Steel is in a battle to retain market share as automotive engineers face tough decisions about how to reduce weight. Steel producers have introduced advanced steels that are lower weight and higher quality than the mild steels they replace. However, engineers are not happy with the quality control on much of the steel the receive, based on comments made on a recent Design News survey conducted by RBI Research in Waltham, MA. A few examples:
“The material that I have been getting lately is not rolled into a true rectangular profile. One side of the longer edge is often slightly curved, near the shorter edge.” The criticism refers to AISI 1018 cold-rolled steel (low-carbon, manganese-rich).
”Need a better micro structure.” Referring to 8620 steel, a hardenable chromium, molybdenum, nickel low-alloy steel often used for carburizing.
”(I need) better consistency of crystalline structure for low alloy steels.” Referring to low alloy (2.25%Cr - 1.0% Mo) steels
”Need better resistance to corrosion from H2S and organic sulfur and corrosion from naphthenic acids in crudes /bitumens.” Referring to A516 series of carbon steel and TP 316/317 types of 18-8 stainless steel.
”Need better avaialblity of cold-heading quality of 8640 alloy steel in diameters needed to produce 1-inch to 1 ½-inch fasteners.
”Better finish. Less scale.” Hot-rolled steel.
”Better varnish for magnet wire.”
”Get increased surface hardness along with better corosion resistance.” Referring to stainless steel generally.
Admittedly, some of the problems relate to poor quality from Asian suppliers, where definitions of specifications can vary widely, to be generous. One survey respondent said: “There needs to be a clear expectation with regards to rusting/corrosion with type 304 and others as it relates to Cr and Ni content. The ‘junk’ from China is usually at the minimum for Ni.”
But many comments indicated there is a significant problem in consistency from all sources, either in grain structure, or chemical composition or in forming. More than 200 engineers participated in the survey, and they were promised confidentiality. Thanks to our readers who participated. A detailed report of the composite findings will be published in the Design News Trend Watch supplement in August. I’m going to cherry pick more of the specific comments in this blog over the next few weeks. Hopefully, some suppliers are reading, and take notes on potential improvements.
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SpaceX has 3D printed and successfully hot-fired a SuperDraco engine chamber made of Inconel, a high-performance superalloy, using direct metal laser sintering (DMLS). The company's first 3D-printed rocket engine part, a main oxidizer valve body for the Falcon 9 rocket, launched in January and is now qualified on all Falcon 9 flights.
Lawrence Livermore National Laboratory and MIT have 3D-printed a new class of metamaterials that are both exceptionally light and have exceptional strength and stiffness. The new metamaterials maintain a nearly constant stiffness per unit of mass density, over three orders of magnitude.
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