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Short-time upper bainite isothermal heat treatment process for industrial 9SiCr steel

A technology of isothermal heat treatment and bainite, applied in heat treatment equipment, heat treatment process control, manufacturing tools, etc., can solve problems such as not being effectively solved

Active Publication Date: 2008-03-12
TIANJIN LIXINSHENG ADVANCED CASTING
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are few reports at home and abroad on the research work on the bainite treatment process on steel
This problem has not yet been effectively resolved

Method used

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  • Short-time upper bainite isothermal heat treatment process for industrial 9SiCr steel

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Embodiment

[0020] Embodiment: The short-time upper bainite isothermal heat treatment process of industrial 9SiCr steel, its process curve is shown in Figure 2, according to the following three steps:

[0021] The first step, austenitizing treatment: the 9SiCr steel is heated to 900 ° C for 30 minutes in a conventional resistance heating furnace under air conditions;

[0022] The second step, cooling treatment after austenitization: cooling the above 9SiCr steel from 900 °C to the upper bainite isothermal temperature range, the cooling rate is 20 °C / s, to avoid slow cooling to cause pearlite inside the material , Proeutectoid ferrite and other structures and rapid cooling generate large thermal stress inside the material;

[0023] The third step, upper bainite isothermal treatment: In a conventional salt bath furnace, the 9SiCr steel is isothermally held at 350°C for 10 minutes to obtain an unconventional upper bainite composed of single-phase ferrite and the metallographic microstructure...

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Abstract

The invention provides a short-time upper bainite isothermal heat treatment process for an industrial 9SiCr steel, which is characterized in that the process comprises three procedures: 1. austenite treating under 900-950 DEG C; 2. cooling at rate 20-40 DEG C per second to 350-380 DEG C; 3. isothermal treating 1-20 minutes under 350-380 DEG C to get unordinary upper bainite textile, after the material is isothermal, cooling by water to room temperature. All above three procedures are carried out in an air atmosphere. The step 1 uses an ordinary resistance furnace, the step 2 and 3 use ordinary salt bath furnace. The advantages with the invention is that 9SiCr steel gets unordinary upper bainite textile comprising single-phase ferrite and of small needle like shape but not feather shape in metallurgical microscopic structure, the material strength and toughness is improved for the upper bainite textile of 9SiCr steel.

Description

【Technical field】 [0001] The invention relates to a bainite heat treatment process for steel, in particular to a short-time upper bainite isothermal heat treatment process for industrial 9SiCr steel. 【Background technique】 [0002] It is traditionally believed that the upper bainite structure in steel consists of two phases of ferrite and carbide, carbides are distributed between ferrite laths, and the metallographic structure presents a feather shape (this invention is called conventional feather structure) . The strength and toughness of this organization are not good, so it is avoided in engineering. It is worth noting that the conventional feather bainite structure is generally formed under the condition of isothermal phase transformation for a long time. [0003] If the phase transformation isothermal time is shortened, the upper bainite may appear in a new form, that is, an unconventional form. The unconventional upper bainite structure changes the phase composition...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/20C21D11/00
Inventor 刘庆锁
Owner TIANJIN LIXINSHENG ADVANCED CASTING