Method for qualitatively detecting capillary cracks and segregation of steel used for piston pins

A qualitative detection and piston pin technology, applied in measuring devices, analyzing materials, testing metals, etc., can solve the problem of inability to qualitatively detect steel for piston pins, and achieve the effect of improving brand effect, accurate detection, and improving detection efficiency.

Inactive Publication Date: 2019-01-29
HANDAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this detection method cannot carry out accurate and standardized qualitative detection of steel for piston pins.

Method used

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  • Method for qualitatively detecting capillary cracks and segregation of steel used for piston pins
  • Method for qualitatively detecting capillary cracks and segregation of steel used for piston pins
  • Method for qualitatively detecting capillary cracks and segregation of steel used for piston pins

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Embodiment 1: The method for qualitatively detecting hairlines and segregation of steel for piston pins is as follows.

[0029] (1) A 40Cr round steel sample is used for the piston pin, and the specification of the piston pin is φ58mm in outer diameter and φ27mm in inner diameter. According to the specification of piston pin, the specification of round steel is φ60mm. Such as Figure 4 As shown, the conventional cross-section detection method is used on the left side of the figure, and only point-like segregation can be seen in the interface, which cannot truly reflect the internal segregation of the round steel. Such as Figure 4 As shown, on the right side of the figure, the conventional longitudinal section detection method is used. Only linear segregation along the central longitudinal section can be seen in the interface, which is greatly improved compared with the cross section, but it still cannot fully reflect the internal segregation of the round steel.

[0...

Embodiment 2

[0032] Embodiment 2: The method for qualitatively detecting hairlines and segregation of steel for piston pins is as follows.

[0033]20Cr round steel for piston pins of a piston pin factory, the specifications of the piston pins are φ50mm in outer diameter and φ23mm in inner diameter. According to the specification of piston pin, the specification of round steel is φ52mm. 20Cr is low-carbon steel. According to this inspection method, the processing size: the processing radius of the first step is a=25mm, and the length is R=26mm; the processing radius of the second step is b=17.70mm, and the length is R=26mm; the third step The processing radius is c=10.35mm and the length is 2R=52mm. Detect the outer circle, middle circle and inner circle of the piston pin respectively. Such as Figure 7 , Figure 8 , Figure 9 As shown, no hairlines and black lines were found on the first and second steps, and short clusters of black lines were found on the third step (inner circle are...

Embodiment 3

[0034] Embodiment 3: The method for qualitative detection of hairlines and segregation of steel for piston pins is as follows.

[0035] 20CrH round steel sample is used for the piston pin, and the specifications of the piston pin are φ48mm in outer diameter and φ24mm in inner diameter. According to the specification of piston pin, the specification of round steel is φ50mm. Through process optimization, appropriate secondary cooling water distribution of continuous casting machine, stable process control, reduce center segregation, and improve steel quality. 20CrH is low-carbon steel. According to this inspection method, the processing size: the first step processing radius is a=24mm, the length is R=25mm; the second step processing radius is b=18mm, the length is R=25mm; the third step processing The radius is c=12mm and the length is 2R=50mm. Pickling to detect the condition of each step. Such as Figure 10 shown. No hairlines and segregation lines were found on the firs...

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Abstract

The invention discloses a method for qualitatively detecting capillary cracks and segregation of steel used for piston pins. The method comprises the following steps: processing a round steel sample to form a circular tower shape with three steps, wherein the sizes of formed stepped cylinders are that (1) in the first step, a processing radius is a and a length is R, (2) in the second step, a processing radius is b and a length is R, (3) in the third step, a processing radius is c and a length is 2R, a is the outer radius of the cylinder of a piston pin, c is equal to the radius of the inner bore of the piston pin multiplied by 90-100%, R is the radius of the round steel, and b is equal to 1 / 2(a+c); and subjecting the processed sample to surface acid etching, and then observing and examining the number, length and distribution of capillary cracks on the whole surface of each step. According to the invention, the outer working surface, the inner quality and the inner bore quality of thepiston pin are comprehensively reflected in a point-line-surface manner. The method of the invention improves detection efficiency, reduces detection cost, has the practical cost significance, and lays a foundation for the formulation of inspection standards of steel used for the piston pins.

Description

technical field [0001] The invention relates to a metal detection method, in particular to a qualitative detection method for hairlines and segregation of steel for piston pins. Background technique [0002] The piston pin is a cylindrical pin mounted on the piston skirt of the internal combustion engine. Its middle part passes through the small head hole of the connecting rod to connect the piston and the connecting rod, and transmit the gas force borne by the piston to the connecting rod. Due to the lightweight requirements of automobiles, in order to reduce weight, piston pins are generally made of high-quality alloy structural steel, and the structure is generally a thick-walled hollow cylinder. Piston pins need to withstand high temperature periodic impact loads during work, requiring high enough mechanical strength, wear resistance and fatigue strength, and have high requirements for the quality and cleanliness of the round steel subsurface. The steel used for piston ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N33/204G01N33/2045
CPCG01N33/20
Inventor 李仕超李金波范全保李昂黄晶
Owner HANDAN IRON & STEEL GROUP
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