Medium-Manganese Steel Forming With Warm Preheating

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Solution Overview

Problem

Current methods for producing medium manganese flat steel products with TRIP/TWIP effects face limitations in deformation degrees and require high deformation forces, which can lead to material failure and reduced elongation capabilities.

Innovation Solution

A method involving pre-heating the flat steel product to temperatures between 60°C and 450°C before deformation, allowing for increased deformation without hardening and reducing deformation forces, thereby enhancing the TRIP/TWIP effects and achieving higher tensile strengths and elongations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If deformation is performed at room temperature on medium manganese flat steel product, then the steel achieves high strength through TRIP effect, but the deformation degree is limited and high deformation forces are required

Engineering Contradiction:
Improvetensile strengthVSAvoiddeformation capability
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies parameter changes by heating the steel to the austenite region (above Ac3 temperature) before deformation. This temperature parameter change transforms the microstructure to austenite, which has superior deformability compared to martensite. After deformation, controlled cooling transforms the austenite to martensite, achieving both high strength and high deformation capability.

Inventive Principle:
Principle #35Parameter changes

2Shape

If deformation forces are increased to achieve higher deformation degrees, then the component shape can be more complex, but material failure risk increases and elongation capabilities are reduced

Engineering Contradiction:
Improvecomponent geometryVSAvoidmaterial failure resistance
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The patent utilizes phase transitions by heating the steel into the austenite region before deformation. The austenite phase has high ductility and can accommodate large deformation degrees without failure. After deformation, the phase transitions to martensite during cooling, providing the desired complex shape while maintaining material reliability and preventing failure.

Inventive Principle:
Principle #36Phase transitions

3Strength

If the steel is deformed in the martensitic region, then high strength is achieved, but the elongation at fracture and deformability are considerably reduced

Engineering Contradiction:
Improvetensile strengthVSAvoidelongation at fracture
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by heating the steel to the austenite region before deformation occurs. This preliminary heating action creates the favorable austenite microstructure that enables high elongation and deformability. The martensitic transformation occurs after deformation during cooling, ensuring both high strength and high elongation are achieved in sequence.

Inventive Principle:
Principle #10Preliminary action

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 increases the maximum deformation capability and residual deformation capacity of the steel components, achieving tensile strengths of 800 MPa to 2000 MPa with elongations greater than 3% while reducing deformation forces and maintaining or improving strength properties.

Implementation Method 1

deforming the flat steel product to form a component by means of a first deforming step at a temperature of the flat steel product of 60° C. to below Ac3

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 2

TRIP steels which have a predominantly ferritic basic microstructure having incorporated residual austenite which can convert into martensite during deformation (TRIP effect)

Methodology Applied
Scientific EffectTRIP effect: Phase Change

Implementation Method 3

a medium manganese flat steel product having 4 to 12 wt. % Mn, preferably more than 5 to less than 10 wt. % Mn and having a TRIP/TWIP effect

Methodology Applied
Scientific EffectTWIP effect: Phase Change

Data Source

PatentUS11214846B2Method for producing a shaped component from a medium-manganese flat steel product and such a component
Publication Date: 2022.01.04 SALZGITTER FLASHSTAHL GMBH

AI summary

The invention relates to a method for producing a component from a medium-manganese flat steel product with 4 to 12 wt % Mn, preferably more than 5 to less than 10 wt % Mn, and with TRIP/TWIP effect. In order to improve the degrees of deformation of the shaped component while at the same time reducing the forming forces, the invention proposes shaping the flat steel product into a component in a first shaping step at a temperature of the flat steel product of 60° C. to below Ac3, preferably from 60° C. to 450° C. The invention also relates to a component produced according to said method and to a use for said components.