Uncoated High-Speed Steel Cold Rolling Roll Design
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Solution Overview
Problem
Current forged rolls used in the cold rolling industry face challenges in achieving low residual internal stresses, wear resistance, and surface texture retention without chrome plating, which is becoming environmentally unacceptable, and there is a need for rolls that can operate safely and efficiently without coatings while maintaining high performance and longer lifespan.
Innovation Solution
A forged roll with a specific steel composition (0.8-1% C, 0.2-0.5% Mn, 0.2-2% Si, 7-13% Cr, 0.6-1.6% Mo, >1-3% V) and microstructure (tempered martensite with <5% retained austenite and an open eutectic carbide network) that exhibits hardness between 780-840 HV and internal compressive stresses of -300 to -500 MPa, produced using a process involving induction heating and tempering, to achieve improved crack resistance and tribological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If chrome plating is applied to forged rolls to improve wear resistance and surface texture retention, then the roll lifespan is extended (2 to 8 times longer), but environmental restrictions make this practice increasingly unacceptable
Solution Approach 1:
The invention extracts and eliminates the chrome plating coating from the roll system, replacing it with an uncoated HSS roll design that achieves comparable performance through material composition and heat treatment alone, thereby removing the environmental harm associated with chrome plating
Solution Approach 2:
The invention changes the material parameters by using high speed steel with specific alloy compositions (0.6-1.6% Mo, 1.0-3.0% V, 7.0-13.0% Cr) and applies controlled heat treatment parameters (tempering at 450-530°C for 3 times) to achieve the desired hardness and stress properties without coating
2Object-affected harmful factors
If rolls are designed to operate without chrome plating to eliminate environmental harm, then environmental safety is improved, but achieving equivalent wear resistance and surface texture retention becomes difficult
Solution Approach 1:
The invention uses composite material properties by combining high speed steel with specific alloying elements (Mo, V, Cr, Mn, Si) in precise proportions to create a material that inherently provides both wear resistance and surface texture retention without requiring external coating
Solution Approach 2:
The invention achieves the required reliability by precisely controlling material composition parameters and heat treatment parameters (tempering temperature and duration) to produce an uncoated roll with hardness 780-840 HV and internal compressive stresses -300 to -500 MPa
3Object-affected harmful factors
If rolls are made with high speed steel to eliminate coating and reduce environmental harm, then environmental performance is improved, but the rolls may have high residual internal stresses leading to cracks or explosion
Solution Approach 1:
The invention resolves the stress issue by changing the heat treatment parameters, specifically applying tempering at 450-530°C for 3 times, which transforms the internal stress state from tensile to compressive (-300 to -500 MPa), thereby improving crack resistance and operational safety
Solution Approach 2:
The invention converts the potentially harmful high residual internal stresses into beneficial compressive internal stresses through controlled tempering, which actually improves the roll's resistance to cracking and explosion while maintaining the environmental benefits of being uncoated
4Reliability
If rolls are designed for higher hardness to improve wear resistance, then surface texture retention is improved, but the rolls become more brittle and prone to cracking
Solution Approach 1:
The invention optimizes the balance between hardness and crack resistance by precisely controlling the tempering parameters (450-530°C for 3 times), which achieves hardness 780-840 HV while simultaneously creating internal compressive stresses that enhance crack resistance
Solution Approach 2:
The invention uses composite material properties with specific alloying elements (particularly 0.6-1.6% Mo and 1.0-3.0% V) combined with heat treatment to create a microstructure that provides both high hardness for wear resistance and sufficient toughness to prevent cracking
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 roll with enhanced wear resistance, reduced crack propagation, and improved safety, maintaining surface texture and performance equivalent to coated rolls, while avoiding environmental concerns and extending roll lifespan.
Implementation Method 1
Hardening the roll by induction heating
Implementation Method 2
Tempering the roll
Data Source
AI summary
A forged roll for use, inter alia, in the cold rolling industry and a method of producing a forged roll as described. The roll has a steel composition, by weight, with 0.8 to less than 1% C, 0.2 to 0.5% Mn, 0.2 to 2.0% Si, 7.0 to 13.0% Cr, 0.6 to 1.6% Mo, more than 1.0 to 3.0% V, the remainder being Fe and impurities. The steel is tempered martensite with retained austenite at less than 5% per volume with eutectic carbides of less than 5% by volume, a hardness between 780-840 HV, and internal compressive stresses of between −300 to −500 MPa.