High Cr-Ni Alloy Seamless Pipe Piercing
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Solution Overview
Problem
High Cr-high Ni alloy steel billets exhibit poor deformability and increased deformation resistance during piercing and rolling, leading to grain boundary melting cracking (melted rash) on the inner surface and reduced plug life in seamless steel pipe manufacturing, with existing methods failing to address these issues effectively.
Innovation Solution
A method for manufacturing seamless steel pipes using high Cr-high Ni alloy billets, involving heating under specific conditions and piercing/rolling with an inclined roll type piercing mill, where the roll gouge circumferential speed is set to 2.28 m/sec or higher, and the heating temperature is between 1180°C and 1250°C, to prevent melted rash and improve plug life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high Cr-high Ni alloy steel billet is used for manufacturing seamless steel pipe, then corrosion resistance and strength are improved, but deformation resistance increases and processability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling heating temperature (1150-1250°C) and roll circumferential speed (2.28 m/sec or higher) to optimize the deformation behavior of high Cr-high Ni alloy steel during piercing and rolling, resolving the contradiction between improved corrosion resistance and deteriorated processability
2Reliability
If high Cr-high Ni alloy steel billet is pierced and rolled, then strength and corrosion resistance of the pipe are improved, but deformation resistance increases causing melted rash on inner surface
Solution Approach 1:
The patent changes process parameters by setting heating temperature between 1150-1250°C and roll circumferential speed at 2.28 m/sec or higher, which controls the deformation rate and heat generation during piercing and rolling, preventing grain boundary melting and melted rash formation while maintaining the corrosion resistance benefits of high Cr-high Ni alloy steel
Solution Approach 2:
The patent applies the skipping principle by increasing roll circumferential speed to 2.28 m/sec or higher, which reduces the time duration of deformation and heat generation during piercing and rolling, allowing the process to quickly pass through the critical temperature range before grain boundary melting can occur
3Reliability
If high Cr-high Ni alloy steel billet is processed by piercing and rolling, then superior corrosion resistance is achieved, but plug life is reduced due to increased deformation resistance
Solution Approach 1:
The patent optimizes process parameters by controlling heating temperature (1150-1250°C) and roll circumferential speed (2.28 m/sec or higher) to reduce deformation resistance during piercing and rolling, thereby extending plug life while maintaining the corrosion resistance advantages of high Cr-high Ni alloy steel
4Temperature
If rolling speed is decreased to reduce heat generation, then processing heat is reduced, but plug life deteriorates due to increased deformation resistance and prolonged rolling time
Solution Approach 1:
The patent changes the roll circumferential speed parameter to 2.28 m/sec or higher, which maintains sufficiently short processing time to prevent excessive heat generation and grain boundary melting, while also keeping deformation resistance at acceptable levels to preserve plug life
Solution Approach 2:
The patent applies the skipping principle by setting roll circumferential speed at 2.28 m/sec or higher, which allows the piercing and rolling process to complete quickly before excessive heat generation can occur, thereby preventing melted rash while maintaining acceptable plug life
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents melted rash on the inner surface and prolongs plug life by optimizing the heating temperature and roll speed, ensuring efficient processing and maintaining production efficiency.
Implementation Method 1
heating the billet under conditions satisfying the following formula (1), and then piercing and rolling the billet
Data Source
Figure 1~2
AI summary
a billet made of high Cr-high Ni alloy, which contains, by mass percent, 20 to 30 % of Cr, 30 to 50 % of Ni, and at least one element selected from Mo and W with a value "Mo + 0.5 W" of 1.5 % or more is heated under conditions satisfying the following formula (1), and then the billet is pierced and rolled using an inclined roll type piercing mill with a roll gouge circumferential speed of 2.28 m/sec or higher. This prevents melted rash on the inner surface and lengthens the plug life. T≤1575-4.45×Vf-104.7×-lnth/ro wherein T indicates a heating temperature (°C) of the billet, Vf indicates the roll gouge circumferential speed (m/sec), ro indicates a radius (mm) of a billet at an entry-side, and tn indicates a radial thickness (mm) of a pipe after piercing.