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  • A strengthening and toughening treatment process of high-nickel and low-carbon series steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] A process for strengthening and toughening high-nickel low-carbon series steels, the steps of which are:

[0020] Step 1: The material is 6.5Ni high-nickel low-carbon pressure vessel steel heated to 1150°C for 12 hours, then cooled to room temperature to obtain a martensite-based structure;

[0021] Step 2: Quenching in the two-phase region: reheat the martensite-based structure obtained in step 1 to the two-phase region at 670°C, keep it warm for 0.5 hours, and then immediately oil-quench to room temperature to obtain "new martensite + original Martensite" composite structure;

[0022] Step 3: Quenching in the single-phase zone: re-add the composite structure of "new martensite + original martensite" obtained in step 2 to 840°C for single-phase zone quenching, keep it warm for 0.5 hours, and then oil quench to room temperature to obtain the workpiece;

[0023] Step 4: Cryogenic treatment: Cool the workpiece obtained in step 3 to -196°C with liquid nitrogen, keep it wa...

Embodiment 2

[0027] A process for strengthening and toughening high-nickel low-carbon series steels, the steps of which are:

[0028] Step 1: Heating 9.5Ni high-nickel low-carbon pressure vessel steel to 1100°C for 16 hours, then cooling to room temperature to obtain a martensite-based structure;

[0029] Step 2: Quenching in the two-phase region: reheat the martensite-based structure obtained in step 1 to the two-phase region at 700°C, keep it warm for 1 hour, and then immediately oil-quench to room temperature to obtain "new martensite + original Martensite" composite structure;

[0030] Step 3: Quenching in the single-phase zone: re-add the composite structure of "new martensite + original martensite" obtained in step 2 to 850°C for single-phase zone quenching, keep it warm for 0.5 hours, and then oil quench to room temperature to obtain the workpiece;

[0031] Step 4: Cryogenic treatment: Cool the workpiece obtained in Step 3 to -196°C with liquid nitrogen, keep it warm for 1 hour, an...

Embodiment 3

[0035] A process for strengthening and toughening high-nickel low-carbon series steels, the steps of which are:

[0036] Step 1: Heating 9.5Ni high-nickel low-carbon pressure vessel steel to 1050°C for 18 hours, then cooling to room temperature to obtain a martensite-based structure;

[0037] Step 2: Quenching in the two-phase region: reheat the martensite-based structure obtained in step 1 to the two-phase region at 690°C, keep it warm for 40 minutes, and then immediately oil-quench to room temperature to obtain "new martensite + original Martensite" composite structure;

[0038] Step 3: Quenching in the single-phase zone: re-add the composite structure of "new martensite + original martensite" obtained in step 2 to 880°C for single-phase zone quenching, keep it warm for 1 hour, and then oil quench to room temperature to obtain the workpiece;

[0039] Step 4: Cryogenic treatment: Cool the workpiece obtained in step 3 to -196°C with liquid nitrogen, keep it warm for 1.5 hours...

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Abstract

The invention discloses a strengthening and toughening treatment process of high-nickel and low-carbon serial steel. The high-nickel and low-carbon serial steel is firstly heated for insulation, and is cooled to reach the room temperature to obtain a structure mainly using martensite; then, the structure is reheated in a two-phase region for insulation, is quenched in oil to reach the room temperature to obtain a newborn martensite+original martensite composite structure; the composite structure is reheated in a single-phase region for quenching and insulation, and is quenched in oil to reach the room temperature to obtain a workpiece; then, the workpiece is cooled by liquid nitrogen for insulation, and is returned to the room temperature to obtain an uniform and fine lath martensite structure; and finally, the lath martensite structure is tempered for insulation, and is cooled in air to reach the room temperature to obtain a fine lath martensite+reversal austenite+few carbides composite structure. The process has the advantage of improving low-temperature toughness of ultralow-temperature pressure containers and higher strength.

Description

technical field [0001] The invention relates to a steel strengthening and toughening treatment process, in particular to a high-nickel and low-carbon series steel strengthening and toughening treatment process. Background technique [0002] At room temperature, steel materials usually have good strength and toughness and are widely used. When it is lower than room temperature, as the temperature decreases, the toughness of the steel material will drop sharply, and even brittle fracture may occur suddenly, causing serious consequences. Nickel-based low-temperature steel solves this problem to a certain extent. The main features of this series of steel are low carbon content, high nickel content, high purity, high strength, high low-temperature impact toughness, good welding performance, and the lowest service temperature. It can reach -196°C, so it has become the main material for manufacturing low-temperature pressure vessels, such as liquid ethylene (-104°C), liquefied nat...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/18C21D6/04C22C38/08C22C38/12C22C38/04C22C38/02C22C38/40C22C38/44
CPCC21D1/18C21D6/04C21D2211/001C21D2211/008C22C38/02C22C38/04C22C38/08C22C38/12C22C38/40C22C38/44
Inventor 乔勋朱炎张蕴党波孙琳琳
Owner XIJING UNIV
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