Hot-Rolled Titanium Plate Edge Defect Suppression by Side Remelting

Solution Overview

Problem

Conventional methods for producing hot-rolled titanium plates often result in surface defects at the edge portions due to pores in the ingot not being addressed during the breakdown process, leading to reduced yield and increased scarfing during pickling.

Innovation Solution

A method involving electron beam re-melting or plasma arc melting processes to form a titanium slab with a fine-grained microstructure layer on the side surfaces, followed by a finishing process to ensure slab flatness and surface roughness, and hot rolling with a specific arc length of contact to inhibit pore opening and surface defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a breakdown process is omitted to simplify production, then productivity increases, but surface defects at edge portions occur due to pores not being addressed

Engineering Contradiction:

Improveproduction efficiencyVSAvoidsurface quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by performing electron beam melting or plasma arc melting to create a fine-grained microstructure layer on the side surfaces of the titanium slab before hot rolling. This pre-treatment addresses the pore issues that would otherwise manifest as surface defects during rolling, eliminating the need for a separate breakdown process while maintaining surface quality.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical and chemical parameters of the titanium slab surface through controlled melting and solidification processes. By adjusting melting parameters (electron beam energy, plasma arc power) and controlling the cooling rate, a fine-grained microstructure is created that prevents pore formation and surface defects during subsequent hot rolling.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional melting methods are used with cylindrical molds, then manufacturing simplicity is maintained, but the breakdown process becomes necessary increasing complexity

Engineering Contradiction:

Improvemold simplicityVSAvoidprocess complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention changes the mold geometry parameter from cylindrical to rectangular, enabling direct production of slabs with dimensions suitable for hot rolling. This parameter change allows omission of the breakdown process while maintaining ease of manufacture through the use of simple rectangular molds in electron beam or plasma arc melting processes.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If rectangular column-shaped ingots are cast to eliminate breakdown process, then productivity increases, but pores in the ingot cause surface defects during hot rolling

Engineering Contradiction:

Improveproduction efficiencyVSAvoidsurface defect prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention utilizes phase transitions (melting and solidification) through electron beam melting or plasma arc melting to create a fine-grained microstructure in the side surfaces of the rectangular ingot. This controlled phase transition eliminates pores and creates a reliable surface that will not develop defects during hot rolling, maintaining both high productivity and surface quality.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The invention creates a composite microstructure with a fine-grained layer on the side surfaces and a coarser interior structure. This composite structure provides the dual benefit of eliminating surface defects during rolling while maintaining the productivity advantages of direct rectangular ingot casting without breakdown processing.

Inventive Principle:

Principle #40Composite materials

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 suppresses surface defects at edge portions, reducing the need for scarfing and increasing yield by ensuring good surface properties of the hot-rolled titanium plates.