Reinforcing Bar Composition for High Strength and Seismic Ductility
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Solution Overview
Problem
Existing reinforcing bars do not meet the demand for ultra-high strength and seismic performance while maintaining cost-effectiveness and productivity, as they require excessive alloying elements that increase production costs.
Innovation Solution
A reinforcing bar composition with controlled amounts of carbon, silicon, manganese, chromium, vanadium, copper, molybdenum, aluminum, nickel, tin, phosphorus, sulfur, and nitrogen, along with a microstructure of tempered martensite, ferrite, pearlite, and bainite, achieved through a manufacturing process involving reheating, hot-rolling, and controlled cooling to form a hardened core layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excessive alloying elements are added to increase plastic deformation capacity and seismic performance, then the seismic performance is improved, but the production cost increases
Solution Approach 1:
The invention changes the chemical composition parameters by precisely controlling the content ranges of multiple alloying elements (C: 0.10-0.45%, Si: 0.50-1.00%, Mn: 0.40-1.80%, Cr: 0.10-1.00%, V: 0.00-0.20%, Cu: 0.00-0.40%, Mo: 0.00-0.50%, Ni: 0.00-0.25%, Al: 0.015-0.070%). This parameter optimization achieves the required plastic deformation capacity and seismic performance while avoiding excessive alloying that would increase production cost.
2Strength
If reinforcing bar strength is increased to meet future demands of 1.0 GPa or greater, then the strength is improved, but the complexity of achieving both strength and ductility increases
Solution Approach 1:
The invention creates a composite microstructure consisting of multiple phases (ferrite, pearlite, bainite, and martensite) within the steel matrix. This composite microstructure enables the reinforcing bar to achieve ultra-high yield strength (≥1.0 GPa) while maintaining adequate ductility and seismic performance, avoiding the need for overly complex processing procedures.
3Ease of operation
If plastic deformation capacity is increased through alloying elements, then the seismic performance is improved, but the production cost increases
Solution Approach 1:
The invention optimizes the content parameters of multiple alloying elements to achieve the required plastic deformation capacity. By controlling C at 0.10-0.45%, Si at 0.50-1.00%, Mn at 0.40-1.80%, and other elements within specified ranges, the steel achieves adequate elongation and plastic deformation capacity for seismic performance without excessive alloying that would increase production cost.
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 solution provides a reinforcing bar with yield strength of 700 MPa or greater, a TS/YS ratio of 1.25 or greater, and excellent seismic performance, while reducing alloying element usage and simplifying processes, thereby delaying structural collapse during earthquakes and reducing construction costs.
Implementation Method 1
the surface layer portion includes tempered martensite, and the central portion is composed of a microstructure including ferrite, pearlite and bainite
Implementation Method 2
manufacturing a rolled material by hot-rolling the reheated semi-finished product
Implementation Method 3
reheating a semi-finished product
Implementation Method 4
cooling the rolled material to the Ms temperature or below
Data Source
AI summary
Provided is an ultra-high-strength reinforcing bar and a method for manufacturing the same are disclosed. In an exemplary embodiment, the ultra-high-strength reinforcing bar includes an amount of 0.10 to 0.45 wt % carbon (C), an amount of 0.5 to 1.0 wt % silicon (Si), an amount of 0.40 to 1.80 wt % manganese (Mn), an amount of 0.10 to 1.0 wt % chromium (Cr), an amount greater than 0 and less than or equal to 0.2 wt % vanadium (V), an amount greater than 0 and less than or equal to 0.4 wt % copper (Cu), an amount greater than 0 and less than or equal to 0.5 wt % molybdenum (Mo), an amount of 0.015 to 0.070 wt % aluminum (Al), an amount greater than 0 and less than or equal to 0.25 wt % nickel (Ni), an amount greater than 0 and less than or equal to 0.1 wt % tin (Sn), an amount greater than 0 and less than or equal to 0.05 wt % phosphorus (P), an amount greater than 0 and less than or equal to 0.03 wt % sulfur (S), an amount of 0.005 to 0.02 wt % nitrogen (N), and the remainder being iron (Fe) and other inevitable impurities.