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Monotonic and Cyclic Creep of Cast Materials for Exhaust Manifolds

SAE International Journal of Materials and Manufacturing

Kungliga Tekniska Hogskolan, Sweden-Christian Öberg
Royal Institute of Technology, Sweden-Stefan Jonsson
  • Journal Article
  • 05-12-02-0012
Published 2019-06-13 by SAE International in United States
Cast materials are creep tested between 600 and 900°C using three methods: (i) tensile testing at different strain rates, (ii) stress relaxation during thermal cycling and (iii) traditional creep tests at constant load. Comparisons are made between fast and slow methods and between monotonic and cyclic deformation modes. The tested materials, SiMo51, SiMo1000, Ni-resist D5S and HK30, are used for exhaust manifolds in heavy-duty diesel engines. The fast and cheap methods, (i) and (ii), were used on all materials, while the tedious and costly method, (iii), was used on SiMo51 only. The creep rates from monotonic tensile tests and stress relaxations during thermal cycling agree well. There is no difference between monotonic and cyclic creep rates, and cyclic rates are practically unchanged with the number of thermal cycles. No or small differences in creep rates are observed when comparing tension and compression, although three of the materials include large graphite nodules. At 700°C, a Norton plot for SiMo51 shows coinciding results for tensile test and compressive stress relaxations, whereas the minimum creep rates from constant…
 
new

Joining Gun Bonds Metal and Plastic in Seconds

  • Magazine Article
  • TBMG-34612
Published 2019-06-01 by Tech Briefs Media Group in United States

The connection of plastics and metals poses a challenge due to the different physical properties of the two materials. All conventional joining options, such as bonds using adhesives or rivets, have their disadvantages — adhesives need time to harden, which delays further processing, and plastics can be easily damaged during riveting. Furthermore, both adhesive bonding and riveting require additional materials that increase production costs.

 
new

Heat Treatment of Steel Raw Materials

AMS E Carbon and Low Alloy Steels Committee
  • Aerospace Material Specification
  • AMSH6875B
  • Current
Published 2019-05-29 by SAE International in United States
This specification covers the requirements for heat-treatment of four classes of steel (See 1.2) and the requirements for furnace equipment, test procedures and information for heat-treating procedures, heat-treating temperatures and material (See 6.3) test procedures. This specification is applicable only to the heat treatment of raw material (See 6.3.1); it does not cover the requirements for the heat treatment of steel parts (See 3.4 and 6.3.2). This specification also describes procedures that, when followed, will produce the desired properties and material qualities within the limitations of the respective alloys tabulated in Tables 1A, 1B, 1C and 1D. Alloys other than those specifically covered herein may be heat treated using all applicable requirements of this specification.
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Steel, Corrosion-Resistant, Investment Castings, 13Cr, Free Machining; Hardened and Tempered

AMS F Corrosion Heat Resistant Alloys Committee
  • Aerospace Material Specification
  • AMS5349F
  • Current
Published 2019-05-10 by SAE International in United States

This specification covers a corrosion-resistant steel in the form of investment castings.

 

Heat Treatment of Wrought Copper Beryllium Alloy Parts

AMS D Nonferrous Alloys Committee
  • Aerospace Material Specification
  • AMS2728C
  • Current
Published 2019-04-30 by SAE International in United States
This specification establishes the requirements for heat treatment of wrought copper beryllium parts (See 1.2.2 and 8.2.1) by users or by their vendors or subcontractors.
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Heat Treatment of Steel Parts General Requirements

AMS E Carbon and Low Alloy Steels Committee
  • Aerospace Material Specification
  • AMS2759G
  • Current
Published 2019-04-23 by SAE International in United States
This specification establishes general requirements for the processes listed in 3.8.1 for heat treatment of steel parts (see 8.2.1) by users or their vendors or subcontractors.
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Numerical Modelling of Metal Forming by SPH with Multi-GPU Acceleration

