Search Results for quality descriptors

This article addresses classifications and designations for carbon and low-alloy steel sheet and strip product forms based on composition, quality descriptors, mechanical properties, and other factors. Carbon steel sheet and strip are available as hot-rolled and as cold-rolled products. Low-alloy steel sheet and strip are used primarily for applications that require the mechanical properties normally obtained by heat treatment. The descriptors of quality used for hot-rolled plain carbon steel sheet and strip and cold-rolled plain carbon steel sheet include structural quality, commercial quality, drawing quality, and drawing quality, special killed. The surface texture of low-carbon cold-rolled steel sheet and strip can be varied between rather wide limits. The modified low-carbon steel grades discussed in the article are designed to provide sheet and strip products having increased strength, formability, and/or corrosion resistance. The article also summarizes the key operations involved in the three alternative direct casting processes: thin slab, thin strip, and spray casting.

Wire rod is a semifinished product rolled from billet on a rod mill and is used primarily for the manufacture of wire. Steel wire rod is usually cold drawn into wire suitable for further drawing; for cold rolling, cold heading, cold upsetting, cold extrusion, or cold forging; or for hot forging. The article explains these operations, along with the several recognized quality and commodity classifications applicable to steel wire rods. The heat treatments commonly applied to steel wire rod, either before or during processing into wire, include annealing, spheroidize annealing, patenting, and controlled cooling. When the end product must be heat treated, the heat treatment and mechanical properties should be clearly defined. Carbon steel rods are produced in various grades or compositions: low-carbon, medium-low-carbon, medium-high-carbon, and high-carbon steel wire rods. Rod for the manufacture of carbon steel wire is produced with manufacturing controls and inspection procedures intended to ensure the degree of soundness and freedom from injurious surface imperfections necessary for specific applications. This article also describes the various quality descriptors applicable to the rods as well as standard qualities and commodities available in alloy steel wire rod.

Cold-finished steel bars are carbon and alloy steel bar products (round, square, hexagonal, flat, or special shapes) that are produced by cold finishing previous hot-wrought bars. by means of cold drawing, cold forming, turning, grinding, or polishing (singly or in combination) to yield straight lengths or coils that are uniform throughout their length. Cold-finished bars fall into five classifications: cold-drawn bars; turned and polished bars; cold-drawn, ground, and polished bars; turned, ground, and polished bars; cold-drawn, turned, ground, and polished bars. Different size tolerances are applicable to cold-finished products, depending on shape, carbon content, and heat treatment. When used to identify cold-finished steel bars, the various quality descriptors are indicative of many characteristics, such as degree of internal soundness, relative uniformity of chemical composition, and relative freedom from detrimental surface imperfections. Cold drawing significantly increases machinability, tensile and yield strengths of steel bars. Two special die-drawing processes have been developed to give improved properties over those offered by standard drawing practices. These processes are cold drawing using heavier-than-normal drafts, followed by stress relieving; and drawing at elevated temperatures.

This article addresses classifications and designations for carbon steels and low-alloy steels, particularly high-strength low-alloy (HSLA) steels, based on chemical composition, manufacturing methods, finishing method, product form, deoxidation practice, microstructure, required strength level, heat treatment and quality descriptors. It describes the effects of alloying elements on the properties and characteristics of steels. The article provides extensive tabular data pertaining to domestic and international designations of steels.

This article provides an overview of the different classification and designation systems of wrought carbon steel and alloy steel product forms with total alloying element contents not exceeding 5″. It lists the quality descriptors, chemical compositions, cast or heat composition ranges, and product analysis tolerances of carbon and alloy steels. The major designation systems discussed include the Society of Automotive Engineers (SAE)-American Iron and Steel Institute (AISI) designations, Unified Numbering System (UNS) designations, American Society for Testing and Materials (ASTM) designations, Aerospace Material Specification (AMS), and other international designations and specifications.

Low-carbon steel sheet and strip are used primarily in consumer goods. This article discusses quality descriptors and mechanical properties of low-carbon steel sheet and strip and carbon and low-alloy steel plate. Alloy steel sheet and strip are used primarily for those special applications that require the mechanical properties normally obtained by heat treatment. Steel sheet is coated in coil form before fabrication either by the steel mills or by specialists called coil coaters. Porcelain enamels are glass coatings applied primarily to products or parts made of sheet steel, cast iron, or aluminum to improve appearance and to protect the metal surface.

Hot-rolled steel bars and other hot rolled steel shapes are produced from ingots, blooms, or billets converted from ingots, or from strand cast blooms and billets, and comprise a variety of sizes and cross sections. This article provides a brief discussion on mechanical properties, quality descriptors and chemical compositions of hot-rolled steel bars, cold-finished steel bars, steel wire rod and steel wire. It contains tables that provide size tolerances for cold-finished carbon steel bar and cold-finished alloy steel bar.

Hot-rolled steel bars and other hot-rolled steel shapes are produced from ingots, blooms, or billets converted from ingots or from strand cast blooms or billets and comprise a variety of sizes and cross sections. Most carbon steel and alloy steel hot-rolled bars and shapes contain surface imperfections with varying degrees of severity. Seams, laps, and slivers are probably the most common defects in hot-rolled bars and shapes. Another condition that could be considered a surface defect is decarburization. Hot-rolled steel bars and shapes can be produced to chemical composition ranges or limits, mechanical property requirements, or both. Hot-rolled carbon steel bars are produced to two primary quality levels: merchant quality and special quality. Merchant quality is the least restrictive descriptor for hot-rolled carbon steel bars. Special quality bars are employed when end use, method of fabrication, or subsequent processing treatment requires characteristics not available in merchant quality bars.

