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A heat treatment method for improving low-temperature toughness of low-chromium stainless steel welded joints

A heat treatment method and technology for welding joints, applied in heat treatment furnaces, heat treatment equipment, furnace types, etc., can solve the problems of lack of mechanical properties and inability to obtain mechanical properties of retained austenite, and achieve operability, repeatable operation, and equipment And the effect of low environmental requirements and strong operability

Active Publication Date: 2021-07-20
WUHAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Retained austenite cannot be obtained by high temperature tempering to improve mechanical properties, and the tempered martensite structure composed of ferrite + carbide does not have high mechanical properties

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] A heat treatment method for improving the low-temperature toughness of low-chromium stainless steel welded joints. The thermal treatment method described in this embodiment is:

[0024] This embodiment adopts 12% Cr type stainless steel 1.4003, the dual-phase structure is ferrite + martensite, adopts molten electrode argon arc welding, and welds a steel plate with a thickness of 6mm, butts horizontally, with a 60° groove, and a welding wire of 1.2mm. E308L austenitic stainless steel solid wire; the shielding gas is 97% Ar+3% CO 2 The mixed gas, two welds are completed. The heat input of each weld is 0.6~0.8kJ / mm. The post-welding processing size is 5×10×55mm 3 V-notch impact specimens with a notch depth of 2 mm.

[0025] The heat treatment process in this embodiment is a single heat treatment process; the heat treatment method is the overall heat treatment: first heat the resistance furnace to 750-850 ° C, then open the furnace door to put the weldment in, close the...

Embodiment 2

[0028] A heat treatment method for improving the low-temperature toughness of low-chromium stainless steel welded joints. The thermal treatment method described in this embodiment is:

[0029] In this example, 12% Cr-type stainless steel 1.4003 is used. The stainless steel is a stainless steel welded pipe with a wall thickness of 5mm manufactured by the plasma welding method, with a diameter of 711mm. There is no groove and no gap, and a small amount of E308L welding wire is filled to obtain a suitable reinforcement. . The small hole plasma welding method is used for single-pass welding, and the welding heat input is about 1.3kJ. The post-welding processing size is 5×10×55mm 3 V-notch impact specimens with a notch depth of 2 mm.

[0030] In the double heat treatment process of the heat treatment process in this embodiment, the temperature of the furnace is raised to 850-1000° C., and then the steel pipe is put into the furnace, kept for 10-30 minutes, taken out of the furna...

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Abstract

The invention relates to a heat treatment method for improving the low-temperature toughness of low-chromium stainless steel welded joints. The technical solution is: use single heat treatment process or double heat treatment process for low chromium stainless steel welded joints, the heat treatment method is overall heat treatment or local heat treatment, the heat treatment temperature is 700-1000 ℃, heat preservation for 5-30 minutes, and then air-cooled or water-cooled . The brittle transition temperature of low-chromium stainless steel welded joints after low-temperature toughness heat treatment is reduced from above 0°C to below -40°C, and the tensile properties, bending properties and corrosion resistance are not reduced. The low-chromium stainless steel welded joint: the chromium content is 11-14wt%, and the dual-phase structure is ferrite+martensite. The invention has short holding time, simple process, low cost, strong operability and low requirements on equipment and working conditions; it can meet the mechanical performance requirements of structures, containers, pipes and machine parts, and is suitable for this type of stainless steel Welded joints obtained by all methods.

Description

technical field [0001] The invention relates to the technical field of low-chromium stainless steel welded joints. Specifically relates to a heat treatment method for improving the low-temperature toughness of low-chromium stainless steel welded joints. Background technique [0002] Low chromium (11-14%) stainless steel is by far the most economical stainless steel because it does not contain nickel or contains a small amount of nickel. There are many varieties of this type of stainless steel, including ferritic stainless steel, martensitic stainless steel and ferritic + martensitic two-phase stainless steel, etc., with different chemical compositions and application fields. Among them, the 12Cr ferrite + martensitic two-phase stainless steel has good comprehensive properties, including corrosion resistance, mechanical properties and processing properties, and the nickel content is less than 1%, which is an ideal alternative to carbon steel. Stainless steel materials in th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/18C21D9/50C21D6/00
CPCC21D1/18C21D6/002C21D9/505C21D2211/005C21D2211/008
Inventor 吴开明张心保
Owner WUHAN UNIV OF SCI & TECH
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