ESS Engineering Software Steyr-Md Rushdie Ibne Islam, Chong Peng, Alireza Eslamian
Published 2019-04-02 by SAE International in United States
Large material distortion, plastic deformation and forging make the numerical modelling of metal forming a difficult task. Grid-based methods such as the Finite Element Method (FEM) are incapable of simulating this process as these schemes suffer from mesh distortion and mesh entanglement. The mesh-based numerical frameworks with discontinuous enrichment can model finite deformation problems with limited success. Moreover, the presence of flaws, multiple crack surfaces and their interaction make the simulation even more numerically and computationally intensive. In this regard, Lagrangian particle-based meshfree methods are more relevant. There exist several mesh-free methods and among these Smoothed Particle Hydrodynamics (SPH) is a truly meshfree method. In SPH the computational domain is discretised by a set of particles. A given particle interacts only with its neighbouring particles through a kernel function with a constant radius. The interaction between particles stops when the particles move out of each other’s influence domain. Due to the absence of mesh/grids, SPH is naturally equipped to handle large deformation problems. Based on SPH, a solver with multi GPU acceleration for modelling metal…
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Strain Rate Effect on Martensitic Transformation in a TRIP Steel Containing Carbide-Free Bainite

Clemson University-Rakan Alturk
General Motors LLC-Charles Enloe, Vesna Savic, Whitney Poling, Louis Hector
Published 2019-04-02 by SAE International in United States
Adiabatic heating during plastic straining can slow the diffusionless shear transformation of austenite to martensite in steels that exhibit transformation induced plasticity (TRIP). However, the extent to which the transformation is affected over a strain rate range of relevance to automotive stamping and vehicle impact events is unclear for most third-generation advanced high strength TRIP steels. In this study, an 1180MPa minimum tensile strength TRIP steel with carbide-free bainite is evaluated by measuring the variation of retained austenite volume fraction (RAVF) in fractured tensile specimens with position and strain. This requires a combination of servo-hydraulic load frame instrumented with high speed stereo digital image correlation for measurement of strains and ex-situ synchrotron x-ray diffraction for determination of RAVF in fractured tensile specimens. Specifically, the potentially competing effects of strain rate on austenite transformation to martensite were investigated to determine which predominate at nominal strain rates of 0.5 s-1, 5 s-1, 50 s-1 and 500 s-1. A corresponding decrease in austenite volume fraction at a fixed true strain with strain rate suggests that austenite transformation to…
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Multi-Material Topology Optimization for Crashworthiness Using Hybrid Cellular Automata

General Motors-Chandan Mozumder, Simon Xu
Indiana University; Purdue University-Prasad Tapkir, Andres Tovar
Published 2019-04-02 by SAE International in United States
Structures with multiple materials have now become one of the perceived necessities for automotive industry to address vehicle design requirements such as light-weight, safety, and cost. The objective of this study is to develop a design methodology for multi-material structures accountable for vehicle crash durability. The heuristic topology synthesis approach of Hybrid Cellular Automaton (HCA) framework is implemented to generate multi-material structures with the constraint on the volume fraction of the final design. The HCA framework is integrated with ordered-SIMP (solid isotropic material with penalization) interpolation, artificial material library, as well as statistical analysis of material distribution data to ensure a smooth transition between multiple practical materials during the topology synthesis. Since the proposed method does not rely on additional variables to represent material selection, the computational cost of this method is independent of the number of the phases in a multi-material design. The dynamic simulations of a sphere ball impacting an armor plate and the frontal crash on a car bumper are used to evaluate the proposed multi-material topology synthesis algorithm. The practical materials…
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Development of Strength Distributed Hot Stamp Parts

Toyota Motor Corporation-Shunsuke Miyagawa, Masatomo Niihara, Tomoaki Ihara
Published 2019-04-02 by SAE International in United States
1Structural parts, such as the center pillar, are a multi-layer structure. They are a combination of high-strength panels and high-toughness panels, to control the deformation mode during a crash. If we can make this multi-layered structure as one panel, consisting of different hardness within it, we will be able to make a lightweight part. In this study, we have developed a method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole panel is hardened by quenching within the hot stamp process. Next, certain areas of the panel are softened by partial tempering. We have found that the temperature zone for softening is between A1 and A3, and it is easy to perform a rapid and accurate tempering by utilizing induction heating around the Curie temperature between A1 and A3 transformation temperature.As a result, we have established the method to fabricate the ‘lightweight center pillar’, that has a higher collision resistant performance, by integrating the high-strength part and the high-toughness part into a single panel.
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