Unlock instant, AI-driven research and patent intelligence for your innovation.

Ultra-low carbon bake-hardening steel anti-aging performance evaluation method

A technology of bake hardening and evaluation methods, applied in the direction of applying stable tension/compression to test material strength, strength characteristics, instruments, etc., can solve the problem of producing Lüders bands, accelerating natural aging, and being difficult to apply to ultra-low carbon steel and other problems, to achieve the effect of accurate evaluation, good effect, simple and fast operation

Inactive Publication Date: 2019-01-29
TANGSHAN IRON & STEEL GROUP +1
View PDF6 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the material is aged before molding, Lüders bands may be produced during the molding process, affecting the quality of the appearance parts, and in severe cases, the molding requirements cannot be met
However, in industrial production, it is difficult to stamp the steel strip in the car factory immediately after production, which inevitably requires a certain amount of transportation and storage time, which increases the risk of aging of the strip steel; especially in high temperature environments, Accelerates natural aging
The patent application with publication number CN 107014681A provides a method for quickly evaluating the natural aging resistance of low-carbon aluminum-killed steel, which uses the bake hardening value as the criterion, and the sample needs to be pre-stretched before baking; but the method is difficult to apply to ultra-low carbon steel

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1: The timeliness evaluation method of the steel for ultra-low carbon bake hardening adopts the following specific process.

[0016] The main weight components of the steel strip to be evaluated are: C 0.0015%, Mn 0.21%, S 0.0070%, P 0.032%, Als0.045%, Nb 0.012%, N 23ppm, and the rest are Fe and unavoidable impurities. The performance after annealing and finishing is: yield strength R p0.2 =202MPa, tensile strength R m =314MPa, yield point elongation YPE 原 =0. Make a sample with a gauge length of 80mm and a parallel section width of 20mm; place it in an oven and bake for 58 minutes at a temperature of 100°C; take it out and air-cool to room temperature for stretching, YPE 烘烤 =0.12%; evaluate the anti-natural aging time of the steel strip for 2 to 3 months. After follow-up tracking and testing, the anti-natural aging time of the steel belt is 82 days.

Embodiment 2

[0017] Embodiment 2: The timeliness evaluation method of the steel for ultra-low carbon bake hardening adopts the following specific process.

[0018] The main weight components of the steel strip to be evaluated are: C 0.0018%, Mn 0.15%, S 0.0010%, P 0.020%, Als0.035%, Nb 0.008%, N 25ppm, and the rest are Fe and unavoidable impurities. The performance after annealing and finishing is: yield strength R p0.2 =180MPa, tensile strength R m =290MPa, yield point elongation YPE 原 =0. Make a sample with a gauge length of 80mm and a parallel section width of 20mm; place it in an oven and bake for 59 minutes at a temperature of 105°C; take it out and air-cool to room temperature for stretching, YPE 烘烤 =0.24%; evaluate the anti-natural aging time of the steel strip for 1 to 2 months. After follow-up tracking and testing, the anti-natural aging time of the steel belt is 42 days.

Embodiment 3

[0019] Embodiment 3: The timeliness evaluation method of the steel for ultra-low carbon bake hardening adopts the following specific process.

[0020] The main weight components of the steel strip to be evaluated are: C 0.0022%, Mn 0.26%, S 0.0060%, P 0.026%, Als0.038%, Nb 0.009%, N 18ppm, and the rest are Fe and unavoidable impurities. The performance after annealing and finishing is: yield strength R p0.2 =215MPa, tensile strength R m =338MPa, yield point elongation YPE 原 =0. Make a sample with a gauge length of 80mm and a width of 20mm in the parallel section, and the tensile direction of the sample is perpendicular to the rolling direction of the strip steel; place it in the furnace and bake it for 60 minutes at a temperature of 101°C; take it out and air cool it to room temperature, stretched, YPE 烘烤 =0.14%; the anti-natural aging time of the evaluation steel strip is 2 to 3 months. After follow-up tracking and testing, the anti-natural aging time of the steel belt i...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
yield strengthaaaaaaaaaa
tensile strengthaaaaaaaaaa
yield strengthaaaaaaaaaa
Login to View More

Abstract

The invention discloses an ultra-low carbon bake-hardening steel anti-aging performance evaluation method. The ultra-low carbon bake-hardening steel anti-aging performance evaluation method comprisesthe following steps of: (1) preparing a sample from the steel to be evaluated, and the yield point elongation of an original sample when stretched is 0, that is, YPE<original> = 0; (2) baking the sample, cooling to room temperature, performing uniaxial stretching, and recording the yield point elongation YPE<baking> during stretching; and (3) using the yield point elongation YPE to evaluate the natural aging resistance of the steel at the room temperature: if the YPE<baking> is less than or equal to 0.1%, the anti-aging performance is more than 3 months; if the YPE<baking> is greater than 0.1%and less than or equal to 0.2%, the anti-aging performance is 2 to 3 months; if the YPE<baking> is greater than 0.2% and less than or equal to 0.3%, the anti-aging performance is 1 to 2 months; and if the YPE<baking> is greater than 0.3%, the anti-aging performance is less that 1 month. The ultra-low carbon bake-hardening steel anti-aging performance evaluation method evaluates the aging time ofthe ultra-low carbon bake-hardening steel stored at the room temperature using the YPE value through an artificial method in a laboratory; the method is simple and fast to operate; the evaluation is accurate; and the effect is good.

Description

technical field [0001] The invention relates to an alloy property evaluation method, in particular to a method for evaluating the timeliness of ultra-low carbon bake-hardening steel. Background technique [0002] In order to meet the requirements of the anti-denting performance of the outer covering of the car, and the materials used have excellent formability, in the manufacture of these external parts, such as the outer door panels, fenders, etc., ultra-low carbon baking is used in most cases. Steel for bake hardening. This type of steel mainly retains 5-15ppm of free C / N atoms in the matrix, and the strength is improved by baking after forming; but the existence of free interstitial atoms in the matrix makes the material have a high risk of natural aging, that is, at room temperature , as the storage time prolongs, the interstitial atoms will diffuse to the vicinity of the dislocations to form Coriolis air clusters. If the material is aged before molding, Lüders bands m...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
CPCG01N3/08G01N2203/0017
Inventor 李桂兰刘丽萍夏明生刘春雨
Owner TANGSHAN IRON & STEEL GROUP