Stainless steel for use under circumstance where organic acid and saline are present

a technology of organic acid and saline, which is applied in the field of stainless steel, can solve the problems of accelerating the corrosion of stainless steel by organic acid, and achieve the effect of improving the corrosion resistance of organic acid and a large amount of common sal

Inactive Publication Date: 2005-01-27
NIPPON YAKIN IND KK
View PDF1 Cites 13 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

(in the formula, Cr, Mo and N show the content of (wt %) each ingredient.) Further, the inventors of the present invention have found that when the amount of CaO and MgO contained in the inclusion of the stainless steel is reduced and the main components of the inclusion in stainless steel is altered to SiO2 or Al2O3, the corrosion resistance in the condi

Problems solved by technology

And they found that in the case of fermentation process which generate organic acid such as amino acid, citric acid or lactic acid, t

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Stainless steel for use under circumstance where organic acid and saline are present
  • Stainless steel for use under circumstance where organic acid and saline are present
  • Stainless steel for use under circumstance where organic acid and saline are present

Examples

Experimental program
Comparison scheme
Effect test

experiment 1

As the first step, the inventors of the present invention investigated the difference between the environment in the manufacturing process of soy sauce which has a fermentation process and organic acid such as amino acid or lactic acid generate during said fermentation process and the environment in which such organic acids are not existing. In the experiments, commercial SUS316L of 2 mm in thickness was used as the specimen and two pieces which were cut to 20 mm×25 mm×2 mm and 60 mm×20 mm×2 mm were piled up and spot resistance welding was done at 4 points, thus the test piece with crevice for corrosion test was prepared. Although the ordinary soy sauce contains various kinds of organic acid, for the purpose to simplify the system, 4 kinds of test solution mentioned below were prepared. Namely, glutamic acid and asparagic acid, which are a kind of amino acid and are the typical organic acid generates at the fermentation process and lactic acid, citric acid and acetic acid which are...

experiment 2

For the purpose to investigate the mechanism of the enhancement of corrosion by organic acid, the inventors of the present invention carried out the surface analysis of the SUS316L test piece which was dipped into high concentrated sodium chloride solution containing organic acid for long time and electrochemical measurement in said solution. Specifically, following 3 kinds of test solution were prepared and maintained at 35° C. 2-{circle over (1)}: 17% sodium chloride 2-{circle over (2)}: 17% sodium chloride+1% glutamic acid 2-{circle over (3)}: 17% sodium chloride+1% lactic acid

SUS316L flat plate test pieces polished with #400 emery grinding paper under wet condition were dipped into the above mentioned test solutions for 1 week, and the structural feature of the surface passive film was analyzed by Auger electron spectroscopic analyzer (hereinafter shortened to AES). And the surfaces of same test pieces were observed by a scanning electron microscope (hereinafter shortened ...

experiment 3

The peculiarity of the environment of soy sauce manufacturing plant containing common salt in high concentration in which organic acid exists, the deterioration of the surface passive film by organic acid and the mechanism to enhance the corrosion by selective dissolution of the inclusions mainly composed of CaO or MgO are recited above. As the next step, the inventors of the present invention carried out the following experiment aiming to find out the proper composition of the stainless steel which exhibits good corrosion resistance in such a particular environment. Stainless steel, whose chemical composition is in the range mentioned below, was produced by an induction furnace so as the weight ratio of CaO+MgO in oxide inclusions in steel to be variously changed, and ingots were obtained.

C: 0.008-0.035 wt %, Si: 0.02-0.24 wt %, Mn: 0.13-0.92 wt %, P: 0.017-0.034 wt %, S: 0.001-0.003 wt %, Ni: 6.44-34.83 wt %, Cr: 16.51-25.12 wt %, Mo: 2.06-7.47 wt %, Cu: 0.01-0.86 wt %, W: 0.01...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

PropertyMeasurementUnit
Fractionaaaaaaaaaa
Fractionaaaaaaaaaa
Fractionaaaaaaaaaa
Login to view more

Abstract

The present invention provides a stainless steel which is suitable for use in the food manufacturing plant, particularly a soy sauce manufacturing plant. A stainless steel to be used in the environment which contains organic acid and common salt comprising, C; 0.05 wt % or less, Si; 1.00 wt % or less, Mn; 1.00 wt % or less, P; 0.040 wt % or less, S; 0.03 wt % or less, Ni; 40.0 wt % or less, 16.0 wt %≦Cr≦26.0 wt %, 2.0 wt %≦Mo≦8.0 wt %, 0.05 wt %≦Al≦0.100 wt %, 0.10 wt %≦N≦0.30 wt %, Mg: 0.005 wt % or less, Ca; 0.0010 wt % or less and balance consisting of Fe and inevitable impurities, and satisfying equation (1),
Cr+3.3Mo+20N≧38   (1)
wherein, Cr, Mo and N show the content of each ingredients by weight %.

Description

FIELD OF THE INVENTION The present invention relates to a stainless steel which is superior in resistance to crevice corrosion and in resistance to stress corrosion cracking, and suited to the food manufacturing plant, preferably to the food manufacturing plant in the process of which organic acid such as amino acid, citric acid or acetic acid are generated and also the contents of common salt is high, in particular to the soy sauce manufacturing plant. DESCRIPTION OF THE PRIOR ART In general, for the food manufacturing plant, stainless steel, steel coated by inorganic or organic layer or FRP are used according to the contained ingredients in the foods to be handled, temperature or the operating conditions, especially, the use of stainless steel is increasing from the view point of the easy maintenance, low maintenance cost and excellent cleaning ability. In general, in the food manufacturing plant, such as soft drink, beer or milk, standard stainless steel, for example, SUS304 or...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): C22C38/00C22C38/06C22C38/44
CPCC22C38/001C22C38/002C22C38/004C22C38/44C22C38/04C22C38/06C22C38/02
Inventor KOBAYASHI, YUTAKATANIUCHI, TOSHIHIKONAKAO, YOSHIKUNI
Owner NIPPON YAKIN IND KK
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap