I believe this is a pretty old sci-fi short story. As I recall, it takes place on a planet of iron and iron oxide (rust). The only inhabitants are robots. IIRC, a ship lands, or crash lands there, and the astronauts/ space travelers come to an untimely demise. That’s all I can remember.
Your description is not rich in detail, but it reminds me of "Lost Memory", a 1952 short story by Peter Phillips. It matches your description in that a spaceship crash-lands on a planet inhabited only by robots, and it ends very badly for the astronaut although he survived the landing. What doesn't match it that there is only one astronaut, and we are not told that the planet is made of iron or rust.
The story is narrated by a native robot. The astronaut is trapped inside his wrecked spaceship; he is talking to the robots by radio, but the robots believe they are talking to his ship, which they think is an intelligent (but brain-damaged) robot like themselves, as they have no concept of biological life. The story is narrated by one of the robots:
Chirik looked around at us in bewilderment, but he replied courteously, giving the stranger a description of our world.
"Of course," said the stranger. "Of course. Sterile rock and metal suitable only for you. But there must be some way . . ."
He was silent for a while.
"Do you know what growth means?" he asked finally. "Do you have anything that grows?"
"Certainly," Chirik said helpfully. "If we should suspend a crystal of some substance in a saturated solution of the same element or compound—"
"No, no," the stranger interrupted. "Have you nothing that grows of itself, that fruktiffies and gives increase without your intervention?"
"How could such a thing be?"
"Criseallmytee I should have guessed. If you had one blade of gras, just one tiny blade of growing gras, you could extrapolate from that to me. Green things, things that feed on the rich brest of erth, cells that divide and multiply, a cool grove of treez in a hot summer [. . .]"
The following passage indicates that there is probably not a lot of rust present:
Fiff-fiff was still relaying, but no amount of power boost would make the stranger's voice any clearer. It was quite faint now, and there are places on my recorder tape from which I cannot make even the roughest phonetic transliteration.
". . . strength going. Can't get into my zoot . . . done for if they bust through lock, done for if they don't . . . must tell them I need oxygen . . ."
"He's in bad shape, desirous of extinction," I remarked to Chur-chur, who was adjusting his arc-cutter. "He wants to poison himself with oxidation now."
I shuddered at the thought of that vile, corrosive gas he had mentioned, which causes that almost unmentionable condition we all fear—rust.
For more about the story "Lost Memory" see my answer to the old question Robots on planet with no humans until a rocket with a human lands, or you can read the whole story at the Internet Archive.
This could be "Epilogue" (1962), by Poul Anderson. A problem with their ship's spacedrive transports a crew of humans to a planet with a completely mechanical ecosystem, which includes its own native intelligent life. Human lives are lost, and as the human survivors leave the planet, they deduce that it is Earth of the far future. The crew realize that they are the only survivors of our species, reasoning that humans would never have permitted Earth to be so transformed.
You can read "Epilogue" online in The Many Worlds of Poul Anderson (1974), available from the Internet Archive.
There is a scene in H. Beam Piper's "The Cosmic Computer" (originally published in 1963 as "Junkyard Planet") where the main characters land on a planet of iron and iron oxide.
It was used as a ship building yard during a war, and had lots of heavy industry. It was abandoned after the war ended.
Some twenty or thirty years later, the heroes need some things (ships, but also goods) that were manufactured on that planet.
While investigating one of the robot operated factories (one that produced nuclear power units,) they accidentally start up some of the robots. The robots mistake the heroes for junk, and attempt to "clean up" the factory. This leads to the heroes having to destroy at least one robot before they can get one of the supervisor robots online and back in control.
Since none of the good guys gets killed by the robots, this might not be the story you are looking for.
It is, though, the first story that sprang to mind when you mentioned a planet of iron oxide and robots.
Besides, it's a good book if you can find a copy to read.