Duplex Stainless Steel Tube Rolling for Target Yield Strength
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Solution Overview
Problem
The existing processes for producing duplex stainless steel tubes are laborious and costly, requiring extensive trials to determine the optimal process parameters for achieving the desired yield strength, which is inefficient and resource-intensive.
Innovation Solution
A process is developed that sets specific Q-value and cold reduction (R) parameters using a formula that considers the composition of the duplex stainless steel and targeted yield strength, allowing for the determination of process parameter values for R and Q, thereby improving manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extensive trials are performed to determine optimal process parameters, then the desired yield strength of duplex stainless steel tubes can be achieved, but the manufacturing process becomes laborious and costly
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships between process parameters (cold reduction R, Q-value) and the resulting yield strength. Instead of trial-and-error, the invention uses formulated equations that directly calculate optimal parameter values based on desired yield strength targets, thereby improving manufacturing precision while enhancing productivity.
Solution Approach 2:
The patent replaces the mechanical trial-and-error system with a computational system. By substituting physical experimentation with mathematical calculations and formulas, the invention eliminates laborious trials while maintaining accurate control over yield strength, thus resolving the contradiction between precision and productivity.
2Manufacturing precision
If extensive trials are performed to determine optimal process parameters, then the desired yield strength of duplex stainless steel tubes can be achieved, but the cost increases
Solution Approach 1:
The patent uses parameter changes by formulating direct mathematical relationships that calculate optimal process parameters (cold reduction R, Q-value) based on desired yield strength. This eliminates costly trial productions while achieving precise yield strength control, thereby reducing manufacturing costs while maintaining high precision.
Solution Approach 2:
The patent applies preliminary action by calculating and determining optimal process parameters before actual production begins. By pre-calculating the required cold reduction and Q-value using the provided formulas, the invention avoids costly trial-and-error during manufacturing, thus reducing energy loss and production costs while ensuring desired yield strength.
3Productivity
If process parameters are set based on specific composition and desired yield strength using formulated calculations, then manufacturing efficiency improves, but the complexity of determining parameter values increases
Solution Approach 1:
The patent replaces complex trial-and-error processes with straightforward mathematical calculations. By substituting iterative experimentation with direct formula-based computations, the invention simplifies the determination of process parameters while significantly improving manufacturing efficiency, thus resolving the contradiction between productivity and complexity.
Data Source
AI summary
The present disclosure relates to a process of producing a duplex stainless steel tube, said process comprising the steps of a) producing an ingot or a continuous casted billet of said duplex stainless steel; b) hot extruding the ingot or the billet obtained from step a) into a tube; and c) cold rolling the tube obtained from step b) to a final dimension thereof; wherein the outer diameter D and the wall thickness t of the cold rolled tube is 50-250 mm respectively is 5-25 mm, wherein, for the cold rolling step, R and Q are set such that the following formula is satisfied: Rp0.2target = 416.53 + 113.26 ⋅ logQ + 4.0479 ⋅ R + 2694.9 ⋅ C% - 82.750 ⋅ (logQ) 2 - 0.04279 ⋅ R 2 - 2.2601 ⋅ logQ ⋅ R + 16.9 ⋅ Cr% + 26.1 ⋅ Mo% + 83.6 ⋅ N% ± Z (1) wherein Rp0.2target is targeted yield strength and is 800-1100 MPa; Q = (W0 - W1)x(OD0-W0)/W0((OD0-W0)-(OD1-W1)) (2) wherein W1 is tube wall thickness before cold rolling, W0 is tube wall thickness after cold rolling, OD1 is outer diameter of tube before cold rolling, and OD0 is outer diameter of tube after cold rolling; R is cold reduction and is defined as (3); wherein A1 is tube cross section area before cold rolling and A0 is tube cross section area after cold rolling; Z=65; and wherein 0<Q<3.6.