The production and use of steel plate is aided by a system of standard designations and associated specifications defining composition, property, and performance ranges. This article contains an extensive amount of information on the designations and grades of plate products and how they are made. Although most steel plate is used in the hot-finished condition, some applications require one or more heat treating steps to mitigate imperfections and/or improve relevant qualities. The article discusses these interconnected factors as well as their impact on mechanical properties and critical fabrication issues, including formability, machinability, and weldability.

Machine vision, also referred to as computer vision or intelligent vision, is a means of simulating the image recognition and analysis capabilities of the human eye and brain system with digital techniques. The machine vision functionality is extremely useful in inspection, supervision, and quality control applications. This article presents a variety of machine vision functions for different purposes and provides a comparison of machine and human vision capabilities in a table. It discusses the processes of a machine vision system: image acquisition, image preprocessing, image analysis, and image interpretation. The article provides information on the uses of machine vision systems in three categories of manufacturing applications: visual inspection, identification of parts, and guidance and control applications.

This article briefly introduces the concepts of failure analysis and root cause analysis (RCA), and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. It reviews four fundamental categories of physical root causes, namely, design deficiencies, material defects, manufacturing/installation defects, and service life anomalies, with examples. The article describes several common charting methods that may be useful in performing an RCA. It also discusses other failure analysis tools, including review of all sources of input and information, people interviews, laboratory investigations, stress analysis, and fracture mechanics analysis. The article concludes with information on the categories of failure and failure prevention.

Process optimization is the discipline of adjusting a process to optimize a specified set of parameters without violating engineering constraints. This article reviews data-driven optimization methods based on genetic algorithms and stochastic models and demonstrates their use in powder-bed fusion and directed energy deposition processes. In the latter case, closed-loop feedback is used to control melt pool temperature and cooling rate in order to achieve desired microstructure.

This article provides an overview of the general methods of metal powder production. It details the primary methods for particle sizing used in additive manufacturing: sieving, laser diffraction and scattering, and digital image analysis. Methods of interpreting and understanding particle size distribution (PSD) data are presented, with an emphasis on the differences between count- and volume-based PSDs. The article then outlines practices for both qualitative and quantitative assessment of particle morphology.

This article briefly introduces the concepts of failure analysis, including root-cause analysis (RCA), and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. It initially provides definitions of failure on several different levels, followed by a discussion on the role of failure analysis and the appreciation of quality assurance and user expectations. Systematic analysis of equipment failures reveals physical root causes that fall into one of four fundamental categories: design, manufacturing/installation, service, and material, which are discussed in the following sections along with examples. The tools available for failure analysis are then covered. Further, the article describes the categories of mode of failure: distortion or undesired deformation, fracture, corrosion, and wear. It provides information on the processes involved in RCA and the charting methods that may be useful in RCA and ends with a description of various factors associated with failure prevention.

In materials selection, a decision matrix method refers to any formalized procedure by which materials are ranked prior to a selection decision. This article describes the advantages and limitations of decision matrix methods, as well as the steps involved, with examples. The methods include the Pugh method, the Dominic method, and the Pahl and Beitz method. The article discusses the three important concepts in decision making: alternatives (candidate materials), criteria (objectives), and weighting factors.

Powder-bed additive manufacturing (AM) processes are some of the most commonly used techniques, necessitating the accurate measurement of powder flowability properties. This article discusses some powder flow tests that occur in powder-bed AM machines. These include the Hall/Carney flow test, bulk/tap density, rheometer, and the revolving or rotating drum technique. The three categories of powder properties that are available from rheometer experiments are discussed: bulk, dynamic flow, and shear properties. The article also describes the basic principles and applications of micro-X-ray computed tomography in studying powder porosity characteristics nondestructively.

This article details findability, accessibility, interoperability, and reusability (FAIR) additive manufacturing data management principles and examines related motivations, benefits, and challenges. It explains opportunities to advance the state of the AM community efforts in fostering FAIR data management practices/principles and outlines the consequence of such efforts on technology maturation and industrialization for AM technologies.

This article reviews the essential parts of the complex process of quantitative image analysis to assist automatic image analysis in laboratories. It describes the basic difference between the bias of classical manual stereological analysis and quantitative image analysis. The article concentrates on the basic properties of digital measurements that are the core of quantitative image analysis. It provides a brief description of the specimen and apparatus preparation as well as the image acquisition. The article explains how to evaluate stereological parameters and provides the general rules and guidelines for optimization of image processing algorithms from the viewpoint of shape quantification. It concludes with examples that demonstrate the usefulness of automatic image analysis in comparison to manual methods.

This article describes the process of materials selection in relation to the design process, such as materials selection for a new design and materials substitution for an existing design. It reviews the performance characteristics of materials using prototype tests or field tests to determine their performance under actual service conditions. The article describes the selection of a material in relation to the manufacturing process and presents the factors that influence materials selection based on costs and related aspects. These factors include metallurgical requirements, dimensions, processing, quantity, packing, marking, and loading. The article discusses how the needs for materials data evolve as a design proceeds from conceptual to detail design. It describes the methods of materials selection, namely, cost per unit property method, weighted property index method, and limits on properties method.

Acoustical holography is the extension of holography into the ultrasonic domain. The basic systems for acoustical holography are the liquid-surface type and the scanning type. This article discusses the applications for acoustical holography, including inspection of large composite parts, through-transmission breast imaging system, inspection of welds in thick materials, and inspection of sleeve-bearing stock. It describes the basic system for liquid-surface acoustical holography and scanning acoustical holography. A comparison between these techniques is also provided.