Ni-Based Superalloy Forging with Cr Oxide Coating
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Solution Overview
Problem
In closed die forging of Ni-base superalloys, glass lubricants often fail to maintain uniform thickness at hot forging temperatures, leading to increased friction, forming load, and temperature unevenness, which affects the quality and reliability of the forged product.
Innovation Solution
A method involving a preliminary oxidation step to generate a Cr oxide coating film on the forging stock, followed by coating with a borosilicate glass lubricant, ensures uniform lubrication and reduced friction during hot forging, maintaining wettability and preventing glass lubricant flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a glass lubricant is applied on a forging stock during hot forging, then the friction between the forging stock and die is reduced, but the glass lubricant partially flies after the temperature increases to hot forging temperature, causing non-uniform coating
Solution Approach 1:
The patent applies a chromium oxide coating to the forging stock surface before applying the glass lubricant. This preliminary oxidation treatment creates a stable base layer that prevents the glass lubricant from flying off during temperature increase, ensuring uniform coating thickness is maintained throughout the hot forging process.
2Temperature
If a glass lubricant is used for thermal insulation and friction reduction, then these functions are achieved, but when the glass lubricant is not uniformly applied, temperature unevenness occurs during forging
Solution Approach 1:
The chromium oxide coating is applied beforehand to prevent glass lubricant flight during heating, ensuring uniform coating thickness that provides consistent thermal insulation and prevents temperature unevenness throughout the forging process.
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
This approach allows for consistent glass lubricant coverage, reducing forming loads and temperature unevenness, enabling the production of high-quality, near-net-shape forged products with improved mechanical properties and reduced press loads.
Implementation Method 1
a preliminary oxidation step of previously generating a Cr oxide coating film having a film thickness of 0.5 to 50 μm on the forging stock
Implementation Method 2
The main effect of a lubricant is the operation of reducing the frictions between a forging stock and a die. This effect is achieved by forming a continuous lubrication coating film on a forging stock while maintaining an optimum viscosity of a lubricant during hot forging
Implementation Method 3
A glass lubricant has the function of thermal insulation, as well as the function of reducing the frictions between a forging stock and a die
Data Source
Figure 1(a)~2(d)
AI summary
There is provided a method of manufacturing an Ni-base superalloy which enables a uniform coat of a glass lubricant to be maintained even after heated to hot forging temperature. The method of manufacturing an Ni-base superalloy in which a forging stock containing an Ni-base superalloy, coated with a lubricant, is subjected to hot forging includes: a preliminary oxidation step of previously generating a Cr oxide coating film having a film thickness of 0.5 to 50 µm on the forging stock thereby to obtain a preliminarily oxidized material; a lubricant coating step of coating the preliminarily oxidized material with a glass lubricant containing borosilicate glass as a main component thereby to obtain a material to be forged; and a hot forging step of hot forging the material to be forged thereby to obtain a hot forged material.