Austenitic Heat-Resistant Alloy for Engine Bolts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional heat-resistant alloys, such as SUH660, contain high amounts of expensive nickel, increasing manufacturing costs and limiting the cost-effectiveness of high-temperature applications, while requiring improved tensile strength and hardness at elevated temperatures.
Innovation Solution
Austenitic heat-resistant alloys with optimized compositions, including reduced nickel content and increased titanium, combined with specific precipitation hardening heat-treatment technologies, to enhance tensile strength and hardness without relying on costly nickel, and a manufacturing method involving cold forging, rolling, heat-treating, and surface treating to produce heat-resistant bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high nickel content (26% Ni) is used in SUH660 alloy, then tensile strength at elevated temperatures is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the alloy by reducing nickel content from 26% to 17-22% and adjusting other elements (Cr: 11-16%, Mo: 0.3-1.0%, V: 0.1-0.4%, Ti: 2.7-3.2%, C: 0.01-0.08%). This parameter optimization maintains tensile strength at elevated temperatures while significantly reducing manufacturing cost by eliminating expensive nickel content.
Solution Approach 2:
The patent creates a composite alloy system that combines multiple elements (Cr, Mo, V, Ti, C, Ni) in optimized proportions to achieve the desired mechanical properties at elevated temperatures without relying heavily on nickel. The synergistic combination of these elements provides both strength and cost-effectiveness.
2Ease of manufacture
If nickel content is reduced to lower manufacturing cost, then manufacturing cost decreases, but tensile strength at elevated temperatures may deteriorate
Solution Approach 1:
The patent systematically adjusts multiple composition parameters simultaneously: reducing Ni to 17-22%, increasing Cr to 11-16%, adding Mo (0.3-1.0%), V (0.1-0.4%), and Ti (2.7-3.2%). These coordinated parameter changes ensure that tensile strength at elevated temperatures is maintained even with reduced nickel content, while achieving cost reduction.
Solution Approach 2:
The patent introduces chromium (Cr), molybdenum (Mo), vanadium (V), and titanium (Ti) as intermediary elements that can substitute for nickel in providing high-temperature strength. These elements act as mediators to maintain mechanical properties while reducing dependence on expensive nickel.
3Device complexity
If conventional heat treatment is used, then processing is simple, but hardness and tensile strength at elevated temperatures are insufficient
Solution Approach 1:
The patent applies preliminary cold forging and rolling to the alloy before heat treatment to create a refined microstructure with appropriate grain size and phase distribution. This preliminary mechanical processing prepares the material to respond more effectively to subsequent heat treatment, achieving superior high-temperature properties without overly complex processes.
Solution Approach 2:
The patent optimizes heat treatment parameters (temperature, time, cooling rate) to precipitate strengthening phases and refine the microstructure. By carefully controlling these thermal parameters, the alloy achieves enhanced hardness and tensile strength at elevated temperatures while maintaining process simplicity.
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 achieves improved tensile strength and hardness by up to 10% compared to conventional alloys, reducing manufacturing costs and maintaining high-temperature performance, while avoiding the expense of nickel.
Implementation Method 1
optimizing a rolling pressure, a precipitation hardening heat-treatment technology
Data Source
AI summary
Disclosed are a heat-resistant alloy used in a heat-resistant bolt and the like for fastening high temperature parts of an engine in a vehicle and the like, and a method of manufacturing a heat-resistant bolt using the heat-resistant alloy. Particularly, the austenitic heat-resistant alloy includes, based on a total weight of the heat-resistant alloy, carbon (C) in an amount of about 0.01 to about 0.08 wt %, silicon (Si) in an amount of about 0.01 to about 1.00 wt %, manganese (Mn) in an amount of about 0.01 to about 2.00 wt %, nickel (Ni) in an amount of about 17 to about 22 wt %, titanium (Ti) in an amount of about 2.7 to about 3.2 wt %, chromium (Cr) in an amount of about 11 to 16 wt %, molybdenum (Mo) in an amount of about 0.3 to about 1.0 wt %, vanadium (V) in an amount of about 0.1 to about 0.4 wt %, and a remainder of iron (Fe) and optionally an inevitable impurity.