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Carburizing and quenching process for cold extrusion steel

A carburizing and quenching, steel technology, applied in the direction of metal material coating process, coating, solid diffusion coating, etc., can solve the problems of high cost and complicated process, and achieve the effect of low cost, simple process and elimination of adverse effects

Inactive Publication Date: 2006-01-18
WANXIANGQIANCHAO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention solves the problems of complex process and high cost in the secondary re-quenching heat treatment process in the prior art, and provides a relatively simple process and low cost, which can be obtained after carburizing and direct quenching of cold-extruded steel. The metallographic structure is finer than grade 5 (grain size), the impact toughness, fracture toughness and plasticity of the treated steel are higher, and the tensile strength and static torsional strength are better. The carburizing and quenching process of cold-extruded steel

Method used

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  • Carburizing and quenching process for cold extrusion steel
  • Carburizing and quenching process for cold extrusion steel
  • Carburizing and quenching process for cold extrusion steel

Examples

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Effect test

Embodiment 1

[0016] Example 1: Put the workpiece made of cold-extruded steel into a gas carburizing furnace with a temperature of 950°C in the furnace, heat the workpiece to 950°C at a heating rate of 40°C / min, and the strong carburizing potential is 0.95C%. After 5 hours of heat preservation in the furnace, the carbon potential drops to 0.8C%. After 5 hours of heat preservation in the furnace, the temperature is lowered to 850°C at a rate of 45°C / hour and then quenched with engine oil to obtain finer than grade 5 ( grain size) metallographic structure (such as Figure 6 and Figure 7 shown).

Embodiment 2

[0017] Example 2: Put the workpiece made of cold-extruded steel into a gas carburizing furnace with a temperature of 970°C in the furnace, heat the workpiece to 940°C at a heating rate of 30°C / min, and the strong carburizing potential is 1.05C%. After 3 hours of heat preservation in the furnace, the carbon potential drops to 0.75C%, and then after 2 hours of heat preservation in the furnace, the temperature is lowered to 820°C at a rate of 30°C / hour, and then quenched with engine oil to obtain finer than grade 5 (crystalline grain size) metallographic structure (such as Figure 6 and Figure 7 shown).

Embodiment 3

[0018] Example 3: Put the workpiece made of cold-extruded steel into a gas carburizing furnace with a temperature of 990°C in the furnace, heat the workpiece to 930°C at a heating rate of 50°C / min, and the strong carburizing potential is 1.1C%. After 10 hours of heat preservation in the furnace, the carbon potential drops to 0.8C%. After 8 hours of heat preservation in the furnace, the temperature is lowered to 880°C at a rate of 60°C / hour, and then quenched with engine oil, and the finer than grade 5 (crystalline grain size) metallographic structure (such as Figure 6 and Figure 7 shown).

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Abstract

The present invention is one kind of carbonizing and quenching heat treatment process for cold extruded steel. The present invention features the technological conditions including feeding temperature of 950-990 deg.c; pre-heating rate of 30-50 deg.c / min; heating and maintaining temperature of 920-980 deg.c; forced carbonizing maintaining time of 3-11 hr; diffusion maintaining time of 2-9 hr; temperature lowering rate of 30-60 deg.c / hr; quenching temperature of 820-880 deg.c; forced carbonizing carbon potential of 0.95-1.2 C%; and diffusion carbon potential of 0.7-0.9 C%. The technological process is simple and low in cost, and can obtain metallographic structure finer than grade-5. The treated steel possesses raised impact toughness, breaking toughness, plasticity, tensile strength, torque strength, etc.

Description

technical field [0001] The invention relates to a heat treatment of steel, in particular to a carburizing and quenching heat treatment process of cold extruded steel. Background technique [0002] The existence of coarse-grained steel (metallographic structure coarser than grade 4 (grain size)) will generally have an adverse effect on the mechanical properties, reducing the impact toughness, fracture toughness and plasticity of the steel, and may also reduce the material's Tensile strength, static torsional strength, etc. At present, it is believed that: after the steel is cold-extruded, as long as the deformation of the steel reaches the critical deformation, when the heating temperature is higher than the deformation and recrystallization temperature of the steel (generally around 600°C), no matter what measures are taken, the grains will grow abnormally; Moreover, the higher the heating temperature, the coarser the crystal grains. At present, some traditional heat treat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D1/74C23C8/26
Inventor 王晓华
Owner WANXIANGQIANCHAO CO LTD